Ground motions that contain velocity pulses may cause greater structural damage than ground motions that do not contain pulses. The effects of pulse-like motions are best approximated in the time domain using nonlinear response history analysis. Current approaches for incorporating pulse effects are not reproducible since they largely rely on engineering judgment and often result in unrealistic representation of the hazard. This study extends a method by Shahi and Baker (2011) that incorporates the effects of pulse-like motions in probabilistic seismic hazard analyses (PSHA). It uses disaggregation information from the PSHA to construct suites of target spectra that are used for matching an appropriate proportion of pulse-like motions with characteristics (pulse amplitude and pulse period) representative of a desired hazard intensity level. The methodology has been successfully employed for several high-profile projects in California that were subjected to a rigorous peer review process, including the Transbay Tower in San Francisco.

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A nonlinear ground response analysis is conducted for the Niigata-ken Chuetsu-oki earthquake recorded at a free-field vertical array near the Kashiwazaki-Kariwa Nuclear Power Plant in Japan. A bidirectional site response analysis is carried out using LS-DYNA which allows user defined stress-strain relationships to dictate soil behavior subjected to dynamic loading. Dynamic soil behavior is characterized using a two-stage hyperbolic backbone curve implemented with modifications to consider the peak strength of soil layers as well as the strain at which the peak strength is fully mobilized. The effects of bidirectional input motions, strain rate, and the shape of the shear modulus degradation curves are investigated, and it is demonstrated that each factor can have a significant influence on the results.

In areas of high seismicity in the United States, the design of many existing tall buildings followed guidelines that do not provide an explicit understanding of performance during major earthquakes. This paper presents an assessment of the seismic performance of existing tall buildings and strategies for increased resilience for a case study city, San Francisco, where an archetype tall building is designed based on an inventory of the existing tall building stock. A 40-story Moment Resisting Frame (MRF) system is selected as a representative tall building. The archetype building is regular in plan and represents the state of design and construction practice from the mid-1970s to the mid-1980s. Non-Linear Response History Analysis (NLRHA) are conducted with ground motions representative of the design earthquake hazard level defined in current building codes, with explicit consideration of near-fault directivity effects. Mean transient interstory drifts and story accelerations under the 10% in 50 year ground motion hazard range from 0.19% to 1.14% and 0.15g to 0.81g respectively. In order to influence decision making, performance is reported as the expected consequences in terms of direct economic losses and downtime. Furthermore, to achieve increased levels of resilience, a number of strategies are proposed

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