Embedment strength of dowel-type fasteners for the case of cross-laminated timber plane side insertion

Abstract

The strength property of dowel-type connections in cross-laminated timber (CLT) is dependent on the embedment strength of the adopted dowels. In this study, eight groups with 164 CLT cubic specimens were tested based on the half-hole embedment test configuration to address the effects of the potential factors on the embedment strength. In the embedment tests, the axial direction of the smooth dowels was perpendicular to the plane face of the CLT cubic specimens (i.e., in the case of CLT plane side insertion). The considered influencing factors included the loading angle θ, the ratio between the thickness of the transverse layers to the thickness of CLT (RTrLay), and the gap between the longitudinal laminas within the embedment area. The experimental results were further utilized to verify the current empirical equations that could predict the embedment strength. Results show that the embedment strength of the dowels in the case of CLT plane side insertion is enhanced by 19.96–68.40 % when changing the θ from 90 degree to 0 degree. When the gap between the longitudinal laminas exists in the embedment area, the distinction between the embedment strength measured through the θ of 0 degree and that measured through the θ of 90 degree can be weakened. When the θ is 90 degree, the gap existing in the embedment area has almost no effect on the CLT embedment strength. In contrast, when the adopted θ is switched to 0 degree, the gap existing in the embedment area can weaken the CLT embedment strength by up to 37.11 %. When no gap exists in the embedment area, the embedment strength declines with an increase of the RTrLay; whereas when a gap between the longitudinal laminas exists in the embedment area, a growing trend of the embedment strength is illustrated with the increasing RTrLay.