Abstract

Structures with flexible seismic resisting systems tend to develop less seismic forces than their stiffer counterparts. While it has been commonly known that taller buildings in general have longer periods that result in a reduced spectral response, the analysis of one-story buildings with large, wide horizontal flexible diaphragms supported by stiff shear walls are now recognized as having a similar response. This building type often referred to as rigid wall – flexible diaphragm (RWFD) is very common in warehousing and big-box retail occupancies. Estimating the diaphragm deflection has become more important recently, not only because diaphragm deflections are more frequently considered for building separations, property line setbacks, and structural integrity, but also because these deflection estimates are sometimes being used to compute building periods for pseudo- lateral design forces, recognizing that the building’s seismic response is often dominated by the diaphragm’s behavior. ASCE 41 and FEMA P-1026 have presented simplified RWFD seismic design and/or analysis methodologies utilizing linear static design procedures, whose accuracy is reliant upon accurate diaphragm stiffness estimates. The building inventory of RWFD buildings in the seismically active United States (U.S.) west coast is dominated by flexible wood structural panel diaphragms. The most commonly used method for computing wood diaphragm deflections has significant misgivings, often overestimating deflections. This can result in very conservative building movement estimates but more importantly unconservative seismic forces from spectral response procedures. This paper will take a critical look at several approaches to compute wood diaphragm deflection and stiffness, including alternative thoughts behind nail-slip and chord contributions. The recommendations in this paper will assist the structural engineer and researcher in minimizing the underestimation of design loading under ASCE 41 and other stiffness based analysis methodologies.

Disciplines

Architectural Engineering

Number of Pages

11

Download

Share

COinS
 

URL: https://digitalcommons.calpoly.edu/aen_fac/164