Withdrawal Properties of Self-Tapping Screws in Japanese larch (Larix kaempferi (Lamb.) Carr.) Cross Laminated Timber

Junhua Xu,Haiqing Ren,Guofang Wu,Yingchun Gong,Shuangbao Zhang

doi:10.3390/f12050524

Abstract

With the increasing popularity of cross-laminated timber (CLT) constructions around the world, there have been attempts to produce CLT using local wood species in different countries, such as Japanese larch (Larix kaempferi (Lamb.) Carr.) in China. Thus, the need to investigate the connection performance also increases to support the design and construction of CLT buildings using local wood species. In this study, the withdrawal properties of three different types of self-tapping screws (STS), with a diameter of 6 mm, 8 mm, and 11 mm, were tested with Japanese larch CLT. The results revealed that the withdrawal strength of STS increased with increasing density and effective length, but decreased with an increasing diameter. With a density increment of 0.05 g/cm3, the withdrawal strength increased by an average of 9.4%. With an effective length increment of 24 mm, the withdrawal strength increased by an average of 1.4%. An empirical regression model was adopted to predict the withdrawal strength of Japanese larch CLT based on the results, which can be used for potential engineering design of CLT connections using STS.

Highlights

Cross-laminated timber (CLT) is a planar, large-dimension engineered timber panel, which has been used for load-bearing components including wall, floor, and roof elements in single- and multistory buildings, halls, and bridges around the world, especially in Europe, Canada, and America [1,2,3,4,5]
Fasteners and connection solutions commonly used in traditional timber structures, like dowels, bolts, nails, wood screws, angle brackets, and hold-downs, can be used in CLT structures
Various fasteners and connection solutions are compatible with CLT constructions, and most of them are based on single-dowel type fasteners

Summary

Introduction

Cross-laminated timber (CLT) is a planar, large-dimension engineered timber panel, which has been used for load-bearing components including wall, floor, and roof elements in single- and multistory buildings, halls, and bridges around the world, especially in Europe, Canada, and America [1,2,3,4,5]. Existing knowledge concerning linear timber products has been widely used for connecting CLT elements. Fasteners and connection solutions commonly used in traditional timber structures, like dowels, bolts, nails, wood screws, angle brackets, and hold-downs, can be used in CLT structures. CLT requires additional attention and, new specialized connection solutions and systems, such as self-drilling smooth dowels, self-tapping screws, tight-fitting bolts, inner metal plates [7], the X-RAD connector system [8,9], the SHERPA CLT connector [10], and embedded steel tubes in combination with glued- or screwed- in steel rods [11,12,13,14], have been invented. Various fasteners and connection solutions are compatible with CLT constructions, and most of them are based on single-dowel type fasteners.

Objectives

Methods

Results

Conclusion