NEHRP 2020 Published

The newly available National Hazard Earthquake Reduction Program (NEHRP) Recommended Seismic Provisions for New Buildings and Other Structures: FEMA P-2082-1 and FEMA P-2082-2 provide a wealth of new provisions for the seismic design of bare and concrete-filled steel deck much of it based directly on SDII research.

Specifically, in FEMA P-2082-1 one can find newly recommended seismic design provisions for bare steel deck diaphragms (see sections 12.10 and 14). These new provisions provide seismic force reduction factor, Rs, that can be applied to diaphragms. This reduction factor is a function of the detailing of the bare steel deck and provisions are also provided for special seismic detailing of bare steel deck. These new special seismic detailing provisions provide both prescriptive and performance-based paths for the engineer to handle conventional and unusual/proprietary situations. In addition new provisions for roof diaphragms in rigid wall flexible diaphragm (RWFD) buildings are provided in the NEHRP recommendations. These new RWFD provisions include guidance for the design of steel deck roof diaphragms employing amplified forces near the boundaries and reduced forces in the interior. All of the new bare steel deck-based recommendations were based on work from the SDII team and the documents include ample commentary and references.

FEMA P-2082-2 provides resource papers towards developing new seismic provisions. Notably, here new SDII findings for concrete-filled steel deck are utilized to develop recommendations. Specifically, the Rs diaphragm force reduction factor for concrete-filled steel deck is established by work from the SDII team. Additionally, the SDII team contributed to resource papers on general determination for Rs and for deflection determinations in diaphragm systems. The resource papers provide excellent state of the art summaries in a number of important seismic topics.

Typically NEHRP seismic recommendations are incorporated, often with some changes, in the forthcoming edition of ASCE 7.