Long-Period Building Response to Earthquakes in the San Francisco Bay Area

Abstract

This article reports a study of modeled, long-period building responses to ground-motion simulations of earthquakes in the San Francisco Bay Area. The earthquakes include the 1989 magnitude 6.9 Loma Prieta earthquake, a magnitude 7.8 simulation of the 1906 San Francisco earthquake, and two hypothetical magnitude 7.8 northern San Andreas fault earthquakes with hypocenters north and south of San Francisco. We use the simulated ground motions to excite nonlinear models of 20-story, steel, welded moment-resisting frame (MRF) buildings. We consider MRF buildings designed with two different strengths and modeled with either ductile or brittle welds. Using peak interstory drift ratio (IDR) as a performance measure, the stiffer, higher strength building models outperform the equivalent more flexible, lower strength designs. The hypothetical magnitude 7.8 earthquake with hypocenter north of San Francisco produces the most severe ground motions. In this simulation, the responses of the more flexible, lower strength building model with brittle welds exceed an IDR of 2.5% (that is, threaten life safety) on 54% of the urban area, compared to 4.6% of the urban area for the stiffer, higher strength building with ductile welds. We also use the simulated ground motions to predict the maximum isolator displacement of base-isolated buildings with linear, single-degree-of-freedom (SDOF) models. For two existing 3-sec isolator systems near San Francisco, the design maximum displacement is 0.5 m, and our simulations predict isolator displacements for this type of system in excess of 0.5 m in many urban areas. This article demonstrates that a large, 1906-like earthquake could cause significant damage to long-period buildings in the San Francisco Bay Area.

Sensitivity of the Earthquake Response of Tall Steel Moment Frame Buildings to Ground Motion Features

“…The spectral acceleration level at which structural response becomes unbounded is the collapse capacity of the building. Finally, the emergence of rupture-to-rafters simulations [24] has led to extensive investigations on the performance of tall steel moment frame buildings under large simulated earthquakes in Los Angeles, San Francisco, and Seattle (e.g., [21,30,43,29]). …”

Effects of Isolation Period Difference and Beam-Column Stiffness Ratio on the Dynamic Response of Reinforced Concrete Buildings

“…For example, Ariga et al (2006) studied the resonant behavior of base-isolated high-rise buildings in terms of longterm ground motion, and Olsen et al (2008) also investigated long-term building responses. Deb (2004), Dicleli and Buddaram (2007), Casciati and Hamdaoui (2008), Di Egidio and Contento (2010) also have made progress in the study of isolated building systems.…”

Efficient Design in Building Construction With Rubber Bearing in Medium Risk Seismicity: Case Study and Assessment

“…Base isolator with hardening behaviour under increasing loading has been developed for medium-rise buildings and sites with moderate earthquake risk (Pocanschi, Phocas 2007). Resonant behaviour of base-isolated high-rise buildings under long-period ground motions was dealt with by Ariga et al (2006) and for long period building responses by Olsen et al (2008). Wilkinson and Hiley (2006) presented a non-linear response history model for the seismic analysis of high-rise framed buildings.…”