Improving the behavior of concentrically braced frame braces using a flexural damper: Experimental and numerical study

Although the concentrically braced frames (CBFs) systems have high lateral elastic stiffness and strength, they reflect a low seismic energy absorption capacity mainly due to their diagonal buckling under compressive loading. To overcome this problem, researchers have proposed metallic shear damper as the most popular due to its satisfactory performance and affordable cost. In this paper, an innovative metallic damper with a flexural mechanism is proposed to improve the behavior of CBF systems. It provides ease of fabrication and replacement after damage, competitive cost, and improved resistance to buckling of the CBF member. The performance of the damper was evaluated experimentally and numerically. Subsequently, two types of dampers, (a) made of rectangular flexural plates (RFP) and (b) made of I-shaped flexural plates (IFP), were designed and evaluated. Experimental as well as numerical results indicated that both dampers provide stable and symmetrical hysteresis curves with a high energy absorption capacity. Results indicated that the IFP damper has greater stiffness (1.94-2.3 times) and ultimate strength (1.76 times) but a lower overstrength (66% less) and ductility (47% less) than the RFP damper. Moreover, design expressions were presented for the proposed damper and showed a good agreement with finite element results.