Seismic Fragility Equipped with Curve Development of Frames with BRB’s Smart Materials subjected to Mainshock-Aftershock Ground Motion

The frames with Buckling Restrained Braces (BRB’s) are used as a lateral system. The braces often have a limit amount of ductility and dissipated energy in cyclic loading. Therefore, the use of Shape Memory Alloys (SMA’s) in braced frames with regard to the specific properties of these can be an effective improvement in the seismic behaviour of frames. These alloys become known without the need for replacement after an earthquake and the possibility of many deformations and reversal to initial state. Seismic fragility analysis is one of the most important methods in seismic performance-based design that which lead to seismic fragility curves. Fragility curve is a powerful tool for probabilistic vulnerability assessment of structures. In this paper, seismic behavior of frames with BRB’s and the effect of utilizing SMA’s were studied. Then, three 2D-frames with 3, 6 and 9 story were utilized. The OpenSees software used for the nonlinear time history analysis of frames. The BRB’s considered in two cases, with and without SMA’s. For development of fragility curves, 7 strong ground motion accelerograms including main shock-aftershock earthquake records utilized. By defining the three performance levels for Immediate Occupancy (IO), Life Safety (LS) and Collapse Prevention (CP) based on maximum drift and base shear, the values of the probability of exceedance from these thresholds has been calculated. By comparison the achieved curves, it was found that the frames with the SMA often has the range of IO and LS performance, and the probability of occurrence of the CP level is 38% and in the case of the without SMA the CP performance level will have the of 65%. Using a SMA’s in these frames can reduce the cost of restoring and recovering of damaged systems and make the more resilience building system.