Application Of Performance-based Seismic Design In Steel Frames

Currently, seismic performances of significant structures are evaluated withPerformance-Based Seismic Design method. Theoretically, the acceptance criteria shouldinclude both interstory drifts and component deformations. It is common practice, however,that only interstory drifts are used for performance evaluation. This paper aims to study therelationship between interstory drifts and component deformations, and thus determinewhether it is reasonable only to consider interstory drifts.Briefly, this paper contains following subjects:1. Conclude concepts such as performance levels, earthquake levels and performanceobjectives, which are fundamental to PBSD. Name various descriptive ways of performanceobjectives and focus on quantitative descriptions of performance levels of frame beams andcolumns. This method defines component performance levels according to inelasticdeformations, expressed by multiples of yield deformation. Force versus deformationrelationship and analysis procedures used in FEM modeling are described.2.6FEM models, accounting for various component sections and steel strength, are set up.Sap2000is used for spectrum analyses under frequent earthquake, and Perform-3D is used forelastic time-history and inelastic time-history analyses under severe earthquakes. Base shearforces of the two are compared.3. Inelastic time-history analyses are conducted with four natural earthquake records.Interstory drifts at the time when components reach certain performance levels are recorded,and these are interstory drift limits for that performance level. Discuss various factors thatmay affect drifts and find the significant ones. Summarize interstory drifts limits and comparethem to generally allowed interstory limits, and the conclusions are as following: for IO, it isreasonable to consider only interstory drifts, while for LS and CP, both interstory drifts andcomponent deformations should be evaluated.