SEAOC Seismology and Structural Standards Committee Update

By Benjamin Mohr, SEAOC Seismology Committee Co-Chair

The SEAOC Seismology Committee has many charges, but fundamentally we’re here to help practicing engineers with seismic design issues. This can include discussing a difficult code interpretation problem, issuing an official position statement, or authoring a code change proposal. Here are a few other tasks we’ve been up to lately:

Review of the SEAOC Structural/Seismic Design Manual (SSDM): Whenever SEAOC updates its highly popular manual, Seismology reviews each problem for “big-picture” issues that could lead designers astray.

ATC-124: Similar to above, SEAOC is teaming up with the Applied Technology Council to create a book of example retrofit problems for ASCE 41. This should help to clarify the many judgment calls that are required to use this document. The Seismology Committee and the Existing Buildings Committee are providing detailed reviews for this effort.

Light-frame structures on podium slabs: This is a very popular building type, but the code is unclear on several important provisions. Our light-frame subcommittee is currently discussing these, and coordinating with other organizations to provide clarity.

In addition, our local-level committees have been hard at work:

The SEAONC Concrete Subcommittee has written a paper on stiffness reduction factors for cracked concrete, comparing different design codes from across the world. The next step for this study is to decide on specific recommendations for designers.

SEAOSD is writing a Blue Book article on performance-based design, which should help the City of San Diego accept performance-based projects more readily in the future.

SEAOCC is writing a Blue Book article on concrete phi factors, taking into account the reduction in ductility that comes with increased axial load.

SEAOSC is writing a design example for retrofit of a nonductile concrete structure. This is in response to a recent ordinance from the City of Los Angeles, requiring evaluation (and, if necessary, seismic upgrade) of 1,500 concrete buildings built before 1977.

The SEAOC Seismology Committee is currently co-chaired by Ben Mohr and Silvia Mazzoni. If you’d like to gain a better understanding of where the building code comes from and where it’s headed, contact Ben (BAMohr@sgh.com) and he will connect you to your local Seismology committee. Getting involved is an excellent networking opportunity, and sharing your knowledge helps all of us design safer structures. 

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