Evaluation the hysteresis behavior of steel frames with combined diagonal bracing and slit damper system with finite element method

Abstract

The yielding steel dampers with suitable energy dissipation capacity improve the building's seismic performance and can be easily replaced after an earthquake. In recent years, due to the low ductility of some bracing systems, researchers have sought to provide a solution to increase the efficiency and increase the ductility of such systems. The use of dampers in bracing frames has attracted the attention of researchers. In this thesis, a type of yielding damper called slit damper is used to improve the hysteresis behavior of steel frame with diagonal brace. The 3D modeling was done in ABAQUS software and finite element method and cyclic static loading according to ATC-24 protocol.

The results of the research showed that the steel frame with a combined system of diagonal bracing and slit damper has regular hysteresis behavior and no loss of strength in both tensile and compressive states. The above combined system can increase the compressive and tensile strength of simple steel frames by 73% and 61%, respectively. Although the ultimate strength and energy dissipation of this system is lower than the diagonal brace, it should be noted that the high energy dissipation of the diagonal brace system is caused by the plastic behavior of the brace and its out-of-plane buckling, as well as the formation of plastic joints at the foot of the columns. It can cause danger to the lives of residents. Double diagonal braces have good behavior, but they have lower ultimate strength and energy dissipation than the double system. Based on the results obtained; By increasing the thickness of the damper, the tensile strength, compressive strength and energy dissipation of the structure can be increased by 25, 18 and 17%, respectively, but in this context, an optimal thickness should be chosen because the wrong choice can damage the plastic joints from the damper to the beam joints. And transfer column. Also, the results showed that by increasing the damper links, the tensile and compressive strength of the structure can be increased by 20.3% and 15.7%, respectively.