Investigation of Coupled Shear Walls Structural Performance Considering the Stiffness Degradation of Connecting Beams

Abstract Shear walls are the most common systems that provide strength and stability against horizontal forces in multi-story buildings. In an arrangement where the walls attached have connecting beams (or coupling beams) amid them, the redistribution of the shears and the control of the displacement become even more efficient. Those beams often tend to suffer damage under strong lateral forces from either wind or seismic loads, in the form of diagonal tension cracks, yielding, and finally the development of a limited plastic hinge. This type of deterioration does not occur instantly but gradually advances over the height of the building, provided there is a story shear distribution. Consequently, this leads to a change in the internal load-bearing path and, thus, to a general loss of the building’s structural integrity. Conventional modelling typically uses plastic hinges at both ends of beams; hence, actual post-yield behaviour is not captured, particularly in deep beams with diagonal reinforcement. After the concrete core deteriorates, inclined rebars may undergo truss action, allowing for continued load transfer even after the rebars yield. A novel proposal model for coupling beams that include two-end plastic hinges and an additional diagonal strut element is incorporated to reflect this behaviour. Finite element simulations with this model are validated with experimental data and analytical degradation models. Results show that stiffness degradation occurs rapidly in the elastic stages. In contrast, diagonal reinforcement provides the much-needed support to continue the load path and maintain system integrity beyond the inelastic range. This model will be convenient for seismic design and nonlinear analysis, enhancing simulation fidelity and proposing necessary engineering actions.