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Showing posts with label Steel. Show all posts

2:38 PM , , , ,

Definition of Bar bending

It is the method of bending reinforcing steel into shapes which are important for reinforced concrete construction.

Definition of Bar bending schedule (BBS)


Bar bending schedule alias schedule of bars refers to a list of reinforcement bars, a specified RCC work item that is shown in a tabular form for a smooth view. This table sums up all the necessary particulars of bars ranging from diameter, shape of bending, length of each bent and straight portions, angles of bending, total length of each bar, and number of each type of bar. This information can be used for making an estimate of quantities.
Download: Bar Bending Schedule of a Box Culvert
It includes all the details essential for fabrication of steel like bar mark, bar type and size, number of units, length of a bar, shape code, distance between stirrups (column, plinth, beam) etc.

While generating bar schedules, it is important to take proper care about length. In case of bending, bar length will be raised at the bending positions.

Benefits of the Bar Schedule:


When bar bending schedule is applied along with reinforcement detailed drawing, it makes the quality of construction superior.

Once bar bending schedule is prepared, cutting and bending of reinforcement is performed at factory and shipped to job site. This improves quick implementation at site and minimizes construction time and cost as fewer workers are needed for bar bending. Bar bending also circumvents the wastage of steel reinforcement (5 to 10%) and thus project cost is saved significantly.

It offers the perfect estimation of reinforcement steel requirement for all the structural members which are applied to workout complete reinforcement requirement for whole project.

Bar bending schedule offers the steel quantity requirement in a better way and thus delivers an option to make optimal use of the design in case of cost overflow.

The process becomes simple for site engineers to validate and approve the bar bending and cutting length throughout inspection prior to positioning of concrete with the support of bar bending schedule and thus facilitates in superior quality control.

It becomes easier to handle the reinforcement stock necessary for identified time duration.

It will facilitate the fabrication of R/F with structure.


P.S: Please share this article on social media and elsewhere if you find it useful and do leave your feedback in the comments section below.
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8:40 PM , ,
Magazine: Modern Steel Construction - November 2017

Modern Steel Construction is the official publication of the American Institute of Steel Construction, Inc. MSC brings its readership in-depth information on the newest and most advanced uses of structural steel in buildings and bridges by focusing on innovative and cost-effective steel designs and the products that help bring them to life. MSC is directed exclusively to professionals in the construction industry who make and influence purchasing decisions—whether they are engineers, architects, building owners, contractors, fabricators, retailers or erectors. MSC is the only magazine in the United States devoted exclusively to the design and construction of steel-framed structures.

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2:00 PM , ,
The term corrosion is defined as an act or process of gradual wearing away of a metal due to chemical or electro-chemical reaction by its surroundings such that the metal is converted into an oxide, salt or some other compound. A substance known as rust results from such a process. In other words, the corrosion indicates the deterioration and loss of material due to chemical attack.

What Causes Corrosion of Steel in Concrete?

How to Prevent Corrosion of Steel in Concrete
Concrete provides an ideal protective environment to steel from corrosion. Due to high initial alkalinity, an extremely thin passive film of ferric-oxide (Fe2O3) is automatically formed on the surface of steel. This layer, though extremely thin, effectively protects the steel from corrosion. But unfortunately this layer is effective as long as the surrounding remain alkaline. Therefore, if we can manage to keep the environment alkaline, the corrosion of steel can effectively be prevented and the durability of the structure can be ensured. The alkaline medium can be maintained for a longer period by making the concrete impermeable.
Corrosion is a electro-chemical process in which one part of steel becomes anode and the other cathode. Fortunately, anode reaction can’t start till the passive ferric-oxide film is destroyed by acidic medium or it is made permeable by the action of chloride ions. Similarly the cathode reaction can’t start till sufficient supply of oxygen and water is available at the surface of steel. It can, therefore, be concluded that corrosion of steel can be prevented if the concrete is sufficiently impermeable so as to keep air, water and other such agents out of its reach.

How to Prevent Corrosion of Steel in Concrete?

