Extension of The Improved Upper-Bound Pushover Analysis For Seismic Assessment of Steel Moment Resisting Frames With Setbacks

Pushover analysis technique is a key tool for the performance-based seismic design that has been largely adopted in the new generation of seismic codes. Therefore, more precise and reliable performance predictions are highly demanded. Improved upper-bound (IUB) pushover analysis is one of the advanced nonlinear static procedures (NSPs) that has been recently developed. This procedure estimates adequately the response of regular and tall buildings. In this study, IUB is extended to assess the seismic response of irregular buildings with setbacks. To this end, an adjustment of the IUB lateral load distribution is implemented by integrating a third mode of vibration to control the response of these complex buildings. Fifteen multi-storey steel frames with different types of setbacks including a reference structure are used to test the accuracy of the proposed procedure by comparing its results to those from other NSPs and the nonlinear time history analysis (NLHA). The findings show the superior capacity of the extended IUB in predicting the seismic response of buildings with different levels and types of setbacks.

Performance Based Seismic Design of Reinforced Concrete Building by Non-Linear Static Analysis

In past two decades earthquake disasters in the world have shown that significant damage occurred even when the buildings were designed as per the conventional earthquake-resistant design philosophy (force-based approach) exposing the inability of the codes to ensure minimum performance of the structures under design earthquake. The performance based seismic design (PBSD), evaluates how the buildings are likely to perform under a design earthquake. As compared to force-based approach, PBSD provides a methodology for assessing the seismic performance of a building, ensuring life safety and minimum economic losses. The non-linear static procedures also known as time history analysis are used to analyze the performance of structure . Plastic hinge formation patterns, plastic rotation, drift ratio and other parameters are selected as performance criterias to define different performance level. In this paper, a five-storey RC building is modelled and designed as per IS 456:2000 and analyzed for lmmediate occupancy performance level in ETABS2015 softwere. Analysis is carried out as per FEMA P58 PART 1 & 2. Plastic hinges as per FEMA273. From the analysis, it is checked that the performance level of the building is as per the assumption