Experimental investigation and analytical model of cross-laminated timber wall with coupled U-shaped flexural plate connectors

Abstract

The hold-downs and angle brackets are always used for cross-laminated timber (CLT) wall system, owing to its easy installation. However, if the nails or screws used to connect hold-downs and CLT walls generated a certain plastic deformation though the whole CLT wall system did not collapse after small or moderate earthquake, such connectors can not be replaced easily, which lead to the unsafety of the whole CLT structure building. To achieve the requirements of energy dissipation, easy installation and replacement, the coupled U-shaped flexural plate connector (CUFPC) used for CLT wall-to-floor or wall-to-foundation system is proposed herein. The design of CUFPC was presented following concept that the energy dissipation capacity of CLT wall system depends on the deformation of U-shaped flexural plate (UFP). As a result, the UFP with elliptical holes was adopted. Then, five CLT wall specimens, including two types of CLT wall with hold-downs and angle brackets, one type of CLT wall with CUFPC, and two types of CLT wall with CUFPC and angle brackets, were fabricated and tested under cyclic loading. The failure modes and hysteretic behavior of five CLT wall specimens were analyzed. The test results showed that the excellent hysteretic behavior of CUFPC and the damage of CLT walls with CUFPC focused on connectors. To facilitate the application of CUFPC, the stiffness model of CUFPC was proposed. Compared to the results of tests, the corresponding analytical model can conservatively predict the mechanical behavior of CLT wall system. Thus, for CLT wall with CUFPC, 1% and 2.5% were recommended to be used as elastic and plastic inner-story drift ratio, respectively. This study provides an alternative solution in CLT wall system connector design under earthquake.