Engineersdaily | Free engineering database

Use of Lightweight Concrete and Drying Times

<div style="text-align: justify;">Another typical phone call. An owner wants to know how long it will take for the lightweight concrete in the elevated slabs of his new building to dry before he can place the floor covering. The slabs were placed 4 months ago, but tests still show a moisture-vapor-emission rate of 8 pounds per 1000 square feet in 24 hours. The floor-covering manufacturer requires the concrete to be at 3 lbs/1000 sf/24 hrs. Delaying floorcovering installation will delay building occupancy. The owner has never had this problem in other buildings he has constructed. Why won’t this concrete dry? <a href="https://www.engineersdaily.com/2014/03/book-concrete-technology-2nd-edition-am.neville-jj.brooks.html" target="_blank">Concrete</a> is concrete, right?</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">Well, unfortunately it’s not. Many owners and contractors have told us they’ve experienced project delays while waiting for lightweight concrete to dry. Though we couldn’t find any data regarding the drying time of lightweight concrete, field experience tells us that lightweight concrete takes longer to dry than normal-weight concrete. To help fill this information gap, <a href="https://www.engineersdaily.com/2014/07/what-is-flexure-in-reinforced-concrete-members.html" target="_blank">CONCRETE CONSTRUCTION</a> devised a testing program to find out how long it takes lightweight concrete to dry.</div><div><br /></div><h3 style="text-align: left;"><span style="color: #990000;">The test program </span></h3><div><br /></div><div style="text-align: justify;">Three normal-weight concretes with water-cement ratios of 0.31, 0.37, and 0.40 were delivered to a testing lab in 1-cubic-yard loads. A lightweight concrete mix with a water cement ratio of 0.40 was also delivered to the testing lab. The proprietary mixes were supplied by the ready-mix division of CAMAS Colorado, Denver. The normal-weight concrete moisture-vapor-emission test results were reported in THE CONCRETE PRODUCER (Ref. 1). Here we compare the lightweight concrete moisture-vapor-emission test results with those for normal-weight concrete having the same water-cement ratio. The producer tightly controlled water content and water-cement ratio by closely monitoring <a href="https://www.engineersdaily.com/2016/07/overview-aggregates-for-concrete.html" target="_blank">aggregate</a> moisture and water left in the drum. The fresh and hardened properties of the lightweight concrete were as follows:</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">■ 3-inch slump</div><div style="text-align: justify;">■ 4.5% air content</div><div style="text-align: justify;">■ 124-pound-per-cubic-foot unit weight</div><div style="text-align: justify;">■ 48° F temperature</div><div style="text-align: justify;">■ 6850-psi 28-day compressive strength</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">Workers placed and vibrated the concrete in 3-foot-square test slabs 2, 4, 6, and 8 inches thick. After striking off the surface with a 2x4 and floating it by hand, they covered the slabs with plastic sheeting for 3 days. Calciumchloride moisture-emission testing began after the sheeting was removed.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">Moisture-emission tests were conducted in accordance with the test manufacturer’s instructions. Technicians ran one test on each slab at the 3-day age but thereafter ran two tests on each test slab and reported an average test value. </div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">The calcium-chloride test kits were left in place for 72 hours on slabs stored inside the test lab at a 70±3° F and a relative humidity of 28±5%. This is the normal indoor environment during the winter in the Rocky Mountain region, where the tests were conducted, and represents the environment found in many buildings without relative-humidity controls. </div><div style="text-align: justify;"><br /></div><h3 style="text-align: justify;"><span style="color: #990000;">Drying in months instead of weeks </span></h3><div style="text-align: justify;"><br /></div><div style="text-align: justify;"><div class="separator" style="clear: both; text-align: center;"><a href="https://1.bp.blogspot.com/-JtA-Bh9N0h8/X4xXT-UMILI/AAAAAAAAHoY/7eY4YQPtsFQeOUfgXjO-CPhOaF-TFpm-QCNcBGAsYHQ/s862/lightweight-concrete-moisture-vapour-emmission-rates%255Bengineersdaily.com%255D.PNG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="moisture-vapor emission rates for the test slabs after drying for up to 183 days." border="0" data-original-height="808" data-original-width="862" height="375" src="https://1.bp.blogspot.com/-JtA-Bh9N0h8/X4xXT-UMILI/AAAAAAAAHoY/7eY4YQPtsFQeOUfgXjO-CPhOaF-TFpm-QCNcBGAsYHQ/w400-h375/lightweight-concrete-moisture-vapour-emmission-rates%255Bengineersdaily.com%255D.PNG" title="moisture-vapor emission rates for the test slabs after drying for up to 183 days." width="400" /></a></div>The table shows moisture-vapor emission rates for the test slabs after drying for up to 183 days. Drying times are measured from the end of the 3-day curing period to the end of the 72-hour moisture-emission test. Thus the 3-day measurement was taken 6 days after <a href="https://www.engineersdaily.com/2011/05/placing-of-concrete.html" target="_blank">concrete placement</a>. The test data support the following conclusions.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">Lightweight concrete dries slower. Regardless of the test slab thickness, the lightweight concrete took about 6 months to dry to a moisture-vapor emission rate of 3 lbs/1000 sf/24 hrs. Normal-weight concrete of the same water-cement ratio took only 6 weeks of drying in laboratory air to reach the same level (Ref. 1). From previous work (Ref. 2), we know that laboratory drying represents the fastest drying time. So field conditions that include wet-dry cycles will increase the actual time for the slab to reach the specified moisture-vapor-emission limits. </div><div style="text-align: justify;"><br /></div><h3 style="text-align: justify;"><span style="color: #990000;">Thickness effects</span></h3><div style="text-align: justify;"><br /></div><div style="text-align: justify;">As with normal-weight concrete, the moisture-vapor-emission rates were unaffected by slab thickness. </div><div style="text-align: justify;"><br /></div><h3 style="text-align: justify;"><span style="color: #990000;">Don’t blame the contractor</span></h3><div style="text-align: justify;"><br /></div><div style="text-align: justify;">Lightweight concrete offers many advantages. However, any owner using lightweight concrete that’s to be covered by a moisture-sensitive floor covering or any architect/engineer specifying this combination should consider the slower drying time as an important part of the <a href="https://www.engineersdaily.com/2014/03/book-construction-management-and-design-industrial-steel-concrete-el.reedy.html" target="_blank">construction</a> schedule. Once lightweight concrete is specified, the contractor can’t change its drying characteristics. If owners want the benefits of lightweight <a href="https://www.engineersdaily.com/2014/03/ready-mixed-concrete.html" target="_blank">concrete</a> and a fast-track schedule, they may need to consider applying a polymer coating or sheet product to reduce moisture emissions.</div><div><div style="text-align: justify;"><br /></div><h3 style="text-align: justify;"><span style="color: #990000;">References</span></h3><div style="text-align: justify;"><br /></div><div style="text-align: justify;">1. Bruce A. Suprenant and Ward R.
Malisch, “Quick-Dry Concrete: A New
Market for Ready-Mix Producers,”
THE CONCRETE PRODUCER, May 1998.</div><div style="text-align: justify;">2. Bruce A. Suprenant and Ward R.
Malisch, “Are Your Slabs Dry Enough
for Floor Coverings?” CONCRETE CONSTRUCTION, August 1998.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">By Bruce A. Suprenant and Ward Malisch</div></div>

Use of Lightweight Concrete and Drying Times

Another typical phone call. An owner wants to know how long it will take for the lightweight concrete in the elevated slabs of his new build...

