Upgrading the seismic capacity of RC buildings using chevron buckling restrained braces

Abstract

Many RC buildings do not meet the lateral strength requirements of current seismic codes and are vulnerable to significant damage or collapse in the event of future earthquakes. Several systems are available for seismic strengthening of RC buildings such as enlargement of the structural members and adding new structural shear walls.

In. the past few decades, buckling-restrained braces have become popular as a lateral force resisting system because of their capability of improving the strength, the stiffness and the energy absorbing capacity of structures. This study evaluates the seismic upgrading of a 6-story RC building using chevron buckling restrained braces. Seismic evaluation in this study has been carried out by static pushover analysis and time history earthquake analysis. Ten ground motions with different PGA levels are used in the analysis. The mean plus one standard deviation values of the roof-drift ratio, the maximum story drift ratio, the brace ductility factors and the member strain responses are used as the basis for the seismic performance evaluations. The results obtained in this study indicate that strengthening of RC buildings with buckling restrained braces is an efficient technique as it significantly increases the PGA capacity of the RC buildings. The results also indicate the increase in the PGA capacity of the RC building with the increase in the amount of the braces.

The use of BRBs in one bay in each of the perimeter frames of the RC building results in a significant improvement to the base shear capacity of the RC building. In the current study, an increase in the base shear capacity up to150% from the base shear capacity of the original RC building has been achieved by the BRBs.