Displacement Based Intelligent Seismic Assessment of Existing Steel Buildings

Abstract. Performance based seismic design usually requires nonlinear dynamic or static analyses to assess the performance level of the structure under seismic action. To trace the exact performance point of a structure, these analyses should sometimes be repeated several times over. Analysis iterations mainly depend on the initial design and performance of the structure. So, a method that can present an appropriate initial selection with minimum time and e ort would be precious. Such a method would also be very e ective for seismic structural assessment. In this paper, an intelligent system has been created for the estimation of plastic hinge distribution and lateral ductility distribution and, also, for the assessment of existing steel structures, based on a direct displacement based design procedure. The method has been applied to the steel braced frames with concentric bracing systems in low, medium and high rise buildings. The designer can use this knowledge based system to obtain the performance level of existing steel structures, according to proposed seismic code levels. Finally, the intelligent system has been veri ed using nonlinear dynamic analysis. Keywords: Performance assessment; Arti cial intelligence; Back propagation neural network; Nonlinear analysis.