Analytical and experimental investigation on performance of ENTA damper systems for RC moment frame under cyclic loading

An external ENTA damper system or steel frame seismic retrofit approach was investigated for historic reinforced concrete (RC) buildings. RC frame specimens were evaluated under cyclic lateral loading to confirm the external retrofit approach. The investigation involved an examination and comparison of hysteresis-based behaviors, such as strength, ductility, and energy dissipation, with the aim of gaining a deeper comprehension of the distinct impacts of external retrofit systems on seismic performance. The experimental findings indicate that the implementation of the external ENTA damper system and steel frame effectively enhanced the stiffness and durability of vulnerable RC moment frames, while maintaining their deformation capacity. The enhancement of the energy-dissipation capacity was achieved by the use of measures to prevent premature failure of the RC beam-column joints. On the basis of the experimental results, the failure mechanism of the RC frame was discussed, considering the shear connection behavior. In order to further validate the experimental results, analytical modeling of the undamaged specimens was carried out using the LS-DYNA program. The test strengths of the frame specimens were evaluated and compared to the anticipated values derived from a simple plastic mechanism. •The ENTA damper systems increased the load-bearing capacity of the RC frame structures.•ENTA damper systems significantly improved the stiffness resistance and energy absorption of RC frame structures.•The ENTA damper systems prevented serious damage to the beam-column joints in RC frame structures.•The FE model appropriately predicted shear, ductile and behavior concrete failure in RC frame and retrofitted RC frame.