A novel analytical model for axial load and coupling ratio of balloon-type cross-laminated timber coupled shear walls
Mohammad Kamalinejad, Cristiano Loss, Marjan Popovski
Abstract
This study proposes a novel analytical model to calculate the coupling ratio (CR), axial load in the wall piers, and lateral deformation of balloon-type cross-laminated timber coupled shear walls (BCSWs) with a free-rocking system under lateral loads . With ongoing research efforts to enhance energy dissipation and self-centering of the coupling beams and hold-downs, BCSWs with discrete steel link beams have emerged as a promising structural system for mid- to high-rise mass timber buildings. The performance of BCSWs at both the component and system levels primarily depends on the induced axial force in the wall piers, resulting from the cumulative effect of shear forces in the coupling beams under lateral loads . The current analytical methods for calculating axial load in the wall piers and lateral deformation of conventional coupled shear walls (CCSWs) and hybrid coupled shear walls (HCSWs) with fixed bases are no longer applicable to BCSWs with a rocking system. The analytical method proposed in this study addresses this limitation by predicting the mentioned demands for BCSWs in addition to CCSWs and HCSWs. The proposed method is validated through two case studies , demonstrating its effectiveness in calculating the interest demands in CCSWs, HCSWs, and BCSWs under reverse triangular, uniform, and top-concentrated loads. The results indicate that under a concentrated load at the top of the wall, considered a critical loading condition, the proposed method achieves a maximum normalized root mean square error of 7.25% and a normalized mean absolute error of 6.65% for the case study of BCSWs. These remarkable error metrics, obtained by comparing the predicted responses of the proposed method with numerical simulations using SAP2000 and OpenSees finite element software, underscore the method’s accuracy in predicting the demands on BCSWs under lateral loads in elastic range.