Floor and roof systems in reinforced concrete structures

<h2 style="text-align: left;"><span style="color: #cc0000;">Overview</span></h2><div><span style="color: #cc0000;"><br /></span></div><div style="text-align: justify;">Reinforced <a href="https://www.engineersdaily.com/2014/03/book-concrete-technology-2nd-edition-am.neville-jj.brooks.html" target="_blank">concrete</a> structural systems can be formed into virtually any geometry to meet any requirement. Regardless of the geometry, standardized ﬂoor and roof systems are available that provide cost-effective solutions in typical situations. The most common types are classiﬁed as one-way systems and two-way systems. Examined later are the structural members that make up these types of systems.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">It is common for one type of ﬂoor or roof system to be speciﬁed on one entire level of building; this is primarily done for cost savings. However, there may be cases that warrant a change in framing system. The feasibility of using more than one type of ﬂoor or roof system at any given level needs to be investigated carefully.</div><div style="text-align: justify;"><br /></div><h2 style="text-align: left;"><span style="color: #cc0000;">One-Way Systems</span></h2><div><span style="color: #cc0000;"><br /></span></div><div style="text-align: justify;">A <a href="https://www.engineersdaily.com/2016/04/design-of-one-way-slabs.html" target="_blank">one-way reinforced concrete ﬂoor or roof system</a> consists of members that have the main ﬂexural reinforcement running in one direction. In other words, reactions from <a href="https://www.engineersdaily.com/2014/05/how-loads-flow-through-building.html">supported loads</a> are transferred primarily in one direction. Because they are primarily subjected to the effects from bending (and the accompanying shear), members in one-way systems are commonly referred to as <a href="https://www.engineersdaily.com/2014/07/what-is-flexure-in-reinforced-concrete-members.html" target="_blank">ﬂexural</a> members.</div><div style="text-align: justify;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-Dn8t9TdZEIE/X4ICpOlR5QI/AAAAAAAAHnE/qsjTQ6wvNMEcjO7z0ckl3AlPRqnm6yw9QCNcBGAsYHQ/s840/one-way-slab-system%255Bengineeersdaily.com%255D.png" style="margin-left: auto; margin-right: auto;"><img alt="FIGURE 1 One-way slab system." border="0" data-original-height="493" data-original-width="840" height="235" src="https://1.bp.blogspot.com/-Dn8t9TdZEIE/X4ICpOlR5QI/AAAAAAAAHnE/qsjTQ6wvNMEcjO7z0ckl3AlPRqnm6yw9QCNcBGAsYHQ/w400-h235/one-way-slab-system%255Bengineeersdaily.com%255D.png" title="FIGURE 1 One-way slab system." width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><b>FIGURE 1</b> One-way slab system.</td></tr></tbody></table><br />Members in a one-way system are usually horizontal but can be provided at a slope if needed. Sloped members are commonly used at the roof level to accommodate drainage requirements.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">Illustrated in <b>Fig. 1</b> is a one-way slab system. The load that is supported by the slabs is transferred to the beams that span perpendicular to the slabs. The beams, in turn, transfer the loads to the girders, and the girders transfer the loads to the columns.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">Individual spread footings may carry the column loads to the soil below. It is evident that load transfer between the members of this system occurs in one direction.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-AbUj8IDKQUY/X4IFjp2zAMI/AAAAAAAAHnQ/emVOolgPs9cwN8wIBiDbAaUJBO1EPqe7gCNcBGAsYHQ/s825/standard_one_way_joist_system%255Bengineersdaily.com%255D.png" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="FIGURE 2 Standard one-way joist system." border="0" data-original-height="577" data-original-width="825" height="280" src="https://1.bp.blogspot.com/-AbUj8IDKQUY/X4IFjp2zAMI/AAAAAAAAHnQ/emVOolgPs9cwN8wIBiDbAaUJBO1EPqe7gCNcBGAsYHQ/w400-h280/standard_one_way_joist_system%255Bengineersdaily.com%255D.png" title="FIGURE 2 Standard one-way joist system." width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><b style="text-align: right;">FIGURE 2 </b><span style="text-align: right;">Standard one-way joist system.</span></td></tr></tbody></table>Main ﬂexural reinforcement for the one-way slabs is placed in the direction parallel to load transfer, which is the short direction. Similarly, the main ﬂexural reinforcement for the beams and girders is placed parallel to the length of these members. <a href="https://www.engineersdaily.com/2014/04/steps-in-construction-of-reinforced-concrete-structures.html" target="_blank">Concrete</a> for the slabs, beams, and girders is cast at the same time after the forms have been set and the reinforcement has been placed in the formwork. This concrete is also integrated with columns. In addition, reinforcing bars are extended into adjoining members. Like all cast-in-place systems, this clearly illustrates the monolithic nature of reinforced concrete structural members.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">A standard one-way joist system is depicted in <b>Fig. 2.</b> The one-way slab transfers the load to the joists, which transfer the loads to the column-line beams (or, girders). This system utilizes standard forms where the clear spacing between the ribs is 30 in. or less. Because of its relatively heavy weight and associated costs, this system is not used as often as it was in the past.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-UYnP-N2rtZc/X4IGLKngv_I/AAAAAAAAHnY/w1IZY70oQoIkYdiVsPhUwHYzAZvG9fXhQCNcBGAsYHQ/s826/wide-module-joist-system%255Bengineeersdaily.com%255D.png" style="margin-left: auto; margin-right: auto;"><img alt="FIGURE 3 Wide module joist system." border="0" data-original-height="616" data-original-width="826" height="299" src="https://1.bp.blogspot.com/-UYnP-N2rtZc/X4IGLKngv_I/AAAAAAAAHnY/w1IZY70oQoIkYdiVsPhUwHYzAZvG9fXhQCNcBGAsYHQ/w400-h299/wide-module-joist-system%255Bengineeersdaily.com%255D.png" title="FIGURE 3 Wide module joist system." width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><b style="text-align: right;">FIGURE 3 </b><span style="text-align: right;">Wide module joist system.</span></td></tr></tbody></table>Similar to the standard one-way joist system is the wide-module joist system shown in <b>Fig. 3</b>. The clear spacing of the ribs is typically 53 or 66 in., which, according to the Code, technically makes these members beams instead of joists. Load transfer follows the same path as that of the standard joist system.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;"><a href="https://www.engineersdaily.com/2014/06/methods-of-concrete-construction.html" target="_blank">Reinforced concrete</a> stairs are needed as a means of egress in buildings regardless of the number of elevators that are provided. Many different types of stairs are available, and the type of stair utilized generally depends on architectural requirements. Stair systems are typically designed as one-way systems.</div><h2 style="text-align: left;"><span style="color: #cc0000;"><br /></span></h2><h2 style="text-align: left;"><span style="color: #cc0000;">Two-Way Systems</span></h2><div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">As the name suggests, two-way ﬂoor and roof systems transfer the supported loads in two directions. Flexural reinforcement must be provided in both directions.</div><div style="text-align: justify;"><br /></div></div><div style="text-align: justify;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-SesBTlipkC8/X4IGqGgih8I/AAAAAAAAHnk/tqT13v0sEkYwWAv5hzPQqe4ksyUW8-oUwCNcBGAsYHQ/s820/Two-way-beam-supported-slab-system%255Bengineeersdaily.com%255D.png" style="margin-left: auto; margin-right: auto;"><img alt="FIGURE 4 Two-way beam supported slab system." border="0" data-original-height="584" data-original-width="820" height="285" src="https://1.bp.blogspot.com/-SesBTlipkC8/X4IGqGgih8I/AAAAAAAAHnk/tqT13v0sEkYwWAv5hzPQqe4ksyUW8-oUwCNcBGAsYHQ/w400-h285/Two-way-beam-supported-slab-system%255Bengineeersdaily.com%255D.png" title="FIGURE 4 Two-way beam supported slab system." width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><b style="text-align: right;">FIGURE 4 </b>Two-way beam supported slab system.</td><td class="tr-caption"><br /></td><td class="tr-caption" style="text-align: right;"></td><td class="tr-caption" style="text-align: right;"></td></tr></tbody></table>A two-way <a href="https://www.engineersdaily.com/2014/01/Spreadsheet-Analysis-Design-Rectangular-Concrete-Beam-Section-ACI-318-05.html" target="_blank">beam</a> supported slab system is illustrated in <b>Fig. 4</b>. The slab transfers the load in two orthogonal directions to the column-line beams, which, in turn, transfer the loads to the columns. Like a standard one-way joist system, this system is not utilized as often as it once was because of cost.</div><div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">A ﬂat plate system is shown in <b>Fig. 5</b>. This popular system, which is frequently used in residential buildings, consists of a slab supported by columns. The formwork that is required is the simplest of all ﬂoor and roof systems. Because the underside of the slab is ﬂat, it is commonly used as the ceiling of the space below; this results in signiﬁcant cost savings.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-PH_Q7zJeQ9s/X4IHSf2-GrI/AAAAAAAAHns/Zaaf8fF3xXoQ451RyoO16owe9nOnKi7TQCNcBGAsYHQ/s811/flat-plate-system%255Bengineeersdaily.com%255D.png" style="margin-left: auto; margin-right: auto;"><img alt="FIGURE 5 Flat plate system." border="0" data-original-height="583" data-original-width="811" height="288" src="https://1.bp.blogspot.com/-PH_Q7zJeQ9s/X4IHSf2-GrI/AAAAAAAAHns/Zaaf8fF3xXoQ451RyoO16owe9nOnKi7TQCNcBGAsYHQ/w400-h288/flat-plate-system%255Bengineeersdaily.com%255D.png" title="FIGURE 5 Flat plate system." width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><b style="text-align: right;">FIGURE 5 </b><a href="https://www.engineersdaily.com/2014/03/review-of-reinforced-concrete-flat-plate-design.html" target="_blank">Flat plate system</a>.</td></tr></tbody></table><br />Similar to the <a href="https://www.engineersdaily.com/2014/03/review-of-reinforced-concrete-flat-plate-design.html">ﬂat plate system</a> is the ﬂat slab system (<b>Fig. 6</b>). Drop panels are provided around the columns to increase moment and shear capacity of the slab. They also help to decrease slab deﬂection. Column capitals or brackets are sometimes provided at the top of columns.</div><div style="text-align: justify;"><br /></div><div style="text-align: justify;">The two-way system depicted in <b>Fig. 7 </b>is referred to as a two-way joist system or a wafﬂe slab system. This system consists of rows of <a href="https://www.engineersdaily.com/2014/01/basics-of-reinforced-concrete-structural-design.html" target="_blank">concrete</a> joists at right angles to each other, which are formed by standard metal domes. Solid concrete heads are provided at the columns for shear strength. Such systems provide a viable solution in cases where heavy loads need to be supported on long spans.</div></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-b4FKwN6GX4A/X4II0oLysQI/AAAAAAAAHoA/9DGDu4-DghQooMkZvtng3h0gr5QujrimwCNcBGAsYHQ/s814/flat-slab-system%255Bengineeersdaily.com%255D.png" style="margin-left: auto; margin-right: auto;"><img alt="FIGURE 6 Flat slab system." border="0" data-original-height="585" data-original-width="814" height="230" src="https://1.bp.blogspot.com/-b4FKwN6GX4A/X4II0oLysQI/AAAAAAAAHoA/9DGDu4-DghQooMkZvtng3h0gr5QujrimwCNcBGAsYHQ/w320-h230/flat-slab-system%255Bengineeersdaily.com%255D.png" title="FIGURE 6 Flat slab system." width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><b style="text-align: right;">FIGURE 6 </b>Flat slab system.</td></tr></tbody></table><br /><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right;"><tbody><tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-253xwHr1Qdg/X4IJxe1Z-fI/AAAAAAAAHoM/B8PEI11QCj00kW_f3FnEms4uz1yrY_ZxQCNcBGAsYHQ/s783/Two-way-joist-system%255Bengineeersdaily.com%255D.png" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="FIGURE 7 Two way joist system." border="0" data-original-height="447" data-original-width="783" height="183" src="https://1.bp.blogspot.com/-253xwHr1Qdg/X4IJxe1Z-fI/AAAAAAAAHoM/B8PEI11QCj00kW_f3FnEms4uz1yrY_ZxQCNcBGAsYHQ/w320-h183/Two-way-joist-system%255Bengineeersdaily.com%255D.png" title="FIGURE 7 Two way joist system." width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><b style="text-align: right;">FIGURE 7 </b>Two way joist system.</td></tr></tbody></table><br /><div style="text-align: justify;"><br /></div>

Floor and roof systems in reinforced concrete structures

Overview Reinforced concrete structural systems can be formed into virtually any geometry to meet any requirement. Regardless of the geomet...

