Seismic Applications

This paper outlines a practical design procedure for steel moment frames with fluid viscous dampers. The design procedure is being developed in accordance with International Code Council Evaluation Service (ICC-ES) AC 494, “Acceptance Criteria for Qualification of Building Seismic Performance of Alternative Seismic Force-Resisting Systems.” The new design procedure decouples the design of the moment frames and the damping system to minimize model complexity and design iteration. Notably, the design of the moment frames follows typical moment frame design procedures found in AISC 341 and ASCE/SEI-7 chapter 12, but with reduced strength and drift requirements to account for reduction in the seismic response provided by the damping system.
Through state-of-the-art FEMA P-695 incremental dynamic analysis on a suite of nearly 100 archetype designs, the design procedure is shown to produce steel moment frame designs that meet the seismic collapse safety requirements of FEMA P-695 and ASCE/SEI-7, while also significantly reducing steel tonnage when comparing to traditional steel moment frames.

Soft weak open front (SWOF) buildings often perform poorly in earthquakes. Two examples are buildings with a street facing garage, or commercial facilities with extensive open display windows. The poor performance of SWOF structures can consist of complete loss of use or even total collapse. This paper presents an approach to protecting such structures via the addition of an energy dissipation system (viscous dampers) such that peak inter-story drifts are limited to about 1% under relatively severe seismic events, thus keeping the deformations within the elastic range. With this addition of damping, earthquake survivability of this class of structures increases significantly. A series of seismic analyses are presented herein to demonstrate the potential performance of the damping system. In addition, a variety of damper installation configurations that provide enhanced energy dissipation are discussed.