Cross-laminated timber with gaps for wall elements

Cross-laminated timber (CLT) is one of the most relevant modern mass-timber products with continuous growth in worldwide market share. The increased demand of CLT products, however, goes hand in hand with an increasing use of raw material. Among various approaches to optimize the use of timber, the reduction of material within the CLT layup is pursued in the work presented here. The objective is to decrease structural overperformance, which is evident within CLT wall elements where fire resistance is oftentimes the decisive design factor. Toward this aim, an experimental study was performed to examine the effects of CLT layups with gaps on mechanical properties. Tests on bending and buckling behavior as well as in-plane shear properties were performed. A variation of layups with different gap widths and lamination dimensions (75 mm, 95 mm, 115 mm) was investigated. This study shows that bending and buckling properties are strongly influenced by the reduced volume fraction in the layup. Increased shear deformation in the cross layers led to a decrease in load-carrying capacity and element stiffness. This showed signs of premature rolling shear failure. ... mehrThe evaluation of in-plane shear tests showed a much better correlation with the reduced net crossing-area between adjacent layers. Large gaps significantly influence the properties of CLT layups. In this study a material reduction up to 40 % was achieved, while sustaining considerable load-carrying capacity for the use of load-carrying wall elements.