Structural Design Objectives and Philosophy - A Historical Overview

<div style="text-align: justify;">
Since the start of the formal approaches and procedures for carrying out the structural design, there have been many developments in the underlying principles and the implicit and explicit design objectives. Starting with putting limits in the allowable (working) stresses in various materials to achieve indirect safety factors, the <a href="http://www.engineersdaily.com/2016/11/uncertainty-in-future-flexible-designs.html" target="_blank">design</a> process slowly evolved within last few decades to more explicit consideration of different load and capacity factors. The recognition of the difference between brittle and ductile failure, and the introduction of capacity-based design approaches, led to the more comprehensive performance design using high level of analysis sophistication, and more explicit linkage between demand and performance. The most recent emphasis is on risk-based design, and a more integrated and holistic approach within the framework of consequence-based engineering. This section discusses a brief account of the progression of these design approaches and their impact on the cost, performance, and the final objective of public safety.</div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-rz8GlWTRPmo/XaNWOCtjEkI/AAAAAAAAHjU/MbRasp-V_2kmweOadDsr1wCK_emXqzJCgCNcBGAsYHQ/s1600/Design_Objectives_Philosophy%2528www.engineersdaily.com%2529.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="Structural Design Objectives and Philosophy - A Historical Overview" border="0" data-original-height="1196" data-original-width="1600" height="298" src="https://1.bp.blogspot.com/-rz8GlWTRPmo/XaNWOCtjEkI/AAAAAAAAHjU/MbRasp-V_2kmweOadDsr1wCK_emXqzJCgCNcBGAsYHQ/s400/Design_Objectives_Philosophy%2528www.engineersdaily.com%2529.jpg" title="Structural Design Objectives and Philosophy - A Historical Overview" width="400" /></a></div>
<div style="text-align: justify;">
<a href="http://www.engineersdaily.com/2014/01/basics-of-reinforced-concrete-structural-design.html" target="_blank">Structural design</a> is the process of proportioning the structure to safely resist the applied forces and load effects in the most resource-effective and friendly manner. The term “friendly” refers to the aspect of design dealing with environmental friendliness, sustainability, ease of <a href="http://www.engineersdaily.com/2014/01/reinforced-concrete-mechanics-design-by.html" target="_blank">construction</a>, and usability that are not explicit part of the strength consideration. Resources refer to the use of material, labor, time, and other consumables that are used to construct and maintain the structure. Ideally, the role of structural design is straight forward. It is the transformation of the effects of various environmental and man-made actions (including constraints on materials, dimensions and cost etc.) into the appropriate material specifications, structural member sizes, and arrangements (Fig. 1).</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-rFbfV1tz1AM/XaNJxAU8qgI/AAAAAAAAHi0/5uHfKNRr5O0FYQ0ikDOByHzWQSLqKpUXQCNcBGAsYHQ/s1600/Conceptual_role_structural_design%2528Engineeersdaily.com%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="The Design Objectives and Philosophy - A Historical Overview" border="0" data-original-height="171" data-original-width="1200" height="90" src="https://1.bp.blogspot.com/-rFbfV1tz1AM/XaNJxAU8qgI/AAAAAAAAHi0/5uHfKNRr5O0FYQ0ikDOByHzWQSLqKpUXQCNcBGAsYHQ/s640/Conceptual_role_structural_design%2528Engineeersdaily.com%2529.jpg" title="The Design Objectives and Philosophy - A Historical Overview" width="640" /></a></td></tr>
<tr><td class="tr-caption"><span style="font-size: small;"><b>Figure 1</b> The conceptual role of structural design.</span></td></tr>
</tbody></table>
<div style="text-align: justify;">
The basic objective is to produce a structure capable of resisting all applied loads without failure and excessive deformations during its anticipated life. The very first output of any engineering design process is a description of what is to be manufactured or built, what materials are to be used, what construction techniques are to be employed, and an account of all necessary specifications as well as dimensions (which are usually presented in the form of drawings). The second output is a rational justification or explanation of the design proposal developed based on either full-scale tests, experiments on small physical models, or the mathematical solution of detailed analytical models representing the behavior of real structures.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
The process of structural design has passed through a long and still continuous phase of improvements, modifications, and breakthroughs in its various research areas. The structural analysis and design philosophies for new and existing buildings have a fascinating history. Perhaps, the first ever achievement in the history of structural design was the “confidence” by virtue of which early builders were able to convince themselves that the resulting structure could, indeed, be built and perform the intended function for the entirety of its intended life. Hence, the job of the very first engineers can be thought of as “to create the confidence to start building”. Over the course of the history, various scientists, mathematicians, and natural philosophers presented revolutionary ideas which resulted in improved understanding of structures and built environment. With the developments in different areas of practical sciences, the task of building <a href="http://www.engineersdaily.com/2014/04/steps-in-design-process.html" target="_blank">design</a> was gradually divided among more and more professionals depending upon aesthetic considerations, intended functions, materials, optimum utilization of space, lighting, ventilation, and acoustic preferences. The visual appearance, sense of space, and function (or the architecture) became a distinct concern during the 15th and 16th centuries. About a century later, designers first began to think about the load bearing aspects of structures in terms of self-weight and other sources of expected loading. Thinking separately about the role of individual materials and resulting structures grew during the late 17th and 18th centuries following Galileo’s work. The idea that the aesthetics should be given proper importance independent of the materials and load-bearing characteristics of the structure prevailed during the late 19th and the early 20th centuries.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
Table 1 presents a brief timeline of some of the major developments which led to modern techniques and methodologies for analyzing and designing structures.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<div style="text-align: center;">
<b>Table 1</b> Important Historical Developments Related to Structural Analysis and <a href="http://www.engineersdaily.com/2014/04/steps-in-design-process.html" target="_blank">Design</a><br />
<table border="0" cellpadding="0" cellspacing="0" class="MsoTableGrid" style="border-collapse: collapse; border: none; mso-border-insideh: none; mso-border-insidev: none; mso-padding-alt: 0in 5.4pt 0in 5.4pt; mso-yfti-tbllook: 1184;">
 <tbody>
<tr>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: none; border-top: solid windowtext 1.0pt; mso-border-bottom-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: 0.0001pt; text-align: center;">
<b>Year (CE)</b></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: none; border-top: solid windowtext 1.0pt; mso-border-bottom-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: 0.0001pt; text-align: center;">
<b>Development</b></div>
</td>
 </tr>
<tr>
  <td style="border: none; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1452 - 1519</div>
</td>
  <td style="border: none; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
Earliest contributions from Leonardo da Vinci</div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1638</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
<span lang="EN-US">Galileo
  Galilei examined the failure of simple structures and published his book “Two
  New Sciences”<o:p></o:p></span></div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1660</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
<span lang="EN-US">Robert
  Hooke presented the Hooke’s law which is the basis for elastic structural
  analysis<o:p></o:p></span></div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1687</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
<span lang="EN-US">Isaac
  Newton published his document “Principia Mathematica” containing the famous
  Newton’s laws of motion<o:p></o:p></span></div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1750</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: 0.0001pt;">
<span lang="EN-US">Leonhard
  Euler and Daniel Bernoulli developed Euler_Bernoulli <o:p></o:p></span><a href="http://www.engineersdaily.com/2014/01/beam-structures-classical-and-advanced.html" target="_blank">beam theory</a></div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1700-82</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
Daniel Bernoulli introduced the principle of
  virtual work</div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1707-83</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
Leonhard Euler developed the theory of buckling
  of columns</div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1826</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
<span lang="EN-US">Claude-Louis
  Navier published a document analyzing the elastic behavior of structures<o:p></o:p></span></div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1873</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
<span lang="EN-US">Carlo
  Alberto Castigliano presented his theorem for computing displacement as partial
  derivative of the strain energy<o:p></o:p></span></div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1874</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
Otto Mohr formalized the idea of a statically
  indeterminate structures</div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1922</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
<span lang="EN-US">Timoshenko
  corrects the Euler_Bernoulli beam equation and presented “Timoshenko’s <a href="http://www.engineersdaily.com/2011/01/design-of-reinforced-concrete-beams-per.html" target="_blank">Beam</a>
  Theory”<o:p></o:p></span></div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1936</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
<span lang="EN-US">Hardy
  Cross developed the moment distribution method, an important innovation in the
  analysis and design of continuous frames<o:p></o:p></span></div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1941</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
<span lang="EN-US">Alexander
  Hrennikoff solved the discretization of plane elasticity problems using the
  lattice framework<o:p></o:p></span></div>
</td>
 </tr>
<tr>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1942</div>
</td>
  <td style="padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
<span lang="EN-US">R.
  Courant presented solution of problems by dividing a domain into finite
  subregions<o:p></o:p></span></div>
</td>
 </tr>
<tr>
  <td style="border-bottom: solid windowtext 1.0pt; border: none; mso-border-bottom-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 63.9pt;" valign="top" width="107"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
1956</div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border: none; mso-border-bottom-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 394.4pt;" valign="top" width="657"><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; text-align: justify;">
<span lang="EN-US">J.
  Turner, R. W. Clough, H. C. Martin, and L. J. Topp introduces the term
  “finite element method” and published work which is widely recognized as the
  first comprehensive treatment of the method<o:p></o:p></span></div>
</td>
 </tr>
</tbody></table>
</div>
</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
It is worth noting that historically an understanding of <a href="http://www.engineersdaily.com/2014/05/how-loads-flow-through-building.html" target="_blank">how structures work</a> was never a phenomenon that required detailed knowledge of mathematical procedures and laws of mechanics. A common misconception is that various new structural forms and shapes were first devised by mathematicians (and experts of geometry) and later taken up by builders and engineers. In fact, the opposite is true, with perhaps just one exception, i.e., the hyperbolic paraboloid (whose structural properties were discovered in 1930s). In the last few centuries, artists, sculptors, and builders have displayed a remarkable understanding and skill of converting materials into structures (some of which are still standing today remarking the testimony of their expertise).</div>

Structural Design Objectives and Philosophy - A Historical Overview

Since the start of the formal approaches and procedures for carrying out the structural design, there have been many developments in the un...

An Overview of Structural Types

<div style="text-align: justify;">
The word structure (pronounced as “strək(t)SHər”) is a noun as well as a verb. As a noun, it means “<i><b>the arrangement of and the relations between parts or elements of something complex,</b></i>” and as a verb it refers to the process to “<b><i>construct or arrange according to a plan; give a pattern or organization.</i></b>” This term is used extensively in literature, and many disciplines signify these properties and processes.<br />
<br /></div>
<div style="text-align: justify;">
When applied to the physical and built environment, the term “structure” means an assemblage of physical components and elements, each of which could further be a structure in itself, signifying the complexity of the system. The discipline of “<b><i>Structural Engineering</i></b>” refers to the verb part of the definition, dealing with the ways to arrange and size a system of components for construction according to a plan and serving the intended purpose. The primary purpose of any structure is to provide a stable, safe, and durable system that supports the desired function within the physical environment, of which the structure is a part of. The role of the structural engineer, therefore, is to “<b><i>conceive, analyze, and design</i></b>” the structure to serve its purpose.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<a href="https://1.bp.blogspot.com/-DX-CbLZS9_E/XaNEbUUTasI/AAAAAAAAHio/ecN3Oi65QZsQ8SA-Ad2zVPU97MGNjuDjACNcBGAsYHQ/s1600/STRUCTURAL_TYPES%2528www.engineersdaily.com%2529.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em; text-align: center;"><img alt="An Overview of Structural Types" border="0" data-original-height="1196" data-original-width="1600" height="297" src="https://1.bp.blogspot.com/-DX-CbLZS9_E/XaNEbUUTasI/AAAAAAAAHio/ecN3Oi65QZsQ8SA-Ad2zVPU97MGNjuDjACNcBGAsYHQ/s400/STRUCTURAL_TYPES%2528www.engineersdaily.com%2529.jpg" title="An Overview of Structural Types" width="400" /></a>There is hardly any aspect of our built environment or human activity that does not rely on physical <a href="http://www.engineersdaily.com/2014/01/dynamics-of-structures-by-anil-kchopra.html" target="_blank">structures</a>. Buildings that provide useful places to live and work, bridges that provide us means to move across obstacles, factories that are needed to manufacture almost everything we need, dams to store water to generate power and irrigate lands, transmission towers to distribute electricity; all require structures to function, and structural engineers to design such structures. The role and importance of structural engineering and structural engineers is often underestimated and misunderstood. While a well-conceived and well-designed structure is the backbone of our built environment, a poorly conceived, designed, or constructed structure poses a serious hazard to the safety and well being of people and property. Collapse or failure of structures can claim a large number of lives and result in extensive economic loss. The role of structural engineers is, therefore, critical for overall economic development as well as for improving the community resilience to disasters.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
The physical structure, or structure for brevity, can be assembled in infinite ways using very few basic element types or forms, some of which are shown in Fig. 1.1. As is evident, these are derived from or are consistent with basic geometric primitives such as line, curve, plane, surface, and solid. This compatibility can often be used to blend the form, function, and structure.</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: justify;"><tbody>
<tr><td style="text-align: center;"><span style="margin-left: auto; margin-right: auto;"><img alt="The basic member types and forms that can be used to create structural systems." border="0" data-original-height="277" data-original-width="1340" height="132" src="https://1.bp.blogspot.com/-ZAUU7D1v23U/XaM8CAKiOmI/AAAAAAAAHiM/YgTbM3P5VtEOHIXyHbBSZmIbcop_rXzSQCNcBGAsYHQ/s640/Basic_member_types_Engineersdaily.png" title="The basic member types and forms that can be used to create structural systems." width="640" /></span></td></tr>
<tr><td class="tr-caption"><div style="text-align: center;">
<b style="font-size: medium;">Figure 1.1</b><span style="font-size: small;"> The basic member types and forms that can be used to create structural systems.</span></div>
</td><td class="tr-caption"></td><td class="tr-caption"></td></tr>
</tbody></table>
<div style="text-align: justify;">
The assemblage of these components can be of many types and configurations. Some are made entirely of the skeleton-type members, some from surface-type members, and some from solid-type members, but most structures are a combination of more than one member type. Based on the member types, the structures can be broadly categorized as</div>
<div style="text-align: justify;">
<ul>
<li><a href="http://www.engineersdaily.com/2016/03/use-of-cables-in-structures.html" target="_blank">cable structures</a></li>
<li>skeletal structural</li>
<li>spatial structures</li>
<li>solid structures, and</li>
<li>a combination of the aforementioned categories.</li>
</ul>
</div>
<div style="text-align: justify;">
<b><span style="color: #cc0000; font-size: large;">Cable Structures: Using Cables as the Main Member Type</span></b></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
These <a href="http://www.engineersdaily.com/2014/02/book-elements-of-theory-of-structures-jacquesheyman.html" target="_blank">structures</a> primarily transfer forces and internal actions through tension in individual cables or a set of cables. The shapes or geometry of cable profile often govern the behavior. Examples of such structures are:</div>
<div style="text-align: justify;">
<ul>
<li>Cable nets and fabric structures</li>
<li>Cable stayed structures</li>
<li>Cable suspended structures</li>
</ul>
</div>
<div style="text-align: justify;">
<b><span style="color: #cc0000; font-size: large;">Skeletal Structures: Using Beam-Type Members</span></b></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
These <a href="http://www.engineersdaily.com/2012/08/design-of-concrete-structures-14th.html" target="_blank">structures</a> are composed of bar members that mainly resist the <a href="http://www.engineersdaily.com/2014/05/how-loads-flow-through-building.html" target="_blank">loads and forces through a combination of tension, compression</a>, bending, shear, torsion, and warping. Such skeletal members are often called ties, struts, beams, columns, and girders. Typical application of skeletal <a href="http://www.engineersdaily.com/2014/01/dynamics-of-structures-by-anil-kchopra.html" target="_blank">structures</a> can be found in the following:</div>
<div style="text-align: justify;">
<ul>
<li><a href="http://www.engineersdaily.com/2011/01/3-methods-for-truss-analysis.html" target="_blank">Truss structures</a></li>
<li>Framed structures</li>
<li>Grid and grillage structures</li>
</ul>
</div>
<div style="text-align: justify;">
<b><span style="color: #cc0000; font-size: large;">Spatial Structures: Using the Membrane/Plate/Shell-Type Members</span></b></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
These are <a href="http://www.engineersdaily.com/2017/11/failures-of-structures-due-to-inappropriate-assessment-of-critical-force-paths.html" target="_blank">structures</a> created by spatial or surface type of elements and they transfer loads through a combination of bending, compression, torsion, and in-plane and out-of-plane shear of the element surface. The cross-sections of such members are generally rectangular. Examples of such structures include:</div>
<div style="text-align: justify;">
<ul>
<li>General shell <a href="http://www.engineersdaily.com/2014/04/steps-in-construction-of-reinforced-concrete-structures.html" target="_blank">structures</a></li>
<li>Dome-type structures</li>
<li>Slab, wall structures</li>
<li>Silos, chimneys, and stacks</li>
<li>Box girder bridges</li>
</ul>
</div>
<div style="text-align: justify;">
Sometimes, surface members and structures can be created by using a large number of skeletal members, covered by a skin or cladding, combining the fabric, cable, and bars to create surfaces.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<b><span style="color: #cc0000; font-size: large;">Solid Structures: Using the Solid-Type Members</span></b></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
These structures comprise of solid bodies or members in which the forces or loads are transferred through the member bodies. Such members or structures do not have a cross-section in the conventional sense. Some of the structures are:</div>
<div style="text-align: justify;">
<ul>
<li>Dams, thick arches, thick tunnels</li>
<li>Pile caps, thick footings, thick slabs, pier heads, large joints, etc.</li>
</ul>
</div>
<div style="text-align: justify;">
<b><span style="color: #cc0000; font-size: large;">Mixed Structures: Using One or More of the Basic Element Types</span></b></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
Most often, the real <a href="http://www.engineersdaily.com/2014/02/spreadsheet-wind-loading-analysis-for.html" target="_blank">structures</a> are composed of one or more types of basic elements. For example, a typical building is made of columns and beams (skeletal), slabs and walls (shell), footings (solid) structures, etc.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
There are several other types of structures that are either a combination of the basic forms or especially developed for a particular application or usage. These include stressed ribbon bridges, fabric structures, skeleton spiral structures, floating offshore <a href="http://www.engineersdaily.com/2013/05/retrofitting-design-of-building.html" target="_blank">structures</a>, pneumatically inflated structures etc.</div>

