Proposed Modification for ADAS Damper to Eliminate Axial Force and Improve Seismic Performance

Abstract

ABSTRACT A variety of yielding dampers have been proposed with different materials and configurations and constructed for various structures to improve their seismic performance. ADAS dampers are considered as energy dissipation tools to experience uniform yielding according to their specific geometry. However, the damper cannot perform ideally in large deformations due to an unexpected tensile axial force. This axial force not only creates strain localization at the middle of X-shape plates but also with an unexpected increase in the level of damper force can impose damage to main members. This paper proposes a modified ADAS damper with a shape similar to ADAS dampers and boundary conditions similar to TADAS dampers. Given the geometry of the proposed damper, the generated axial force reaches the bracings through side plates instead of triangular plates, improving the operation of the damper. In order to design a suitable damper, an equation is suggested to determine the maximum shear stress by modeling the damper using the Abaqus program and parametric study. Other findings include the evaluation of the monotonic, hysteretic, and seismic performance of this damper. On one hand, the results show that the increase in force level in the nonlinear range is about 30% for MADAS damper, while it exceeds 150% for ADAS dampers. On the other hand, the maximum equivalent plastic strain in ADAS is twice that in the MADAS. In addition, the evaluations of monotonic, cyclic, and dynamic behaviors indicate that MADAS dampers have great energy dissipation in large deformations.