performance assessment of beam to column moment connection equipped with ellipse pipe steel damper

The high ductile of steel moment-resisting frames (SMRFs) during earthquakes has been challenged due to the brittle fractures of their welded (rigid) beam to column connections. Consequently, SMRFs have suffered severe damages and have produced collapse in main structural members (such as beams and columns). During previous years, energy dissipative devices in connections have been developed by researchers to resolve the ductility problem in rigid beam to column connections of SMRFs. Circular pipe steel damper (CPSD) proposed as a type of steel damper can indicate and dissipate seismic energy mainly through inelastic deformation. Among steel dampers such as shear panel damper, the advantage of CPSD is to resiste applied load in all direction. Under cyclic loading the circular shape of CPSD can change to elliptical shape which causes an extra energy in its absorption capacity. The previous study indicated that the stress concentration was high at both ends in the loading direction. The maximum stress was also observed at lower ends in the direction of loading. Henec, finding the best shape of cross section can enhance the behaviour of pipe steel damper (PSD). In this study, ellipse PSD (EPSD) was proposed for improving rigid beam to column connections of steel structures. For investigating the performance of the proposed EPSD, the behavior of a rigid connection with the common slit steel damper (SSD) SSD was assessed subjected to cyclic load in ABAQUS software. The proposed EPSD has the same weight in comparison with that of the common CPSD. The results of assessment were shown that in the energy dissipation of the proposed EPSD and CPSD subjected to cyclic load is equal to 11.11 kJ and 9.11 kJ, respectively. Thus, the proposed damper in comparison with CPSD can effectively contribute to about 22% of the total dissipated energy. The distribution of stress in the proposed EPSD in comparison with that of CPSD was also uniformly caused in the hight of EPSD. Furthermore, the performance of a rigid beam to column connection equipped with the proposed EPSD and SSD in subjected to cyclic loading was compared. The results revealed that EPSD in the rigid connection increased to about 63% of the total dissipated energy. Due to the distribution of stresses in more area, the strength of the proposed damper increases. Finally, the performance of a rigid beam to column connection equipped with the proposed EPSD and the welded connection in subjected to cyclic loading effectively was compared. The results demonstrated that the connection equipped with the proposed EPSD colud withstand a large number of loading cycles until the failure. Therefore, the proposed EPSD can be used instead of welded connection in SMRFs