An Overview of Structural Types

The word structure (pronounced as “strək(t)SHər”) is a noun as well as a verb. As a noun, it means “ the arrangement of and the relations b...

Damp proofing of Slabs on Ground

<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div style="text-align: justify;">
The slabs-on-ground does not require high protection against water penetration and moisture in arid regions that does not have soils or have any sort of drainage problems.<br />
<br />
This precaution is not necessary if the area does not have irrigation activities going on nearby. This is the case unless the building code of that regions requires treatment.<br />
<br />
But for all site conditions other than mentioned above, it is essential to have water proofing or damp proofing for the slabs constructed on grounds.<br />
<br />
As per ACI 302.IR-89, there is no need for damp proofing or water proofing nor vapor retarders on sites that are well drained or those sites under the following conditions:<br />
<ol>
<li>The site has water table level very low from the ground surface</li>
<li>A substratum of coarse aggregate that is freely draining is installed</li>
<li>A floor covering is provided to the slab that is not affected by the moisture.</li>
</ol>
<h3>
<span style="color: #cc0000;">Damp Proofing of Slabs–on–Ground</span></h3>
The damp proofing of slabs constructed on ground can be done either below or above the surface. Mostly, the damp proofing is installed below the surface of the slab. Mostly plastic film of vapor retarders is employed below the slab surface as a damp proofing membrane.<br />
<br />
The figure-1 below shows the installation of a vapor retarder over the surface of gravel substrate. The vapor retarders are sealed to the foundation wall as shown. This will provide continuity in the placement.<br />
<br />
In order to avoid the penetration of sheet, brick chairs are employed other than the wire chairs.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-ZKyPgfyjZ_E/WiSDgImVOMI/AAAAAAAAHWk/i96sOrMySosxftn09WXNNuD7wObnyUAZwCLcBGAs/s1600/plastic-vapor-retarder-slabs-on-ground.jpg" style="margin-left: auto; margin-right: auto;"><img alt="Tamped grave substrate_ engineersdaily.com" border="0" data-original-height="326" data-original-width="386" height="270" src="https://1.bp.blogspot.com/-ZKyPgfyjZ_E/WiSDgImVOMI/AAAAAAAAHWk/i96sOrMySosxftn09WXNNuD7wObnyUAZwCLcBGAs/s320/plastic-vapor-retarder-slabs-on-ground.jpg" title="Tamped grave substrate_ engineersdaily.com" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Fig.1. The plastic vapor retarders are placed above the grave substrate that is tamped.</span></td></tr>
</tbody></table>
<div style="text-align: center;">
</div>
When wood flooring has to be provided above the slabs on ground, the damp proofing is done over the surface of the floor. The damp proofing over the slab top surface is permitted only under the following conditions, when:<br />
<ol>
<li>The water table is at least 12 inches below the slab surface</li>
<li>Installation of footing drains is carried out</li>
</ol>
The slabs-on ground with wooden flooring on the top will ask for damp proofing unless the above conditions are satisfied.<br />
<br />
The figure-2 below shows the installation of wooden flooring over the slabs that are constructed on ground.<br />
<br />
The wood flooring span sleepers will separate the surface from the bottom slab as shown in figure-2. The damp proofing can be applied to the slab only under the sub soil conditions mentioned above.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img alt="Wooden Flooring Above Slabs-on-Ground_engineersdaily.com" border="0" data-original-height="281" data-original-width="316" src="https://2.bp.blogspot.com/-9Z8JmxbADwo/WiSER3_halI/AAAAAAAAHWs/ZN8tF2jPNpojFvwRUmkl5tt-y2wL4haCwCLcBGAs/s1600/wooden-flooring-above-slabs-on-ground.jpg" style="margin-left: auto; margin-right: auto;" title="Wooden Flooring Above Slabs-on-Ground_engineersdaily.com" /></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Fig.2.Wooden Flooring Above Slabs-on-Ground</span></td></tr>
</tbody></table>
<br />
In the figure-2, an air space is created between the wooden flooring and the slabs constructed. This must be vented at the junctions so that the water penetration due to water vapor migration is avoided. This will help in maintaining an equal relative humidity both above and below the surface of the wooden flooring provided.<br />
<br />
The top surface damp proofing of the slabs constructed on ground will be interrupted by the partitions and the columns present. Vapor retarders constructed will be interrupted by these extra elements bringing a loss of integrity of the damp proofing system.<br />
<br />
The figure -3 below shows the same. Under such situations, the best alternative is to have damp proofing or water proofing under the slab.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img alt="The column interrupting the vapor retarder placed above a slab-on-ground_engineersdaily.com" border="0" data-original-height="250" data-original-width="371" height="215" src="https://2.bp.blogspot.com/-4Mr1jmLyCic/WiSE1_2ydgI/AAAAAAAAHW0/xzHPGsV7p4E1IlrXbipw-x0gr4h_as6gACLcBGAs/s320/vapor-retarder-placed-above-slabs-on-ground.jpg" style="margin-left: auto; margin-right: auto;" title="The column interrupting the vapor retarder placed above a slab-on-ground_engineersdaily.com" width="320" /></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Fig.3. The column interrupting the vapor retarder placed above a slab-on-ground</span></td></tr>
</tbody></table>
<h3>
<span style="color: #cc0000;">Risk in Using Vapor Retarders as a Waterproofing Solution</span></h3>
The substitution of vapor retarders instead of water proofing will welcome risks. The performance of the vapor retarder is dependent on the integrity of the film as well as the way it is seamed. The maintenance of a vapor retarder seam integrity in field condition is very difficult to attain in a slab on ground construction.<br />
<br />
The use of wooden or vinyl coverings too make the vapor retarders into risk. Other risk parameters are the use of wall – sensitive adhesives. Under these situations, it is most preferred to have a heavy-duty panel or water proofing to be installed than waiting for the loss caused by the complete replacement of moisture damaged floor.<br />
<br />
As shown in figure-2, the attachment of sleepers to the slabs-on-ground must be carried out with the help of water resistant adhesives instead of mechanical anchors.<br />
<br />
The use of nails and other mechanical anchors will result in puncture of vapor retarders that is located on the top surface of the slab.</div>
<div style="text-align: justify;">
<br />
<h3>
<span style="color: #cc0000;">Considerations in Damp Proofing Slabs on Ground</span></h3>
When the top surface of the slab is subjected to damp proofing, the slab should have a substratum that is of a granular material. This layer of properly graded aggregate will help in preventing the rise of moisture (mainly by the principle of capillary action).<br />
<br />
It is advised not to have a vapor retarder below the slab surface by using suspenders and other belts along with having a top surface damp proofing. The residual moisture in the concrete slabs can result in vapor pressure that can disband the vapor retarder and result in rupture.<br />
<br />
It is not appropriate to have too many floor finishes and coatings. This is because the concrete is moisture sensitive. Moisture sensitive adhesives can be used as a mode of moisture resistance.<br />
<br />
Liquid applied coatings in concrete slabs on ground have resulted in moisture in concrete. The following conditions can result in high level moisture contents:<br />
<ol>
<li>For those slabs that are cast on a grade with no proper functioning of the under-slab vapor retarders.</li>
<li>Conditions when the suspended slabs are cast over the non – vented steel formworks.</li>
<li>The conditions where the suspended slabs are constructed over the occupancies that possess higher relative humidity. These includes elements like commercial kitchen and swimming pools.</li>
<li>The installation of suspended slabs over the crawl spaces that are unvented.</li>
<li>The slabs with lightweight aggregates.</li>
<li>The slabs that used a water cement ration in excess of 0.55 (w/c = 0.55).</li>
<li>The slabs that cured in a period less than 90 day.</li>
</ol>
The manufactures of the floor finishes or damp proofing coatings highly follow the requirement of testing the concrete slab before the installation of any membranes. This testing will ensure that the moisture content in the slab is within the susceptible limits and won’t result in any failure.<br />
<br />
The Calcium Chloride Test as specified by ASTM F1869 is used to determine the Moisture Emission Rate (MVER). This is measured in pounds per thousand square feet within 24 hours. The accepted range of MVER is three to five pounds.<br />
<br />
The internal relative humidity in the structure is obtained by means of a hygrometer by placing probes in concrete. This is as per ASTM F710 and the established rate is 75 percent.<br />
<br />
This result can be achieved within 1 month of drying time per inch of the concrete element tested. It recommends the installation of vapor retarders in the direction of concrete pouring.</div>

Damp proofing of Slabs on Ground

The slabs-on-ground does not require high protection against water penetration and moisture in arid regions that does not have soils ...

