Title: SP-339-07: Seismic Shear Force Amplification in Concrete Shear Walls for Buildings Under 240’ (73 m) – Performance-Based Seismic Design vs Code-Level Design
Author(s): Tom C. Xia and Doug Lindquist
Publication: Symposium Paper
Appears on pages(s): 105-120
Keywords: reinforced concrete shear walls, seismic shear amplification, performance based seismic design, code level design, overstrength factor
Performance based seismic design (PBSD) has been widely used for tall buildings as a code alternative design method for concrete shear wall structures. However, most PBSD studies are done for buildings taller than 240’ (73 m). Very few studies have been done for buildings shorter than 240’ (73 m) because PBSD is not required for buildings under 240’ (73 m). It is unclear if and how the shear demand increases observed in typical PBSD analysis should be applied to buildings shorter than 240’ (73 m). This study includes two buildings in the Seattle area that are designed per current codes. The study compares the shear demands predicted by the elastic analysis method with the demands predicated by the nonlinear time history analysis used in PBSD method. The intent of this study is to examine the merits of the new Seattle requirement using a factor to amplify the shear demand for buildings designed at code level and for the building height in the range of 160’ (48.8 m) to 240’ (73 m). It also explores the proper factor to be used in ACI 318 to determine the shear wall capacity.