Newly released NEHRP Seismic Design Technical Briefs No. 3 & No. 4

The National Earthquake Hazards Reduction Program (NEHRP) has recently released two new technical briefs. These briefs are published by NIST, the National Institute of Standards and Technology, as aids to the efficient transfer of NEHRP and other research into practice, with the goal of reducing the nation�s losses from earthquakes.

NEHRP Seismic Design Technical Brief No. 3, �Seismic Design of Cast-in-Place Concrete Diaphragms, Chords, and Collectors: A Guide for Practicing Engineers,� was authored by Jack P. Moehle (University of California, Berkeley), John D. Hooper (Magnussen Klemencic Associates), Dominic J. Kelly (Simpson Gumpertz & Heger Inc.), and Thomas R. Meyer (Magnussen Klemencic Associates). The review panel included S. K. Ghosh (S. K. Ghosh Associates, Inc.), Rafael Sabelli (Walter P Moore), and Manny Morden (Brandow & Johnston, Inc.).

This Guide was written for practicing structural engineers to assist in their understanding and application of code requirements for the design of cast-in-place concrete diaphragms (either conventionally reinforced or prestressed). However, many of the concepts that are presented apply equally to other diaphragm types. The material is presented in a sequence that practicing engineers have found useful, with general principles presented first, followed by detailed design requirements. The writers of this Guide consulted widely with code writers and practicing engineers to gather a range of good practices applicable to common diaphragm design conditions.

Brief No. 3 can be downloaded at:

NEHRP Seismic Design Technical Brief No. 4, �Nonlinear Structural Analysis For Seismic Design: A Guide for Practicing Engineers,� was authored by Gregory G. Deierlein (Stanford University), Andrei M. Reinhorn (University at Buffalo), and Michael R. Willford (Arup). The review panel included Graham H. Powell (University of California, Berkeley), Finley A. Charney (Virginia Polytechnic Institute and Advanced Structural Concepts, Inc.), and Mason Walters (Forell/Elsesser Engineers, Inc.).

The technical brief is intended to provide a summary of the important considerations to be addressed, based on the current capabilities of nonlinear analysis technologies and how they are being applied in practice. The scope includes both nonlinear static (pushover) and dynamic (response history) analyses, but with the emphasis towards the latter. This guide is intended to be consistent with building codes and standards, however, as the use of nonlinear analysis for design is still evolving, there are many areas where details of the implementation are open to judgment and alternative interpretations. While this technical brief is concerned primarily with buildings, the guidance can generally apply to nonlinear analysis of other types of structures.

Brief No. 4 can be downloaded at:

posted December 01, 2010