Study on the Behaviour of the Setback Rc Frame Building Using Pushover Analysis

Abstract

Multi-story framed structures are highly sensitive to the distribution of mass, stiffness, and strength within the horizontal and vertical dimensions of a building, as well as to severe seismic activity. When lateral load-resisting frames in multistory structures have structural flaws, damage usually starts during earthquakes. Furthermore, the structural deterioration brought on by plastification is frequently made worse by these flaws, which might eventually result in total failure. These shortcomings could result from differences in mass, stiffness, or strength between floors. These floor-to-floor variances are often ascribed to sudden changes in the geometry of the frame along its height. In past earthquakes, vertical discontinuities have played a significant role in the collapse of several buildings. It has frequently been observed that abnormal configurations, regardless of plan or height, played a major role in the failures of previous seismic disasters. A setback building is one of the most prevalent vertical geometric anomalies in building designs. It is a structure with a significant drop in its lateral dimension at specific heights. Much research has been done to better understand the behavior of setback and irregular structures and to develop strategies to improve their performance. Pushover analysis is one kind of nonlinear static analysis that is frequently used to assess the seismic response of framed buildings. However, the conventional pushover analysis outlined in FEMA 356:2000 and ATC 40:1996 has limits for regular-shaped buildings. The findings demonstrate that mass-proportional uniform load patterns for pushover analysis and suggested enhancements to the target displacement computation can yield reliable forecasts.