Influence of Gravity Framing on the Collapse Probability of Steel Buildings with Special Moment Frames

Abstract

This paper presents the influence of gravity framing on the collapse risk of steel frame buildings with perimeter special moment frames (SMFs) designed in Turkey. For this, four- and eight-story buildings have been designed considering the related current specifications and codes. Header end-plate connections are used for the beam-to-column joints of the gravity frame system. A nonlinear analytical model that simulates the hysteretic behavior of header end-plate connections is calibrated with past experimental data. Nonlinear static pushover analysis (NSPA) and nonlinear response history analyses (NRHAs) were implemented for both four-story and eight-story SMFs with and without the gravity framing to quantify their collapse performance and monitor the system-level seismic response of the building through collapse. The advantage of presence of the gravity framing is investigated and differences in structural responses between the models are also examined. When the models were excited by different ground motions, median responses of the detailed models showed an increase in lateral force carrying capacity and a decrease in first-story drift demand, compared to the nonlinear static pushover analyses results. Furthermore, the results demonstrate that gravity frames in a structure profoundly decrease the possibility of collapse.