Structures built with cross laminated timber (CLT) are an attractive alternative to traditional construction materials in terms of environmental performance and habitability, but its structural behavior is not well understood for each timber specie. This work provides a comprehensive study of the structural behavior of radiata pine CLT shear walls, by means of laboratory testing and numerical analysis of hold down connections. The observed test response of connections is replicated by calibrating two hysteretic models on OpenSees, and its fidelity is revised through the analysis of a full scale wall test and simulation. Main outcomes suggest that advanced modelling tools can accurately reproduce the hysteretic behaviour of the connections of timber panels. In terms of connections behaviour, it is observed that hold downs on radiata pine CLT elements reach less load capacity than hold downs on other wood specie, and no significant difference with the parallel to grain capacity of angle brackets connections is noticed. Besides, it is found that radiata pine CLT walls can achieve suitable cyclic loading performance and reach high levels of displacement ductility. Furthermore, the importance of friction on the load capacity of the wall is showed.
A cross-laminated timber (CLT) wall plays a role of resisting shear stress induced by lateral forces as well as resisting vertical load. Due to the press size, CLT panels have a limitation in its size. To minimize the initial investment, some glulam manufactures wanted to make a shear wall element with small-size CLT panels and panel-to-panel...
Unlike other solid wood panel systems, ICLT panels are manufactured without the use of adhesives or fasteners. Wood members are connected with tongue-andgroove joints within a given layer and with dovetail joints across layers. This reduces cost and allows ICLT panels to be disassembled at end of life to be repurposed in the building material supply chain. In addition, ICLT panels provide a means to utilize lumber from trees killed by mountain pine beetle.
Durability is critical for sustainable construction, and avoidance of moisture accumulation in wood structural members is essential for long-term performance. Little work has been done specifically on hygrothermal performance of massive timber construction.
The objective of this research is to identify building envelope design and construction practices for robust hygrothermal performance of ICLT walls in multiple U.S. climates.
A new numerical model able to account for the interaction between tension and shear forces on typical hold-down connections used in CLT structures is proposed and discussed, starting from results of an experimental campaign conducted at University of Bologna. A specifically developed method appropriate to evaluate the main strength and stiffness parameters from the experimental cyclic force-displacement curves is presented, and the corresponding trilinear backbone approximation is defined. Parameters obtained from tri-linear backbone curves were used to define the effect of the tension-shear interaction on the behaviour of hold-down connections, particularly as far as yielding and peak strength and stiffness parameters are concerned. In order to numerically reproduce the behaviour of connections, a coupled zero-length element is developed and presented. The model is implemented in OpenSees and adopted to model single connection element. The model is calibrated referring to experimental results of specimens loaded only in tension. Then the model is validated referring to tests with increasing level of tension-shear interaction. The proposed model is able to reproduce the actual behaviour of hold-down connection with coupled tension-shear forces under monotonic load conditions. Finally, a first proposal for accounting the hysteretic behaviour is presented, and some preliminary results are shown.
The research presented in this paper examines the performance of 3-ply and 5-ply Cross-laminated Timber (CLT) panels connected with Self-tapping Screws (STS). Different conventional joint types (surface spline with STS in shear and half-lap joints with STS in either shear or withdrawal) along with two innovative solutions were evaluated in a total of 198 quasi-static tests. The first novel assembly used STS with double inclination of fasteners in butt joints; the second was a combination of STS in withdrawal and shear in lap joints. The joint performance was evaluated in terms of capacity, stiffness, yield strength, and ductility. The results confirmed that joints with STS in shear exhibited high ductility but low stiffness, whereas joints with STS in withdrawal were found to be stiff but less ductile. Combining the shear and withdrawal action of STS led to high stiffness and high ductility.
Cross-Laminated-Timber (CLT) is increasingly gaining popularity in residential and non-residential applications in North America. To use CLT as lateral load resisting system, individual panels need to be connected. In order to provide in-plane shear connections, CLT panels may be joined with a variety of options including the use of self-tapping-screws (STS) in surface splines and half-lap joints. Alternatively, STS can be installed at an angle to the plane allowing for simple butt joints and avoiding any machining. This study investigated the performance of CLT panel assemblies connected with STS under vertical shear loading. The three aforementioned options were applied to join 3ply and 5-ply CLT panels. A total of 60 mid-scale quasi-static shear tests were performed to determine and compare the connection performance in terms of strength, stiffness, and ductility. It was shown that – depending on the screw layout – either very stiff or very ductile joint performance can be achieved.
The purpose of this study is to develop a high strength leg joint for shear wall made of small size cross laminated timber panel in a simple system. The joint of CLT in which steel plate was inserted in the central slit and fixed by high strength bolt at inside of short steel pipes was proposed. In order to grasp the failure mode and strength of CLT member, material tests on embedment and shear were carried out using small CLT blocks. The test results indicated that there is few reinforce effect by cross bonding of each lamina. It was concluded that the precise estimation of the strength of CLT member is important in order to develop the joint proposed in this paper.
The goal of this study is to determine the shear and tension resistance capacity of a tenon connector made out of beech plywood for the connection of cross laminated timber wall elements. To determine the tensile and shear capacity of the connector according to EN 26 891 , tensile and shear tests were performed on cross laminated timber elements with thicknesses of 100 mm, 150mm and 180 mm which were connected with the pin connector. The sample set consisted of 36 test specimens of which were 18 tensile specimens and 18 shear specimens. For each test series, three tensile and three shear tests with the top layer parallel and perpendicular to the load direction were performed. The test specimens were stored for four weeks in normal climate at 20 ° C and 65% relative humidity before they were tested. The shear and tension capacity shows a substantially linear behaviour by increasing the length of the connector. In the tensile tests a transverse tension failure happened in the transverse layer. In the shear tests a plastic failure of the beech plywood connector happened.