The steel is the most liable to the corrosion and hence the study of steel corrosion is of paramount importance. To minimize the chances of development of corrosion of steel in concrete, the following preventive measures may be taken.
  1. Avoiding heavily congested reinforcement especially at the intersection of beams and columns.
  2. Avoiding the steel to come into contact with bricks, soil, wood and other porous non-alkaline materials
  3. Avoiding the use of materials which accelerate the process of corrosion i.e. aggregates with high salt contents, water containing salts, etc.
  4. Cleaning the reinforcement with wire-brush to remove the rust scales before placing of concrete
  5. Maintaining a high degree of workmanship
  6. Proper structural design with due provision of cover
  7. Providing cathodic protection to the reinforcement by some suitable method
  8. Providing surface coatings with paints, tars, asphalts, etc
  9. Use of high quality and impermeable concrete
  10. Using stone pebbles in place of badly made cover blocks
  11. Using the correct water-cement ratio
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8:38 AM , , , , ,
"REBARS" is a spreadsheet program written in MS-Excel for the purpose of determining reinforcing bar development and splice lengths. 
"REBARS" is a spreadsheet program written in MS-Excel for the purpose of determining reinforcing bar development and splice lengths.
Specifically, the development lengths and splice lengths for straight bars in tension as well as compression are determined. Also, the development length for standard hook bars is determined. The provisions for development and splice lengths are included for high seismic risk applications per ACI 318-05, Chapter 21. There is also a worksheet which contains reinforcing bar data tables. This version is based on the ACI 318-05 Code.

Program Assumptions and Limitations:

1. This program follows the procedures and guidelines of the ACI 318-05 Building Code, Chapters 12 and 21.
2. The "Calc Development" worksheet, for a given reinforcing bar size, determines the straight development and  splice lengths for a "top" bar and an "other" bar in tension, the straight development and splice lengths for the  bar in compression, and the tension development length of the bar as a standard hook, all at one time.  A complete table of reinforcing bar development and splice lengths is also created for #3 through #18 bars.
3. The "Rebar Data" worksheet contains tables of reinforcing bar data which include various bar properties,  reinforcing bar areas based on spacing, tension development and splice lengths for straight bars, tension  development lengths for 90 degree standard hooks, tension lap splice criteria, compression development  and splice lengths for straight bars, maximum spacing for column ties, and various plain welded wire fabric  properties.
4. This program contains numerous “comment boxes” which contain a wide variety of information including  explanations of input or output items, equations used, data tables, etc. (Note: presence of a “comment box”  is denoted by a “red triangle” in the upper right-hand corner of a cell. Merely move the mouse pointer to the  desired cell to view the contents of that particular "comment box".)
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6:00 AM , , , ,
In order to remain competitive, steelwork contractors have turned to new technologies in order to minimize their costs and meet the tighter deadlines which are being imposed by clients. To a very large extent the technological developments associated with computer aided detailing have played a major part in bringing profound improvements across  the industry. The art of steelwork detailing continues to play a pivotal role in the successful creation of any steel structure. New methods and procedures have given rise to a  process which is now highly integrated and dependent upon both upstream and downstream activities.
Book: Steel Detailer's Manual 2nd Edition by Alan Hayward, Frank Weare

Codes of practice and engineering standards are constantly changing in the construction industry. Many British standards are now being superseded by European EN standards, but many are still in the transition stage. The manual attempts to clarify the present situation. It is however recognized that this is a constantly changing target, and the reader is advised to consult British Standards or any other recognized professional  steelwork organization to deter- mine the latest information. lt is to be hoped that future editions of the manual will contain lists of more firmly established relevant European standards.

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4:19 PM , , ,
Spreadsheet: Steel Beam & Column Analysis as per AISC (ASD) 9th Edition Code
"BEAMCOL9" is a spreadsheet program written in MS-Excel for the purpose of analysis and code checking of  steel beams and columns. Specifically, beams and columns are analyzed / code checked per the AISC 9th  Edition Allowable Stress Design (ASD) Manual. Both actual and allowable stresses are computed, with the final result being a computed "stress ratio" of actual stress/allowable stress. Also, a list of the lightest weight members which satisfy the code check is displayed for convenience.
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4:01 PM , , , ,
Analysis of Single Span and Continuous Steel Beams as per AISC(ASD) 9th Edition Code
"BEAMANAL" is a spreadsheet program written in MS-Excel for the purpose of analysis of either single-span or continuous-span beams subjected to virtually any type of loading configuration. Four (4) types of single-span beams and two (2) through (5) span, continuous-span beams, considered. Specifically, beam end reactions as well as the maximum moments and deflections are calculated. Plots of both the shear and moment diagrams are produced, as well as a tabulation of the shear, moment, slope, and deflection for the beam or each individual span. Also, for steel single-span beams an AISC 9th Edition (ASD) Code check can be performed for X-axis bending and shear.
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11:05 AM , , , , ,

