UCLA

Strong wind events are the major factor governing the structural design of many tall buildings in regions with low-to-moderate seismic hazard; however, unlike seismic design, where performance-based design of tall buildings has become common in regions impacted by strong shaking, wind design is still based on linear elastic response under ASCE 7 strength-level demands. Application of performance-based wind design, where modest nonlinear responses are allowed in ductile elements at prescribed locations, has been hampered in part by the lack of experimental data on the performance of key elements subjected to wind loading protocols. For tall concrete buildings subjected to strong wind, allowing modest nonlinearity in coupling beams is an attractive option; therefore, four 2/3-scale reinforced concrete coupling beams were tested under a simulated windstorm loading protocol, which consists of a large number of elastic load cycles and a dozen mildly-inelastic displacement cycles. The test parameters included aspect ratio, presence of floor slab, level of detailing (seismic versus standard), and loading protocol (wind versus seismic). The test results indicate that rotational ductility demands of 1.5 can be achieved with only small residual crack widths (less than 1/16 in.; 1.6 mm) and no concrete spalling or bar buckling, indicating that allowing modest inelastic responses in strong wind may be a viable approach.