Seismic performance evaluation of damage tolerant steel frame with composite steel-UHPC joint

In order to reduce the earthquake damage and improve the resilience of frame structures, a damage tolerant steel frame was proposed in this paper. In this steel frame, the composite Ultra-High Performance Concrete (UHPC) joint and friction damper were applied at the beam to column connection. The UHPC joint can provide excellent crack resistance and deformation capacity, while the friction damper can resist the moment in normal service and dissipate energy under earthquake. To verify the seismic performance of this novel frame, four sophisticated finite element models were built by using ABAQUS, including one conventional moment resisting frame and three novel steel frames with different friction forces. Pushover analysis and nonlinear dynamic analyses were carried out. Compared to conventional frame, both deformation and base shear force of the novel frames were significantly reduced in the simulations. Under maximum considered earthquake (MCE), the conventional steel frame sustained significant yielding in the beam-column connection and column base. While for the novel frames, more than 80% external works were dissipated by the friction dampers, and only slight plastic strain appeared on the composite UHPC joint and column base, demonstrating the realization of the expected damage tolerant performance. Furthermore, the relative small friction force was suggested according to the comparisons between novel frames. The early yielding mechanism caused by the weak friction dampers can effectively improve the energy dissipation performance and damage control.