Behaviour of frame structures with concentric diagonal bracings under lateral loading

In this study, nonlinear static analysis was performed to compare the structural response of different type of moment resisting frame buildings with and without concentric diagonal braces (CBs) subjected to lateral loading. For the purpose of this study, moment resisting frame buildings with 4, 8, 12, and 16 stories were taken into consideration. The buildings had the same plan, which included three bays on each direction were selected as a case study. The existing steel frames were designed according to two different cases. They were referred to as a) flexible moment-resisting frames and b) rigid moment-resisting frames. Then, concentric braces were inserted in the middle bay of the existing frames. For the braced frame structures, diagonal type configuration was used. A total of 16 different steel frame structures were under investigation. Capacity curve, total base shear, interstorey drift index, and global damage index were evaluated for each frame system. Depending upon the design properties of the frames, the results exhibited a substantial improvement in the earthquake performance of the frames with the incorporation of diagonal type braces.Keywords: Diagonal brace, Earthquake, Frame, Nonlinear analysis, Structural response