Steel Sheet Piling Works - Workflow Procedure for Site Engineers

<div style="text-align: justify;">
This brief article explains the work flow procedure for site engineeers to execute steel sheet piling works. The procedure details various steps and checks that are recommended to be followed for such activities.</div>
<div style="text-align: justify;">
<br /></div>
<h3 style="text-align: justify;">
<b><span style="color: #cc0000;">Method and safety</span></b></h3>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Piling contractors must be requested to provide a written method statement as appropriate for the piling operations. Find out what induction training and information specific to a method statement is provided by immediate site supervisors to piling operatives.</div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-bP3NcEdktIM/XHpMfocrHlI/AAAAAAAAHgE/vZs3lgmbkaYJB9xiNz0FmXebkffidemdgCLcBGAs/s1600/Sheet_pile_%2528engineersdaily.com%2529.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="Steel Sheet Piling Works - Workflow Procedure for Site Engineers" border="0" data-original-height="1196" data-original-width="1600" height="298" src="https://2.bp.blogspot.com/-bP3NcEdktIM/XHpMfocrHlI/AAAAAAAAHgE/vZs3lgmbkaYJB9xiNz0FmXebkffidemdgCLcBGAs/s400/Sheet_pile_%2528engineersdaily.com%2529.JPG" title="Steel Sheet Piling Works - Workflow Procedure for Site Engineers" width="400" /></a></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Note that cranes must be selected and used in accordance with CP3010 and with the Construction (Lifting Operations) Regulations 1998. A firm level base of adequate bearing value must be provided, or crane mats used.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Check that cores of pendant/bridle ropes are not fractured.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Any crane used for raising or lowering operatives must be fitted with a dead man’s handle and the descent must be effectively controlled; the latter may be achieved by power lowering. Properly constructed man-carrying cages, which are unable to spin or tip, must be used. The cages should be regularly and carefully inspected.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• All lifting appliances and gear must carry appropriate certificates of test and examination, and must be adequate for the job, paying particular attention to the risk of damage to gear by sharp edges.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• All personnel working on piling operations must wear safety helmets (helmets appropriate for piling work are now available with retaining strap and smaller peaks). Ear and eye protection should be provided.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Piling machine operators must be at least 18 years of age, trained, competent, medically fit and authorised by site management to operate the machine.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• When piling from a pontoon or adjacent to water, personnel must wear life jackets. Rescue equipment (e.g. a safety boat and lifebuoys with lifelines attached) must be kept ready for immediate use and enough operatives must know how to use it.</div>
<div style="text-align: justify;">
<br /></div>
<h3 style="text-align: justify;">
<b><span style="color: #cc0000;">Materials handling</span></b></h3>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• When splitting bundles of sheet piles, use chocks. If large quantities of piles are handled, the use of purpose-made strops and grips is advised.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Piles should not be stacked too high or in a cantilever position. Use spacers and chocks where necessary. Tubular piles should not be stacked more than four high and should be properly chocked.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• When lifting piles or piling hammers, use hand lines to control the load. Give due consideration to wind speed during the operation.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Check the dimensions and alignment of clutches. If necessary perform trial clutching of piles. This is advisable for Z-shaped pile sections where the clutch is less positive than on trough sections (e.g. Larssen piles).</div>
<div style="text-align: justify;">
<br /></div>
<h3 style="text-align: justify;">
<b><span style="color: #cc0000;">Gate systems</span></b></h3>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
See Fig 1.</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-88ZGM0VUFbM/XHpKVouWs6I/AAAAAAAAHf4/i-h_X3HLmVM_Xkv-2WfW0B26GwN4imzqwCLcBGAs/s1600/Steel%2BSheet%2BPiling%2BWorks%2B-%2BWorkflow%2BProcedure%2Bfor%2BSite%2BEngineers%2B%2528engineersdaily.com%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Gate system using concrete bases (showing piling, the use of hanger brackets and the provision of a safety walkway)." border="0" data-original-height="527" data-original-width="666" height="506" src="https://2.bp.blogspot.com/-88ZGM0VUFbM/XHpKVouWs6I/AAAAAAAAHf4/i-h_X3HLmVM_Xkv-2WfW0B26GwN4imzqwCLcBGAs/s640/Steel%2BSheet%2BPiling%2BWorks%2B-%2BWorkflow%2BProcedure%2Bfor%2BSite%2BEngineers%2B%2528engineersdaily.com%2529.jpg" title="Gate system using concrete bases (showing piling, the use of hanger brackets and the provision of a safety walkway)." width="640" /></a></td></tr>
<tr><td class="tr-caption"><span style="font-size: small;"><b>Figure 1.</b> Gate system using concrete bases (showing piling, the use of hanger brackets and the provision of a safety walkway).</span></td></tr>
</tbody></table>
<div style="text-align: justify;">
• Positioning (pitching) and driving sheet piling is usually done by using a temporary supporting structure (gate). This is made up of heavy steel or timber H-frames supporting horizontal-heavy H-beam guides. The H-frames can be supported on heavy steel spreaders or specially cast concrete blocks. Ensure an adequate foundation under these frames and bases to prevent subsidence and overturning during piling operations. This is particularly applicable during work in rivers, etc.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• If using concrete blocks ensure that they are suitably reinforced to withstand loads from lifting and shock loading. Vertical steel columns should have a good bottom fixing. Vertical timber should not be cast into the block but should be wedged and bolted. Where doubt exists over stability use guy lines or raking steel props.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• All horizontal gates with platforms over 2m high, or over any potentially dangerous areas, must be provided with adequate guardrails, toeboards and correct ladder access.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Ladders must be secured and extend at least lm above staging.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• If using a cantilever system, use a tie-back where possible, as well as kentledge to provide safe anchorage.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• When piling is progressing and temporary piles are used to support the gate system, use purpose-made brackets and bolt them to the piles. Any welding necessary should be carried out by competent welders.</div>
<div style="text-align: justify;">
<br /></div>
<h3 style="text-align: justify;">
<b><span style="color: #cc0000;">Pitching piles</span></b></h3>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• If shackle holes have to be burned in the pile, remove sharp burrs to prevent damage to shackle pins.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Use quick-release shackles wherever possible:</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
– the sheet pile must not be lifted vertically without first checking that the pin is properly engaged through the sheet</div>
<div style="text-align: justify;">
– do not use a pull rope less than 5mm diameter</div>
<div style="text-align: justify;">
– the length of rope used must be less than the length of the pile, to prevent the extra rope snagging and pulling the release for the shackle</div>
<div style="text-align: justify;">
– secure the rope around the sheet pile to prevent snagging</div>
<div style="text-align: justify;">
– if a special lifting eye is to be welded to the pile for angled pitching, the weld should have a factor of safety of at least 2.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Pitch long sheet piles with a pile threader, following the manufacturer’s guidance for use. Where this is not possible, use a pile pitching cage. The cage is normally hung from an adjacent pile, the operatives wearing safety harnesses hooked to the adjacent pile before the crane hook is removed from the cage.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• When feeding sheet piles through the top and bottom gates, use wood blocks or a bent bar. Never use a straight pinch bar, as fingers can easily be trapped. Use a spacer block between the guides to keep the leading free clutch in its correct alignment.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Where access and work is carried out from ladders:</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
– Clutching: the ladder must be placed in the valley of a previously placed pile; the ladder must be footed and when at the top of the ladder both hands are required for clutching, a safety belt must be worn and secured to the pile using a manlock.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
– Wedging: the ladder must be placed against the H-beam and footed wedges should be pre-placed on the beam. A 4 lb. lump hammer must be used as this can be swung with one hand but if two hands are required, a safety belt must be used with the lanyard wrapped around the H-beam or used with a manlock.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
Note: At all times safety helmets and footware must be worn. When working at height the helmet should be secured with retaining strap.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
• Changes in work method:</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
– The work method must not be changed without consultation of the senior site representative responsible for the piling operation.</div>
<div style="text-align: justify;">
– If windy conditions (e.g. over 30 mph gusts) make the handling of the sheet piles difficult, stop work until the senior site representative responsible for the piling operation has been consulted and a safe method of continuing the work has been devised.</div>

Steel Sheet Piling Works - Workflow Procedure for Site Engineers

This brief article explains the work flow procedure for site engineeers to execute steel sheet piling works. The procedure details various ...

Shallow Foundations - An Overview

<div style="text-align: justify;">
A shallow foundation is often selected when the structural load will not cause excessive settlement of the underlying soil layers. <br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-0_Nkp4QYDhU/XHpAmnbU8qI/AAAAAAAAHfs/O1-ybv5vOAYqKOm3MoP7FJoyTukywxYPACLcBGAs/s1600/shallow_foundations_%2528www.engineersdaily.com%2529.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Shallow Foundations - An Overview" border="0" data-original-height="1196" data-original-width="1600" height="478" src="https://1.bp.blogspot.com/-0_Nkp4QYDhU/XHpAmnbU8qI/AAAAAAAAHfs/O1-ybv5vOAYqKOm3MoP7FJoyTukywxYPACLcBGAs/s640/shallow_foundations_%2528www.engineersdaily.com%2529.jpg" title="Shallow Foundations - An Overview" width="640" /></a></div>
<br />
In general, shallow foundations are more economical to construct than deep foundations. Common types of shallow foundations are listed in Table 1 and described later:<br />
<br />
<div style="text-align: center;">
<b>Table 1. Types of shallow foundations</b></div>
</div>
<style type="text/css">
.tg  {border-collapse:collapse;border-spacing:0;}
.tg td{font-family:Arial, sans-serif;font-size:14px;padding:2px 5px;border-style:solid;border-width:0px;overflow:hidden;word-break:normal;border-top-width:1px;border-bottom-width:1px;border-color:black;}
.tg th{font-family:Arial, sans-serif;font-size:14px;font-weight:normal;padding:2px 5px;border-style:solid;border-width:0px;overflow:hidden;word-break:normal;border-top-width:1px;border-bottom-width:1px;border-color:black;}
.tg .tg-73oq{border-color:#000000;text-align:left;vertical-align:top}
</style>

