Comparative Study on Effect of Aspect Ratio on SteelConcentric Braced Frame Structure using Pushover Analysis

The present study focuses on the effect of different aspect ratios i.e. H/B ratio, where H is the total height of the building frame and B is the base width of the building frame, on the seismic performance of the steel frame structures. Here, height of the building is kept constant and the base width is varied. In the present study, seven different aspect ratios ranging from 1.0 to 3.75 have been considered for the ten storey steel frame building with concentric bracing i.e. X bracing and without bracing system. Two types of frames are considered for the study, one with similar steel sections for maximum strength required for beam and column and the other with varying steel sections conforming to the strength and serviceability requirements to withstand the specified loading. For this analytical study, ETABS is used and the comparison between the performances of bare frames with different aspect ratios is made using pushover curves. Roof displacement, base shear carried and performance point are the parameters used to identify the seismic performance of the frames. It is inferred that provision of bracings to the frame structure increased the base shear carrying capacity, performance point and reduced the roof displacement for all types of aspect ratios considered.