American Institute of Steel Construction(AISC) Search Utility

The new AISC Search Utility for Structural Steel shapes allows users to search shape properties for beams appearing in numerous past AISC publications from 1873 – 2001.The information presented in this publication has been prepared in accordance with recognized engineering principles and is for general information only. While it is believed to be accurate, this information should not be used or relied upon for any specific application without competent professional examination and verification of its accuracy, suitablility, and applicability by a licensed professional engineer, designer, or architect. The publication of the material contained herein is not intended as a representation or warranty on the part of the American Institute of Steel Construction or of any other person named herein, that this information is suitable for any general or particular use or of freedom from infringement of any patent or patents. Anyone making use of this information assumes all liability arising from such use.
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11:52 AM , , , ,

American Institute of Steel Construction Design Examples (Version 13)

The AISC Design Examples provides examples on the application of the 2005 AISC Specification for Structural
Steel Buildings (ANSI/AISC 360-05) and the AISC Steel Construction Manual, 13th Edition. The examples found herein illustrate how the Specification and Manual can be used to determine solutions to common engineering problems efficiently, and outline the background to many of the tabulated values found in the Manual.
It includes examples on design of members for tension,compression,flexure,shear,torsion and combined forces,design of connections,bracing and much more.
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5:06 PM ,
The following is a list of minimum information design documents should include. Design professionals and their staff should use this list to double-check the completeness of their design documents. In addition, all must recognize that the engineer of record is fully responsible for the design and adequacy of all connections.
  • Complete base plate and anchor rod requirements including base plate elevations for all columns, type of leveling system for all columns: material grade, diameter, embedment, hole pattern and size of holes, plate orientation, weld requirements. (Suggest standardization of base plate and anchor rod sizes and use of square bolting patterns.)
  • Bracing gusset plates should not interfere with anchor bolts.
  • Provide sizes and material grade of all members, beams, columns, and bolts, etc. Simplicity and repetition result in cost savings. Standardize the use of A992 steel for mill orders. Specify, not infer, special requirements such as fracture critical material, charpy V-notch testing, etc., on all required members and pieces.
  • Verify orientation of columns on each plan.
  • Provide specific column, truss, and girder splice details and location.
  • Dimensions locating structural steel should be shown clearly on all plans; checked for accuracy, especially principal controlling dimensions and geometry.
  • The structure's geometry should close.
  • The structural drawings should be coordinated with architectural and mechanical requirements.
  • The design should promote repetition of members.
  • All structural items should be clearly located and identified on confirmed structural documents. No reference should be made to other drawings.
  • The specifications should be customized to this project. They should be in agreement with the drawings.
  • Provide clear direction as to the use or prohibition of design drawings or CAD files for member placement drawings.
  • It is recommended that the specifications include a requirement to use pre-qualified fabricators and pre-qualified steel detailing professionals.
  • All connections: Specify whether design is based on ASD or LRFD.
  • Simple shear connections: Always show end reactions (composite or noncomposite). Special connection types, and axial or torsional loads, if any to be fully developed.
  • Provide fully developed bracing connections: Show axial loads (+or -) and whether or not one-third increases in stresses are permissible.
  • Provide fully developed moment connections: Show shear and moments (ft-kips), axial loads, all reinforcement of main members (or at least, clear and complete connection and joint reinforcement requirements) and whether or not one-third increases in stresses are permissible.
  • Provide fully developed truss connections: Shears, moments, and axial loads depending on function of truss.
  • The camber information should be complete.
  • Ensure the feasibility of member erectability.
  • Treat roof and floor opening frames as separate entities to be designed, detailed, fabricated, and erected as freestanding items.
  • Clearly indicate location, type, and limits of fireproofed members.
  • Special cleaning, fireproofing, and painting systems (type, color, exposed, etc.) and locations should be clearly located and identified on design drawings.
  • Clearly specify special safety and/or erection aids or codes in effect.
CONCLUSION
We sincerely hope this document has provided you a greater understanding of those items detailers find necessary for the efficient prosecution of steel structures. We trust that you have gained a better understanding of the positive contribution Engineersdaily and the detailing community can make once given more clearly defined information. To that end, we believe we have provided a guide beneficial to the successful completion of structural steel projects.
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3:44 PM ,
Steel Detailer Civil Engineering
When design documents are incomplete, steel detail drawings cannot be completed and the orderly production of detail drawings is interrupted. Due to their exacting nature, shop detail drawings must be prepared with a performance criteria that endeavors to meet a “zero-defects” standard. This standard produces speed and economy in the fabrication process and in the erection process. The state of the design documents issued for construction today frequently does not meet the “zero-defects” criteria necessary to the detailer and other suppliers. To correct this situation and construct a "paper trail" of information, it becomes necessary to use formal Requests for Information (RFI). The RFI may also be known as ECM (Engineering Clarification Memo) or DEO (Documentation of Errors and Omissions). Whatever form one chooses to use, the intent is the same; a question is asked due to missingnd/or ambiguous information on the design documents, and an answer is needed to clarify the missing and/or ambiguous information. Unfortunately, the RFI/ECM often becomes misused as a tool for the completion of design documents, rather than an instrument for clarification of completed design drawings.