<br />
<table class="tg">
  <tbody>
<tr>
    <th class="tg-73oq"><span style="font-family: inherit;">Category</span></th>
    <th class="tg-73oq"><span style="font-family: inherit;">Common Types</span></th>
    <th class="tg-73oq"><span style="font-family: inherit;">Comments</span></th>
  </tr>
<tr>
    <td class="tg-73oq" rowspan="7"><span style="font-family: inherit;">Shallow foundations</span></td>
    <td class="tg-73oq"><span style="font-family: inherit;">Spread footings</span></td>
    <td class="tg-73oq"><span style="font-family: inherit;">Spread footings (also called pad footings) are often square in plan view, are of uniform reinforced concrete thickness, </span><br />
<span style="font-family: inherit;">and are used to support a single column load located directly in the center of the footing.</span></td>
  </tr>
<tr>
    <td class="tg-73oq"><span style="font-family: inherit;">Strip footings</span></td>
    <td class="tg-73oq"><span style="font-family: inherit;">Strip footings (also called wall footings) are often used for load-bearing walls. They are usually long reinforced concrete</span><br />
<span style="font-family: inherit;">members of uniform width and shallow depth.</span></td>
  </tr>
<tr>
    <td class="tg-73oq"><span style="font-family: inherit;">Combined footings</span></td>
    <td class="tg-73oq"><span style="font-family: inherit;">Reinforced-concrete combined footings are often rectangular or trapezoidal in plan view, and carry more than one column load.</span></td>
  </tr>
<tr>
    <td class="tg-73oq"><span style="font-family: inherit;">Conventional slab-on-grade</span></td>
    <td class="tg-73oq"><span style="font-family: inherit;">A continuous reinforced-concrete foundation consisting of bearing wall footings and a slab-on-grade.</span><br />
<span style="font-family: inherit;">Concrete reinforcement often consists of steel rebar in the footings and wire mesh in the concrete slab.</span></td>
  </tr>
<tr>
    <td class="tg-73oq"><span style="font-family: inherit;">Posttensioned slab-on-grade</span></td>
    <td class="tg-73oq"><span style="font-family: inherit;">A continuous posttensioned concrete foundation. The posttensioning effect is created by tensioning steel tendons or cables</span><br />
<span style="font-family: inherit;">embedded within the concrete. Common posttensioned foundations are the ribbed foundation, California slab, and PTI foundation.</span></td>
  </tr>
<tr>
    <td class="tg-73oq"><span style="font-family: inherit;">Raised wood floor</span></td>
    <td class="tg-73oq"><span style="font-family: inherit;">Perimeter footings that support wood beams and a floor system. Interior support is provided by pad or strip footings. There is a</span><br />
<span style="font-family: inherit;">crawl space below the wood floor.</span></td>
  </tr>
<tr>
    <td class="tg-73oq"><span style="font-family: inherit;">Mat foundation</span></td>
    <td class="tg-73oq"><span style="font-family: inherit;">A large and thick reinforced-concrete foundation, often of uniform thickness, that is continuous and supports the entire structure.</span><br />
<span style="font-family: inherit;">A mat foundation is considered to be a shallow foundation if it is constructed at or near ground surface.</span></td>
  </tr>
</tbody></table>
<h3 style="text-align: justify;">
<b><span style="color: #cc0000;"><br /></span></b></h3>
<h3 style="text-align: justify;">
<b><span style="color: #cc0000;">1. Spread Footings, Combined Footings, and Strip Footings</span></b></h3>
<div style="text-align: justify;">
These types of shallow foundations are probably the most common types of building foundations. Figure 1 shows various types of shallow foundations.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-oMFGyDWJN5g/XHoqGBq7fTI/AAAAAAAAHfY/sNgRc4arZLoq77vClC7JDGiiuEq-hUe-wCLcBGAs/s1600/Examples_of_shallow_foundations%2528engineersdaily.com%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Figure 1. Examples of shallow foundations. (a) Combined footing; (b) combined trapezoidal footing; (c) cantilever or strap footing; (d) octagonal footing; (e) eccentric loaded footing with resultant coincident with area so soil pressure is uniform. (Reproduced from Bowles, 1982; McGraw-Hill, Inc.)" border="0" data-original-height="277" data-original-width="340" height="520" src="https://2.bp.blogspot.com/-oMFGyDWJN5g/XHoqGBq7fTI/AAAAAAAAHfY/sNgRc4arZLoq77vClC7JDGiiuEq-hUe-wCLcBGAs/s640/Examples_of_shallow_foundations%2528engineersdaily.com%2529.jpg" title="Figure 1. Examples of shallow foundations. (a) Combined footing; (b) combined trapezoidal footing; (c) cantilever or strap footing; (d) octagonal footing; (e) eccentric loaded footing with resultant coincident with area so soil pressure is uniform. (Reproduced from Bowles, 1982; McGraw-Hill, Inc.)" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: justify;"><b>Figure 1.</b> Examples of shallow foundations. (a) Combined footing; (b) combined trapezoidal footing; (c) cantilever or strap footing; (d) octagonal footing; (e) eccentric loaded footing with resultant coincident with area so soil pressure is uniform. (Reproduced from Bowles, 1982; McGraw-Hill, Inc.)<br />
<br /></td></tr>
</tbody></table>
<h3 style="text-align: justify;">
<span style="color: #cc0000;"><b>2. Mat Foundation</b></span></h3>
<div style="text-align: justify;">
Figure 2 shows various types of mat foundations. Based on economic considerations, mat foundations are often constructed for the following reasons (NAVFAC DM-7.2, 1982):</div>
<div style="text-align: justify;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-J7aGgSnZ9nU/XHoq9KoHC8I/AAAAAAAAHfg/QDBzNK2UtqQvJ45_LdUhhk8OAzVV25LxgCLcBGAs/s1600/Examples_of_mat_foundations%2528engineersdaily.com%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Figure 2. Examples of mat foundations. (a) Flat plate; (b) plate thickened under columns; (c) beam-and-slab; (d) plate with pedestals; (e) basement walls as part of mat. (Reproduced from Bowles, 1982; McGraw-Hill, Inc.)" border="0" data-original-height="274" data-original-width="342" height="512" src="https://2.bp.blogspot.com/-J7aGgSnZ9nU/XHoq9KoHC8I/AAAAAAAAHfg/QDBzNK2UtqQvJ45_LdUhhk8OAzVV25LxgCLcBGAs/s640/Examples_of_mat_foundations%2528engineersdaily.com%2529.jpg" title="Figure 2. Examples of mat foundations. (a) Flat plate; (b) plate thickened under columns; (c) beam-and-slab; (d) plate with pedestals; (e) basement walls as part of mat. (Reproduced from Bowles, 1982; McGraw-Hill, Inc.)" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b>Figure 2.</b> Examples of mat foundations. (a) Flat plate; (b) plate thickened under columns; (c) beam-and-slab; (d) plate with pedestals; (e) basement walls as part of mat. (Reproduced from Bowles, 1982; McGraw-Hill, Inc.)</td></tr>
</tbody></table>
<div style="text-align: justify;">
i. <i><b>Large individual footings.</b></i> A mat foundation is often constructed when the sum of individual footing areas exceeds about one-half of the total foundation area.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
ii. <i><b>Cavities or compressible lenses.</b></i> A mat foundation can be used when the subsurface exploration indicates that there will be unequal settlement caused by small cavities or compressible lenses below the foundation. A mat foundation would tend to span over the small cavities or weak lenses and create a more uniform settlement condition.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
iii. <i><b>Shallow settlements.</b></i> A mat foundation can be recommended when shallow settlements predominate and the mat foundation would minimize differential settlements.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
iv. <i><b>Unequal distribution of loads.</b></i> For some structures, there can be a large difference in building loads acting on different areas of the foundation. Conventional spread footings could be subjected to excessive differential settlement, but a mat foundation would tend to distribute the unequal building loads and reduce the differential settlements.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
v. <i><b>Hydrostatic uplift.</b></i> When the foundation will be subjected to hydrostatic uplift due to a high groundwater table, a mat foundation could be used to resist the uplift forces.<br />
<br /></div>
<h3 style="text-align: justify;">
<span style="color: #cc0000;"><b>3. Posttensioned Slab-on-Grade</b></span></h3>
<div style="text-align: justify;">
Posttensioned slab-on-grade is common in southern California and other parts of the United States. The most common uses of posttensioned slab-on-grade are to resist expansive soil forces or when the projected differential settlement exceeds the tolerable value for a conventional (lightly reinforced) slab-on-grade. For example, posttensioned slabs-on-grade are frequently recommended if the projected differential settlement is expected to exceed 0.75 in. (2 cm).</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
The Post-Tensioning Institute (1996) has prepared installation and field inspection procedures for posttensioned slab-on-grade. Posttensioned slab-on-grade consists of concrete with embedded steel tendons that are encased in thick plastic sheaths. The plastic sheath prevents the tendon from coming in contact with the concrete and permits the tendon to slide within the hardened concrete during the tensioning operations. Usually tendons have a dead end (anchoring plate) in the perimeter (edge) beam and a stressing end at the opposite perimeter beam to enable the tendons to be stressed from one end. However, it is often recommend that the tendons in excess of 100 ft (30 m) b stressed from both ends.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
Because posttensioned slab-on-grade perform better (i.e., less shrinkage related concrete cracking) than conventional slab-on-grade, they are more popular even for situations where low levels of settlement are expected. Posttensioned slab-on-grade has become common for situations where it is desirable to limit the amount and width of concrete shrinkage cracks.<br />
<br /></div>
<h3 style="text-align: justify;">
<b><span style="color: #cc0000;">4. Shallow Foundation Alternatives</span></b></h3>
<div style="text-align: justify;">
If the expected settlement for a proposed shallow foundation is too large, then other options for foundation support or soil stabilization must be evaluated. Some commonly used alternatives are as follows:</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
i. <b><i>Grading.</i></b> Grading operations can be used to remove the compressible soil layer and replace it with structural fill. Usually the grading option is only economical if the compressible soil layer is near the ground surface and the groundwater table is below the compressible soil layer or the groundwater table can be economically lowered.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
ii. <b><i>Surcharge.</i></b> If the site contains an underlying compressible cohesive soil layer, the site can be surcharged with a fill layer placed at the ground surface. Vertical drains (such as wick drains or sand drains) can be installed in the compressible soil layer to reduce the drainage paths and speedup the consolidation process. Once the compressible cohesive soil layer has had sufficient consolidation, the fill surcharge layer is removed and the building is constructed.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
iii. <i><b>Densification of soil.</b></i> There are many different methods that can be used to densify loose or soft soil. For example, vibro-flotation and dynamic compaction are often effective at increasing the density of loose sand deposits. Another option is compaction grouting, which consists of intruding a mass of very thick consistency grout into the soil, which both displaces and compacts the loose soil.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
iv. <b><i>Floating foundation.</i></b> A floating foundation is a special type of deep foundation where the weight of the structure is balanced by the removal of soil and construction of an underground basement.</div>

Shallow Foundations - An Overview

A shallow foundation is often selected when the structural load will not cause excessive settlement of the underlying soil layers. In ...

