8 Dec ANSI/AISC ANSI/AISC s An American National Standard . AISC OCBF. No additional requirements. SCBF. The calculations for this check are exactly the same as those for the AISC check. AISC OCBF. For V and A braces in OCBF the design condition for both minor and major axis is checked as per ,. KL/r ≤ 4 ´ SQRT[E/Fy]. Where.
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All systems now have consistently applied requirements for stability bracing of beams in the SLRS, also based on the level of inelastic behavior in the members. This edition also began the incorporation of system-level capacity design concepts in the development of a new system to be known as eccentrically braced frames EBFs. As findings from these investigations were generated, AISC began to make major changes to the Seismic Provisions document.
The other system, special concentrically braced frame SCBFhas much stricter design requirements for the members, configurations and connections commensurate with the larger ductility demands expected of the system. The requirements for column splices have been significantly increased—again, to avoid the possible consequences of splice failure on the response of the SLRS.
Requirements for both quality control to be provided by the contractor and quality assurance are presented. Column splice requirements for gravity columns have also been included to help provide better overall response of the structural system to seismic demands. The scope of the document has been much better defined, and includes building-like non-building structures.
Many of the design provisions for this system were patterned after those for EBFs. Alsc with all other loading demands, seismic design was rooted in the concepts of allowable stress design of members and their connections. The first, ordinary concentrically 341-5 frames OCBFshave limited requirements consistent with the limited ductility demand expectations resulting 431-05 the small R factor assigned to the system.
These include requirements for strength and deformation of beam-column connections, relative strength of beams, columns and beam panel zones, incorporation of doubler plates and continuity plates.
These anticipated changes should continue the ongoing process of improving structural steel seismic design standards that should result in improved steel construction throughout the United States and other countries throughout the world that adopt this standard.
The overall design of this system is conceptually consistent with that which was in place in the AISC Seismic Provisions. Since composite systems are assemblies of steel and concrete components, ACI forms an important reference document for these systems. Basic requirements for material properties, quality control procedures were also included.
A comprehensive quality assurance plan is now required to demonstrate that the intent of the structural design is met in the construction. Quality control QC and quality assurance QA.
The Uniform Building Code UBC was a major milestone that began the incorporation of system specific requirements for multiple structural steel systems, adding ordinary moment frames and concentrically braced frames. Buckling restrained ais frames BRBFs. Two concentrically braced frame systems have been identified.
Changes in AISC’s Seismic Provisions: AISC 341-05 to AISC 341-10
This system relies on the coordinated efforts of AISC, AWS and ASCE-SEI committees, and the process provides a single point of responsibility for the development of these provisions, thus eliminating duplicative effort—and more importantly, the development of competing documents that would result in minor differences that would undoubtedly result in major confusion in application by practicing engineers. Prior to the Northridge earthquake, the majority of steel wide-flange shapes were either A36 or A Grade All columns in the SLRS must now be checked for maximum forces that ausc be delivered by the system to avoid column overload that could result in severe damage and even collapse of the structural system.
Based on extensive research in both Canada and the U.
The AISC Seismic Provisions were almost completely rewritten inwith additional major modifications in and late The 314-05 Conference, taking place March in Toronto. Two cantilever column systems have also been developed for application in one-story structures. Below is a very brief listing of the intent of the major additions and modifications the AISC that have occurred since the Northridge earthquake.
Structural design drawings and specifications, fabricator shop drawings and erection drawings now have a very 31-05 list of information that is required to be provided to help ensure that the intent of the structural design is completely conveyed and understood by all parties. Wisc more about the conference at www.
Special plate shear walls SPSWs. Both bolted and welded joint fabrication and erection requirements have been increased to better ensure desired performance of SLRS connections. Detailed design and detailing requirements for the web plates, horizontal boundary elements HBEs and vertical boundary elements VBEs and their connections, are all provided.
Many sisc the requirements related to seismic welding are now found in AWS D1. No special requirements for weld filler metals were implemented for seismic design prior to Northridge.
Comparative Seismic Designs of SCBF using AISC and AISC | Bilge Doran –
Work is well underway on the next edition of AISCwhich is planned for publication in Inspection requirements for both visual and non-destructive evaluation NDE inspections of welds are presented in tabular form, based on the recommendations first presented in FEMA This is an entirely 341–05 braced frame system, first introduced inrelying on the design and detailing of steel braces to restrain overall member buckling, thereby significantly increasing the member ductility and overall frame performance.
Eccentrically braced frames EBFs.
This has changed to A steel, partially in response to the Northridge earthquake, since this material provides a specified maximum yield strength and yield to tensile strength ratio. Additional requirements for items like protected zones, demand-critical welds, column splices, etc. System definitions and requirements for ordinary OMFintermediate IMF and special SMF moment frames have been completely overhauled to target aaisc level of expected inelastic demand on the system.
ANSI/AISC 341-05 – Seismic Provisions for Structural Steel Buildings,…
The first edition of these provisions aisd published by AISC inwith a few minor changes incorporated into the edition.
For each system designation, all members of the SLRS have width-to-thickness limitations specified, based on the expected level of inelastic behavior of the member. This is the second system that was also introduced in Modern Steel Construction — March