Hysteretic model for bending-type frictional steel truss coupling beams

Abstract

As a novel coupling beam for coupled shear wall structures, the bending-type frictional steel truss coupling beam (BFTCB) concentrates the deformation and energy dissipation in friction dampers at the bottom chord, allowing the main body to remain elastic during earthquakes. As the preparatory work for resilient structure design based on the BFTCB, this work concentrates on developing the hysteretic model for BFTCB. Firstly, the BFTCB stiffness-strength decoupling mechanism was introduced, i.e., the shear strength is provided by friction dampers while webs control its initial stiffness. Secondly, a hysteretic model that reflects the BFTCB two-stage sliding characteristic was proposed. The model consists of a trilinear backbone curve and the unloading and reverse loading rules. The model has eight control parameters, of which two core parameters (initial stiffness and limiting shear strength) are derived from the BFTCB stiffness-strength decoupling mechanism, whereas the remaining parameters are obtained by theoretical analysis and empirical calibration. The hysteretic model was then compared with the test curves and demonstrated good accuracy. Finally, a series of FE prototypes of BFTCB with different design stiffnesses and strengths was adopted to verify the hysteretic model. The results showed that the proposed model fitted well with the FE prototypes, indicating its applicability to BFTCB with varying core design parameters. Therefore, the hysteretic model can be adopted for BFTCB to support the resilient shear wall structure design.