Selection of Foundation Type

<div style="text-align: justify;">
Selection of the most suitable and effficient type of foundation for a particular structure is a tricky step in the whole structural design process. A well designed super structure will be a waste of time, money and efforts if due attention is not give to the choice of right type of sub structure. This brief article enlists some the most important deciding factors during the process. </div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-BfmA7V0BNHc/XHkxVeyWfRI/AAAAAAAAHfM/aye7bm6ITAAaiOTLVi_5prAcEApyf2gDwCLcBGAs/s1600/Selection_of_foundation_type%2528www.engineersdaily.com%2529.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Selection of Foundation Type" border="0" data-original-height="1196" data-original-width="1600" height="298" src="https://2.bp.blogspot.com/-BfmA7V0BNHc/XHkxVeyWfRI/AAAAAAAAHfM/aye7bm6ITAAaiOTLVi_5prAcEApyf2gDwCLcBGAs/s400/Selection_of_foundation_type%2528www.engineersdaily.com%2529.jpg" title="Selection of Foundation Type" width="400" /></a></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
The selection of a particular type of foundation is often based on a number of factors, such as:</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
1. Adequate depth. The foundation must have an adequate depth to prevent frost damage. For suchfoundations as bridge piers, the depth of the foundation must be sufficient to prevent undermining by scour.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
2. Bearing capacity failure. The foundation must be safe against a bearing capacity failure.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
3. Settlement. The foundation must not settle to such an extent that it damages the structure.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
4. Quality. The foundation must be of adequate quality so that it is not subjected to deterioration, such as from sulfate attack.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
5. Adequate strength. The foundation must be designed with sufficient strength that it does not fracture or break apart under the applied superstructure loads. The foundation must also be properly constructed in conformance with the design specifications.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
6. Adverse soil changes. The foundation must be able to resist long-term adverse soil changes. An example is expansive soil, which could expand or shrink causing movement of the foundation and damage to the structure.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
7. Seismic forces. The foundation must be able to support the structure during an earthquake without excessive settlement or lateral movement.</div>

Selection of Foundation Type

Selection of the most suitable and effficient type of foundation for a particular structure is a tricky step in the whole structural design...

Best Engineering/Scientific/Graphing Calculators

<div style="text-align: justify;">
Choosing the right calculator for your needs can be a tough job. But you can compare some of the best calculators in the industry with our brief but useful list below. The features and number of functions vary from calculator to calculator. Some have around a hundred functions while others have several hundred. Some calculators have bright, well lit screens, while others are more difficult to see but users favor the style. Depending upon your needs, you’re sure to find the calculator for you on this list.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<a href="https://amzn.to/2NaD5ys" target="_blank">1. Texas Instruments TI-84 Plus CE Plum Graphing Calculator</a></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: right;">
<img alt="" border="0" height="1" src="//ir-na.amazon-adsystem.com/e/ir?t=tsx09-20&l=am2&o=1&a=B078NFWPKK" style="border: none !important; margin: 0px !important;" width="1" />
</div>
<div style="text-align: justify;">
<div class="separator" style="clear: both; text-align: center;">
<a href="https://amzn.to/2NaD5ys" target="_blank"><img border="0" data-original-height="450" data-original-width="450" height="320" src="https://1.bp.blogspot.com/-t1EVV-JmS5Q/W66rMKEuGeI/AAAAAAAAHdw/x7sQHDosF1A6vpJS6EDDf0e0sDpGTluRgCLcBGAs/s320/TI%2B84%2BPLUS.jpg" width="320" /></a></div>
This graphing calculator has a very high resolution backlit display. It’s likely the highest quality display available on any scientific calculator. The calculator is lightweight and available in plum, red, denim, blueberry, gray, gold, silver and white. The battery may get weak quickly if you use it a lot. A huge benefit is the fast processor. It comes with a user guide and double sided cable. The only complaint that some users have is that the font is too small. It’s great for high school students taking advanced math. If you need to easily graph complicated expressions, this is the calculator for you.</div>
<div style="text-align: justify;">
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://amzn.to/2NaD5ys" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;" target="_blank"><img border="0" data-original-height="213" data-original-width="480" height="88" src="https://2.bp.blogspot.com/-lxxmHH9LdOo/W66r9RtR_8I/AAAAAAAAHd4/HZuLcROdjVIHHRkNxNWSk7VkcSKI_gxUACLcBGAs/s200/buynow-logo-bk.png" width="200" /></a></div>
<br /></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<br />
<br />
<br />
<br />
<a href="https://amzn.to/2xM2M3v" target="_blank">2. Casio fx-9750GII Graphing Calculator</a></div>
<div style="text-align: justify;">
<div class="separator" style="clear: both; text-align: center;">
<a href="https://amzn.to/2xM2M3v" target="_blank"><img border="0" data-original-height="350" data-original-width="350" height="320" src="https://1.bp.blogspot.com/-hi_NjXsFdMk/W66vBA6jndI/AAAAAAAAHeM/6j3bmI23HKMYb0b9LLi9XEZ8LiXf-RdhACLcBGAs/s320/9750.jpg" width="320" /></a></div>
<br /></div>
<div style="text-align: justify;">
Create bar graphs and pie charts with ease. The screen is easy to read in a number of different lighting situations. Enjoy a high speed RAM CPU and USB connectivity, making it easy to share files. Some users have said that it’s not the easiest to program. However, the functions are easy to understand. It comes with a well organized user manual.<br />
<br /></div>
<div style="text-align: justify;">
<a href="https://amzn.to/2xM2M3v" target="_blank"><img border="0" data-original-height="213" data-original-width="480" height="88" src="https://2.bp.blogspot.com/-lxxmHH9LdOo/W66r9RtR_8I/AAAAAAAAHd4/HZuLcROdjVIHHRkNxNWSk7VkcSKI_gxUACLcBGAs/s200/buynow-logo-bk.png" width="200" /></a></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<a href="https://amzn.to/2N9GopI" target="_blank">3. HP HP50G 50g Graphing Calculator</a></div>
<div style="text-align: justify;">
<div class="separator" style="clear: both; text-align: center;">
<a href="https://amzn.to/2N9GopI" target="_blank"><img border="0" data-original-height="1500" data-original-width="817" height="320" src="https://4.bp.blogspot.com/-CTvYGCyKpYs/W66vXKEiEUI/AAAAAAAAHeU/1foCNeU9s0IalMaTJbN8rkA75KmYfbv2QCLcBGAs/s320/HP50g_engineersdaily.jpg" width="174" /></a></div>
</div>
<div style="text-align: justify;">
This calculator has 30% more screen space than the previous version and most other scientific calculators for that matter. It has a better keypad than the last model and is quipped with an SD card slot. You can choose between RPN, Algebraic, and Textbook data entry. Not that this graphing calculator uses a lot of battery power. The advantages of this calculator are the high range of functions and the ease of programmability.<br />
<br />
<a href="https://amzn.to/2N9GopI" target="_blank"><img border="0" data-original-height="213" data-original-width="480" height="88" src="https://2.bp.blogspot.com/-lxxmHH9LdOo/W66r9RtR_8I/AAAAAAAAHd4/HZuLcROdjVIHHRkNxNWSk7VkcSKI_gxUACLcBGAs/s200/buynow-logo-bk.png" width="200" /></a></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<a href="https://amzn.to/2zCUaO0" target="_blank">4. Casio fx-9860 GII</a> (<b><span style="color: #cc0000;">Engineersdaily's recommendation</span></b>)<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://amzn.to/2zCUaO0" target="_blank"><img border="0" data-original-height="1500" data-original-width="1059" height="320" src="https://1.bp.blogspot.com/-nyENqKryNqM/W66ui75kzJI/AAAAAAAAHeE/oBrfl8URYIsy7LmSP5iPJ9A2A26gfVcOwCLcBGAs/s320/9862_engineersdaily.jpg" width="225" /></a></div>
This versatile programmable calculator is very suir´table for complex jobs especially in exams where lots of calculations are needed under time pressure. Formulae can also be programmed easily. It also features a USB connection and comes handy with a cable to connect to your computer. More specs can be found at the link above.<br />
<a href="https://amzn.to/2zCUaO0" target="_blank"><img border="0" data-original-height="213" data-original-width="480" height="88" src="https://2.bp.blogspot.com/-lxxmHH9LdOo/W66r9RtR_8I/AAAAAAAAHd4/HZuLcROdjVIHHRkNxNWSk7VkcSKI_gxUACLcBGAs/s200/buynow-logo-bk.png" width="200" /></a></div>

Best Engineering/Scientific/Graphing Calculators

Choosing the right calculator for your needs can be a tough job. But you can compare some of the best calculators in the industry with our ...

