Earthquake analysis of knee braced reinforced concrete frames

Earthquakes are destructive natural phenomenons that cause shaking of ground and resulting damage in the structures. The steel bracing system, which is economical, easy to erect and occupies less space, can be used to upgrade the reinforced concrete (RC) buildings against earthquakes. In the present study, four different arrangement of knee bracings with single and double knee elements were considered for 2, 4, 6 and 8 story RC frames. For this, the computer program SAP 2000 was used, and the seismic performance of the bare frames and knee braced frames were examined through the nonlinear static (pushover) analysis and nonlinear time history analysis. Capacity curves, base shear ratio, roof displacement, story displacement, and inter-story drift ratio variations were obtained and discussed comparatively for each case. The results showed that knee bracings can be used as an alternative to upgrade seismic resistance of the structure while the total weight on the buildings do not change significantly.