Seismic assessment of steel frames braced with Buckling-Restrained Brace by endurance time method

In Endurance Time (ET) method, structures are subjected to gradually intensifying acceleration functions and their performance is judged based on the maximum time duration in which they can satisfy the predefined endurance criteria. In recent years, Buckling-Restrained Braces (BRB)s are employed to improve the seismic performance of buildings.In this paper, some steel frames braced with Buckling-Restrained Brace (BRB) in ordinary type and with reduced yielding segment, for both diagonal and inverted V chevron braces have been analyzed under ET method and their performance has been compared with each other.The endurance time (ET) method is a dynamic push over method used in seismic evaluation of structures. therefore, this method has been examined and investigated in this work. Result shows that The period of free vibration for frames will be decreased by reducing the length of yielding segment and as a result stiffness increases.According to ET method, in the most of frames, base shear increases by reducing the length of yielding segment, and also maximum roof displacement decreases.

Keywords:

Endurance time method , Buckling-Restrained Braces , Reduced yielding segment , Maximum interstory drift ratio , Equivalent time