The detailer, in an effort to meet project schedules, must make a thorough search of the design documents for information. During the bidding stage, it is extremely difficult to identify those items that result in inadequate design drawings, requiring the detailer to factor in the time and cost of any deficiencies. Such problems are found during the meticulous procedure of detailing, which often occurs long after award of prime contracts. First, the detailer must identify the problem. Next, the detailer must analyze the problem in order to ask an intelligent question. 
Additional manpower or supervision may be required to confirm the action of the individual discovering the problem, before the question may be forwarded. It may be necessary for sketches or supplemental drawings to be produced to illustrate the problem. Once an RFI is submitted, it means the detailer has exhausted all available resources and has a legitimate question. The exacting nature of detailing requires exact information. To make this process effective, 100% effort is required of all on the construction team to research and answer the question -- not only promptly, but also completely. The frequency of their development can easily make the hours for the detailing process multiply by 2, 4, or more times the normal amount, which may result in delays in the ordering of material and in the delivery of shop drawings. The outcome is additional compensation owed to the detailer, especially if the delay requires the detailer to demobilize, reassign, and remobilize personnel. There is obviously a potential impact to the fabricator's, the erector's, and the owner's schedules and profits as well.

Therefore, with regard to inadequate design drawings,the detailing community should take these positions:

1. It is the responsibility of the owner to allow the design professional both adequate time and financial resources to prepare a complete set of design documents.
2. It is the responsibility of the design professional to provide the owner with complete and accurate design documents that give thorough information (per AISC Code of Standard Practice) that allows the detailer to correctly interpret the design intent and to produce quality drawings.
3. It is the responsibility of the Detailer to inform the fabricator (client) of the inadequacies of the design documents during the shop drawing process and the detailing cost and schedule impact of those inadequacies.
4. It is the responsibility of the fabricator (client) to inform the contractor/owner of those same inadequacies and the resulting cost and schedule impact. (Please note: Staff hours, which are misutilized or must be reassigned, result in extra costs. Extra charges may result without the addition of drawings or material.)
5. It is the detailer’s responsibility to produce shop drawings, not to check or coordinate contract documents. Should the client desire the detailer to perform such an activity or to prepare Engineering Clarification Memos
(RFI), such activities shall be considered as extra work for which the detailer is entitled to compensation. Unless otherwise agreed to, the detailer’s right to be paid is not contingent upon the client being reimbursed.

