Variability in Seismic Collapse Probabilities of Solid- and Coupled-Wall Buildings

Abstract

Reinforced concrete walls are a common lateral load–resisting system for buildings. Common wall configurations are solid planar or solid flanged (H, I, T, L, or C-shaped cross sections) and coupled planar or flanged walls. A coupled-wall system comprises two solid walls linked at most floors by coupling beams that typically have length-to-depth ratios ranging from 2 to 4. In low- to midrise buildings, solid walls are expected and designed to form a single plastic hinge at the base of the wall; in mid- to high-rise buildings, a second hinge is expected in the upper half of the buildings. In coupled walls, plastic hinges are expected at the ends of the coupling beams and at the base of the wall. Because coupled walls offer a more distributed plastic mechanism, they are considered to provide superior earthquake performance to solid walls. This study employs nonlinear incremental dynamic analysis with the suite of ground motions from crustal earthquakes and a set of six idealized wall buildings of varying height to test the hypothesis that coupled walls provide reduced earthquake collapse risk over solid walls; to establish the sensitivity of collapse to modeling decisions and model parameters; and to identify design decisions that can reduce earthquake collapse risk.