Pushover Analysis and Incremental Dynamic Analysis of Steel Braced Reinforced Concrete Frames

The recent earthquakes in some part of the world showed the disastrous effect on civilian areas. Most of the existing RC buildings designed only considering gravity loads without seismic design criteria. Therefore, an accurate knowledge is extremely necessary for those buildings that need seismic retrofitting. Steel bracing system can be considered as the most reasonable solution for seismic performance enhancing of RC buildings. The use of steel braces for retrofitting or strengthening seismically deficient RC frame is a reasonable solution for upgrading seismic resistance. Steel bracing is easy to erect, has the flexibility to design for meeting the required stiffness and strength, occupies less space, and economical. This study discusses the seismic behavior of RC buildings strengthened with various types of concentric steel braces, Diagonal-braced, Inverted V-braced, Zipper-braced, and X-braced. The models that have been studied are 3-storey, 6-storey, 9-storey and 12-storey buildings of which are designed by using Etabs. The static pushover analysis and incremental dynamic analysis have been conducted utilizing Seismostruct software to estimate the lateral capacity and compare the results of all the frames and bracing types. It is observed that adding braces upgrade the global capacity of the buildings in terms of lateral load capacity, displacement and stiffness compared to the cases with no bracing, and the X-braced systems performed much better than the other types of bracing. Keywords: Earthquake, Seismic design, Retrofitting, Steel bracing, Pushover analysis, Incremental dynamic analysis.