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3:25 PM ,
The design document is the medium by which the architect/engineer communicates to the steel detailer (and other trades) the locations, sizes, stresses, and other requirements of every piece of steel in the project. If any of the information is missing, incomplete, or erroneous, the steel detailer has been spoken to in incomplete sentences. The detailer will then misunderstand the intent, misinterpret the meaning, or be unsure how to proceed. Communication is the key to all we do. To do their job, steel detailers require complete, checked, coordinated, design drawings, especially principal controlling dimensions and geometry. We rely on the designers to develop plans, sections, views, and details, which fully describe and illustrate the desired end product. Designers must assist the detailer as much as possible in connection development and should design moment, special, and heavy connections on the design drawings. If the fabricator or erector elect to make a change to the designed connection, they will have a frame of reference to discuss this with the engineer. It must be remembered that steel detailers produce shop drawings; this is the service they are trained for, and this is what they are paid for. Most steel detailers do not have the time, the financial resources, the legal authority, or the insurance to check or to complete design drawings or to do connection design. Steel detailers are totally dependent on the design team to communicate to them the data required to permit the successful completion of the project.
 
Just as architects and engineers use design documents to communicate with the steel detailer, the shop drawings and the approval process are methods the detailer uses to communicate with the reviewing agency or the engineer of record. Shop drawings must be checked to assure that all project requirements, codes, and specifications have been met. If the detailer fails to provide all the necessary information, the designers will be delayed and may require resubmittal of the drawings -- a delay and added expense to all parties involved, including the project owner.
 
The AISC Code of Standard Practice addresses the design requirements on the part of the engineering profession. Adherence to this code is a first step in successful communication with the Steel Detailer. Additionally, the NISD Steel In Schedule Driven Projects are excellent sources of reference for detailers and Industry Standard publication and the AISC publication Working With Structural designers alike.
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3:19 PM ,
Steel Detailer
Steel detailing is the preparation of shop fabrication drawings from structural and architectural design documents. The detailer is the interpreter of the engineering design, translating the designer's intent into the language of the steel fabrication industry. This interpretation involves the analysis, evaluation, organization, and communication of the structural design. Each and every part of the steel fabricator’s scope of work is defined, from every bolt, weld, and dimension, to the assignment of an identifying mark for each component to facilitate member placement. Although some steel fabricators maintain an in-house detailing office, it is common practice for fabricators to rely on the services of qualified independent detailing firms.

From Design Documents to Steel Details
The analogy of a steel detailer as an interpreter has been used to describe their function in the steel construction industry. It is the detailer who takes the information from the design documents, develops the mill orders and fabrication drawings, and provides other required supporting services. This information must be presented in a format that is required by the fabrication facility and members of the construction team. It may be said that the structural design documents are really a message to the detailer. The clarity of that message dictates the ability of the detailer to correctly interpret and provide the design information. When the architect and engineer have completed their design of a steel frame structure, it is time for the structure to be produced. Typically, at the onset of a project, the steel detailer is the first subcontractor to begin using the design documents and one of the first to determine if the designs are complete and accurate. The process used by the steel detailer is just as it is for making any other product. All of the component parts of the structure are gathered together into an organized system (Member Placement Plans) to be used by all detailers involved in the project. This includes individuals doing column details, beam details, braced frame details, girder details, horizontal and vertical bracing details, and many others, depending on the project at hand.

The most important concept to understand about the process is that steel detailing is a production line type of operation. When a steel detailer produces drawings, it is essential to have all of the information required for the assembly of the structure. When even one component is missing, it can have a serious impact on the detailer's production of shop drawings. Keep in mind that there is a great difference between the creative process of making design drawings and the production process of making steel detail drawings.
  
When the design drawings are found to be incomplete or inaccurate, the detailing production process cannot run smoothly. Production becomes inefficient and fragmented. The once smooth-running production line has to stop, back up, and start again, and thus results in a lot of extra time in detail drawing production. This list illustrates those significant elements of the design documents used by the detailer to furnish the required detailing services.

From Design Documents
  • All structural design documents.
  • Foundation plan, column schedule, and associated sections.
  • Structural framing plans and sections.
  • General notes and project specifications.
To Steel Details
  • Complete shop detail and member placement drawings.Material procurement lists.
  • Anchor rod plans and embedded material plans as well as shop details of embedded items.
  • Member placement plans and sections.
  • Job standards, painting requirements, special notes, material & weld requirements, bolting information, etc.
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