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SUMMARYThis paper describes new concepts for the structural design of high-rise buildings, in which a system is introduced to increase the dependable structural damping by a factor of 5-10. By so doing the dynamic response of the building to wind effects (buffeting and vortex shedding) is virtually eliminated, leading to substantially reduced lateral design forces and assured occupant comfort. Substantial reductions in structural member size and construction cost savings can be realized in many cases. This may signifi cantly improve the economic viability and sustainability of a development. The paper describes some means by which high levels of damping may be achieved and is illustrated by an implementation on a building, currently under construction, subjected to wind and seismic excitation.

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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