Performance-Based Seismic Design of Steel Buildings Using Rigidities of Connections

This paper develops a performance-based seismic design (PBSD) procedure specifically for steel structures. Several improved steel connections were proposed to eliminate brittle fractures in welds following the Northridge earthquake of 1994. Making connections more flexible was considered to be an attractive option. One type of flexible connection considered in this study is expected to be economical and improve the behavior of steel structures, making them more seismic load-tolerant. However, the partial rigidities of connections need to be considered appropriately. To consider major sources of nonlinearity and rigidities of connections, structures are represented by finite elements. Steel structures are excited by seismic loading applied in the time domain, as required for the most sophisticated analysis. The algorithm incorporates major sources of uncertainty. To implement the PBSD concept, a novel reliability evaluation technique is proposed by integrating the first-order reliability method, the response surface method, and the advanced factorial design concept, producing compounding beneficial effects. The accuracy and efficiency of the procedure are verified with three informative examples. The study confirms the benefits of multiple deterministic analyses, as suggested in recent design guidelines. The behavior of the post-Northridge design is demonstrated to be superior to that of the pre-Northridge design, as expected. The PBSD procedure is appropriately documented for practicing engineers working on structural steel design and construction for everyday use.