Fire and Safety Features of High-Rise Buildings and Structures

<div style="text-align: justify;">
Fire and other safety features of high rise buildings and structures is essential. Types and concerns related to these features is discussed.<br />
<br />
The <a href="http://www.engineersdaily.com/2014/02/book-settlement-calculation-on-highrise-buildings-xiangfuchen.html" target="_blank">high-rise building</a> construction concept when compared with other buildings, possess certain features and characteristics that makes them unique and highlighting. The high-rise buildings are considered as the product of the modern evolution. It is filled and composed of sophisticated systems and essential components.<br />
<br />
Each of these systems carry out special roles either positive or negative. These elements have an effective role in the overall fire department’s operation.<br />
<br />
Most of the components in the high-rise construction focus on safety during emergency or fire risk. They are more focused on fire systems to protect the occupants.<br />
<br />
These will hence demand costlier building systems and unique fire safety codes. The fire and safety issues with different features available in the high-rise building is explained hereby.<br />
<br />
Over years, the high-rise buildings have garnered significant attention in the fire safety throughout the world. The multiple floors present in the high-rise building makes great number of persons to travel long vertical distances by the stair during an evacuation.<br />
<br />
The public regulations, the design of the building, the ownership, code bodies, the regional, local and federal governments are affected by the high-rise building safety.<br />
<br />
The high rise buildings are designed to be safe at all undesirable conditions. But when there is a need for a full scale evacuation, it will be necessary to take quick responsibility for their own safety and planned action from the fire fighters.</div>
<div style="text-align: justify;">
</div>
<div style="text-align: justify;">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img alt="Fire and Safety Features of High-Rise Buildings and Structures_engineersdaily.com" border="0" data-original-height="340" data-original-width="580" src="https://3.bp.blogspot.com/-4k1iICuRtyE/WiSHwRsmiFI/AAAAAAAAHXA/30peSbO8vWQ7N21-2VPPsva0JobpW27aACLcBGAs/s1600/fire-safety-high-rise-building-structures.jpg" style="margin-left: auto; margin-right: auto;" title="Fire and Safety Features of High-Rise Buildings and Structures_engineersdaily.com" /></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Fire and Safety Features of High-Rise Buildings and Structures</span></td></tr>
</tbody></table>
<h3>
<span style="color: #cc0000;">Construction Concerns in High-Rise Building Construction</span></h3>
When compared with other form of <a href="http://www.engineersdaily.com/2011/01/energy-efficient-design-of-buildings.html" target="_blank">building construction</a>, high rise building construction have a major focus on the building fire and emergency concerns. To understand this, the first major requirement is to study the number of floors of the building under consideration.<br />
<br />
The number of floors both above and below the grade have to be evaluated for the same purpose. The firefighting operations is very much dependent on how these levels are identified and labeled in the building.<br />
<br />
For example, if there is a floor which is numbered 13; it is found out whether there exist any other levels like the concourse levels or the mezzanines, or it is found that the floor 13 is where the mechanical level is located and have different mechanical levels. Or sometimes the floor has a penthouse level.<br />
<br />
An occurrence of a high-rise fire or any other emergency will ask many questions regarding the high-rise building construction features, that are available.<br />
<br />
Hence the Incident Commander (IC) have the role to assign different teams to conduct an ongoing reconnaissance. The team consists of group leaders and division supervisors. Most of the fire department consists of a system officer who is positioned inside the fire command center (FCC).<br />
<br />
The system Officer is responsible in the monitor of different building systems like the fire alarm panel, the HVAC system, the elevators etc. The system officer is the important source for the incident commander to gather the data and information of the building which are considered very critical.<br />
<br />
The quick determination of the age of high rise buildings and the generation which it falls is also identified by the IC. This is very important to know whether the building make use of any lightweight components, for example, any truss assemblies.<br />
<br />
This idea will give us an estimate on how long the fire fighters can operate inside the buildings with reasonable safety.</div>
<div style="text-align: justify;">
<br />
<h3>
<span style="color: #cc0000;">Concerns on the Structural System the Building Possess</span></h3>
The concerns or question that comes to mind during a fire operation is whether:<br />
<ol>
<li>The building is core type or not</li>
<li>If not Core type, what <a href="http://www.engineersdaily.com/2014/04/structural-systems-in-reinforced-concrete-buildings.html" target="_blank">structural system</a> do the building possess</li>
<li>If it’s a core type, is the core center or some other type</li>
<li>Does the building possess a central HVAC system?</li>
</ol>
This information will help in bringing a quality pre-fire plan. When you consider the use of high rise construction in the world, almost all countries possess high rise building to an appreciable range.<br />
<br />
The lack of proper resources and the time constraints will affect in bringing a quality pre-fire plan for the building. But many firms work for developing these pre-fire plan which are very expensive.<br />
<br />
It’s a matter of fact that most of the buildings do not possess a plan by themselves nor approach any other company for the same.</div>
<div style="text-align: justify;">
<br />
<h3>
<span style="color: #cc0000;">Concerns on Static and Dynamic Features of Building</span></h3>
Once the pre-fire plan is considered for a high-rise building, it will stay active until the features of the building remain static. This is hence the main issue because most of the high-rise buildings are dynamic.<br />
<br />
With demand, more and more up gradation is brought to the buildings. Any change on features of the building system will affect the plan and the considerations. Hence these plans must be updated accordingly.</div>
<div style="text-align: justify;">
<br />
<h3>
<span style="color: #cc0000;">Concerns on the Materials used in High Rise Building</span></h3>
In the case of a core type structural building, emphasis is on finding out what material forms the structural components, the core, the structural frame, the floor components; whether concrete or steel or both.</div>
<div style="text-align: justify;">
<br />
Most of the modern high-rise building construction consist of floors where the concrete is poured over a metal deck. Regarding this, the questions arise on:<br />
<ol>
<li>Whether the load of the floor is taken by the structural frame?</li>
<li>Is there any I – section to support the floors?</li>
<li>Is there any fire proofing material used to protect the steel components?</li>
</ol>
</div>
<div style="text-align: justify;">
Concerns regarding the roof construction of the building: The material type of the roof, the type of equipment on the roof, the load that is carried by these structural components are the concerns regarding the roof construction.<br />
<br />
In high rise construction, the question on whether the roof have the capacity to take the load of a helicopter is raised. Other concerns are on the roof obstructions.<br />
<br />
The roof with high parapet walls provide additional safety for the firefighters who are operating on the roof also the ones who have be evacuated. Shorter parapet won’t provide no protection in situations where the visibility is lost due to the smoke or during night operations.</div>
<div style="text-align: justify;">
<br />
<h3>
<span style="color: #cc0000;">Concerns with Fire Detection and The Protection Systems in High- Rise Buildings</span></h3>
It is very essential to determine and identify the fire detection and the protection system that is available in the building to bring the best fire safety plan.<br />
<br />
There may be different types of fire detection devices installed in the building. These include the smoke detectors, the heat detectors, manual pull stations, the rate of rise and etc. It is very essential to determine the location of the fire alarm in the building.<br />
<br />
If there is any indication from multiple alarms that are in different locations it fixes the probability of actual fire in the building. When multiple locations of alarms are heard it is recommended to check the lowest alarm.<br />
<br />
The sprinkler system in the building is identified if installed. The position or the location of the sprinkler system is very essential. It is also essential to determine the type of sprinkler system in the building; whether it is partial sprinkler protection, or full sprinkler protection or no sprinkler protection. A check on the operation of the sprinkler system has to be examined.</div>
<div style="text-align: justify;">
</div>
<div style="text-align: justify;">
<h3>
<span style="color: #cc0000;"><br /></span></h3>
<h3>
<span style="color: #cc0000;">Water Supply in High-rise construction</span></h3>
To construct a fire protection system in the high-rise building, it is very essential to have a comprehensive knowledge on the built-in fire protection systems. Water supply is an essential concern with the fire safety measure.<br />
<br />
The mode of water supply for fire protection system must be determined. Not only the source but also the water flow. The water supply equipment as a part of fire protection system will include the gravity tanks, fire pumps, the city water mains and other different components.<br />
<br />
In a situation where the primary water supply becomes insufficient or it fails to operate, a backup water supply will be served by the fire department connection (FDC) coming under the area and the locality.</div>
<div style="text-align: justify;">
<br />
<h3>
<span style="color: #cc0000;">Concerns with the Stairs in High-rise building during a Fire Emergency</span></h3>
Early Identification of number of stairs in the building must be considered. Most of the high-rise buildings will possess two stairs well that runs throughout the height of the building. But most probably one among the two will have the access towards the roof.<br />
<br />
In modern high-rise buildings, when the fire alarms of specific zones are activated, these primary stairwells are pressurized. In old buildings, under a fire emergency, one of the stairwell will behave like a smoke tower.<br />
<br />
Whatever be the type of stair, scissor type or return type, both are found to be critical under a fire emergency. All information regarding, which stair can be easily accessed for evacuation and which is easily occupied by the fire are very valuable during an emergency plan.<br />
<br />
Always a pre-plan during the good performance of the building itself it must be categorized that which stair is used for evacuation and which is the attack stair.</div>
<div style="text-align: justify;">
<br />
<h3>
<span style="color: #cc0000;">Concerns with the Elevators</span></h3>
All high-rise building will possess elevators. Large buildings will have elevators in more number that are arranged in separate banks that serves separate locations.<br />
<br />
Elevators can be considered as an essential parameter for the firefighters. They behave as valuable tools in emergency situations. Operational success is attained by accounting the number of elevators and their type, before undergoing the operation.</div>
<div style="text-align: justify;">
<br />
<h3>
<span style="color: #cc0000;">The HVAC Systems in High Rise buildings</span></h3>
Most of the modern high rise buildings are equipped with well modernized and sophisticated Heating ventilation and the air conditioning system.<br />
<br />
Many buildings are equipped with ventilation system to get rid of smoke and to control the air movement because of fire within the building.<br />
<br />
The first and the second generation high-rise building make use of horizontal ventilation. Any chance of smoke found, make them to open the windows. This way blocking of smokes was avoided. This strategy is not possible in the present day modern high rise buildings.<br />
<br />
The third-generation buildings where more of sealed ones. These were referred to as windowless buildings. This is not because of the absence of the windows in the building, but the fact that they are designed to be opened or easily broken out.<br />
<br />
In a third-generation building, a smoke generated will be collected in a remote area of the building. This problem is well solved by the installation of HVAC system. Sometimes the HVAC system can result in very tragic negative problems also.<br />
<br />
The problem of ventilation in high rise buildings is a great issue. Mostly the issue is with the smoke than with the fire problems. The smoke has resulted in countless injuries and deaths during most of the fires in the high-rise building.<br />
<br />
The issue with the ventilation in high rise buildings must be considered in the initial planning stage of the buildings, to reduce additional expense.</div>
<div style="text-align: justify;">
<br />
<h3>
<span style="color: #cc0000;">Concerns with the Utilities in The High-Rise Buildings</span></h3>
The daily utilities in the building like the electricity, water, steam and the natural gas have a very important role in the daily operations of a given building. These operations do have an important role during a fire emergency. A control of these operations is a simple matter and are of less effort which can promote large safety.</div>
<div style="text-align: justify;">
<br />
<h3>
<span style="color: #cc0000;">Generalization of Fire Damage in High Rise Buildings</span></h3>
The fire damage will be categorized under three ways.<br />
<ol>
<li>The detrimental effect for the occupant’s life safety</li>
<li>Structural Damage</li>
<li>Damage to the properties-Non-structural damage</li>
</ol>
Among most of the fire incidents that have been recorded, it is observed that the injuries and the loss of life is less. What everyone wish is to bring a less effect on the property damages also.<br />
<br />
The migration of heat and the smoke within the high rise buildings is a great threat for the occupants within the building. Most of the death due to fire accidents are caused within the dwellings.<br />
<br />
The fire will result in the formation of toxic gases that is very dangerous to the human health. In such situations, the structural damages have least importance when compared with the life safety. After extinguishing the fire, it is found that the structure is subjected to water damage. The repair and the maintenance is a great economic loss.<br />
<br />
The high-rise buildings are stuffed with large equipment which are numerous are costly. Fire will bring lots of property loss due to these reasons. These reasons have resulted in the bankrupt of many companies as their production process was completely stopped and lost the market.<br />
<br />
There are many factors that affect the fire and safety concerns of a high-rise building. It is always recommended that how extreme be the fire damage, the measures and operations must bring life safety as the primary concern. This will ask for fire and building codes that will possess both passive and active fire protection systems in order to reduce the fire damages.</div>
<div style="text-align: justify;">
<br />
<h3>
<span style="color: #cc0000;">Performance Based Design for Structural Safety Against Fire</span></h3>
Performance based design concept is the design the buildings according to the main goals. PBD is hence regarded as one of the best solution for this problem of fire issues in structural point of view.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img alt="Different Performance Levels in Performance Based Design_engineersdaily.com" border="0" data-original-height="281" data-original-width="496" src="https://3.bp.blogspot.com/-hKcjZIYRlJ0/WiSHxS8yu9I/AAAAAAAAHXE/ZJukoNdFjlM--mdO5iMWgNJY0e77i3EIgCLcBGAs/s1600/fire-safety-high-rise-buildings.jpg" style="margin-left: auto; margin-right: auto;" title="Different Performance Levels in Performance Based Design_engineersdaily.com" /></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Fig.1. Different Performance Levels in Performance Based Design</span></td></tr>
</tbody></table>
<br />
The selection of a level from the levels, Immediate Occupancy (IO), Life Safety (LS), Collapse Prevention (CP) is the basis on which the building design. This is mainly a design concept used in earthquake resistant structures.<br />
<br />
Each level has different damage states. In fire-resistant <a href="http://www.engineersdaily.com/2014/03/book-design-and-construction-building-in-value-rickbest.html" target="_blank">design</a>, the life safety level is used, where we expected to have damages to the building with no harm to the life. It can be sometimes chosen between IO and LS also.<br />
<br />
The PBD design will provide more on the provision of hinges in more critical point of the structure making the building more ductile. This ability to provide the performance hinges will describe the ability to have fire dynamics in the spaces of the tall buildings.<br />
<br />
How severe be the fire, the structure should stand still letting all the life to be safe, this must be the output of a PBD design.<br />
<br />
Understanding and studying the fire accidents happened in a modern building will help to assess the critical components that are involved in the fire safety strategy. As this truly reflects the nature of the tall buildings.<br />
<br />
<i>[ Ref: Cowlard[2013], Fire Safety design for tall buildings, Science Direct].</i></div>

Fire and Safety Features of High-Rise Buildings and Structures

Fire and other safety features of high rise buildings and structures is essential. Types and concerns related to these features is discusse...

Use of Lightweight Concrete and Drying Times

Floor and roof systems in reinforced concrete structures

Structural Design Objectives and Philosophy - A Historical Overview

An Overview of Structural Types

Damp proofing of Slabs on Ground

Steel Sheet Piling Works - Workflow Procedure for Site Engineers

Shallow Foundations - An Overview

Selection of Foundation Type

Best Engineering/Scientific/Graphing Calculators

Fire and Safety Features of High-Rise Buildings and Structures

Structures

Civil Engineering

RCC Structural Designing

Transportation Engineering

Spreadsheets

Books