With the introduction of Cross Laminated Timber (CLT) into North America and gaining popularity it is of interest to the design and code development community to have codified provisions to facilitate the design of CLT structures. This paper addresses the design aspect of CLT panels subjected to combined bending and compressive axial...
The work presented in this report is a continuation of the FPInnovations' research project on determining the performance of the CLT as a structural system under lateral loads. A two storey full-scale model of a CLT house was tested under quasi-static monotonic and cyclic lateral loading in two directions, one direction at a time. In total five tests were performed; one push-over and two cyclic tests were conducted in the longer symmetrical direction (E-W), and two cyclic tests were performed in the shorter asymmetrical direction (N-S). In addition, before and after each test, natural frequencies of the house in both directions were measured. The main objective of the tests was to investigate 3-D system behaviour of the CLT structure subjected to lateral loads. The CLT structure subjected to lateral loads performed according to the design objectives.
Glued-laminated timber arches are widely used in gymnasiums, bridges, and roof trusses. However, studies on their mechanical behaviours and design methods are still insufficient. This paper investigates the in-plane loading capacity of circular glued-laminated timber arches made of Douglas fir. Experiments were conducted on four timber-arch models with different rise-to-span ratios under concentrated loads at mid-span and quarter-point locations. The structural responses, failure modes, and loading capacity of the timber arch specimens were obtained. The results show that the timber arches presented symmetric and antisymmetric deformation under mid-point and quarter-point loading conditions, respectively. The downward shifting of the neutral axis of the cross section was observed under mid-point loading condition, which contributes to higher loading capacity compared to that under quarter-point loading condition. The loading condition significantly affects the ultimate loads and the strain distribution in the cross section. Based on the design formula in current standards for timber structures, an equivalent beam-column method was introduced to estimate the loading capacity of the laminated timber arches under vertical concentrated loads. The moment amplification factor in the formula was compared and discussed, and the value provided in the National Design Specification for Wood Construction was recommended with acceptable accuracy.
High-rise building made of CLT increases significantly its own weight. Therefore, the collapse of the wall bottom is concerned. Main purpose of this study is to verify the effect of the reinforcement with screws for avoiding the collapse of the CLT wall bottom by extreme vertical load. Test pieces of CLT wall bottom were reinforced by screws. As a result, we got better structural result with screw reinforcement than without screw. From these experimental results, the reinforcement of CLT wall bottom using screw at perpendicular angle to the fiber direction is effective in workability because it does not need seat-dig hole.
CLT wall panels having an opening were subjected to horizontal loading and the failure process of CLT around the opening was compared with the simulation by Finite Element Method. Three types of CLT wall panels of 3500mm length and 2700mm height had an opening of 1500mm length and 900mm to 2000mm height at the center of the wall panel. During the racking test of wall panel cracks appeared at the corner of the opening. The wall panel was modelled with three models. One included a single orthotropic plane element calculated from the mechanical properties parallel and perpendicular direction of lamina layout (Model I). Another included two orthotropic plane elements crossed each other and connected at each nodal point based on the mechanical property of lamina composing the panel (Model II). The third model included laminae of 30-by 120mm cross section arranged vertical and horizontal directions (Model III). The simulation by each model predicted comparatively well the initial shear stiffness of CLT wall panels and the initiation of cracks at the corner of opening.
This thesis presents a numerical study of a novel rocking cross-laminated timber (CLT) shear wall system for low- to mid-rise constructions. The system takes advantage of the high in-plane stiffness of CLT coupled with low-yield steel dampers to control the rocking motion of the CLT shear walls during earthquakes. The low-yield steel dampers connected between two rigid CLT wall panels provide the mechanism needed to dissipate the earthquake energy. This concentrates the damage in the dampers, allowing the system to be repaired efficiently after major earthquakes. Numerical models of the CLT shear wall system have been developed using both OpenSees Navigator and ABAQUS software. Models of low-yield steel damper systems were calibrated using available experimental results. With the rigid floor/roof assumption, a simplified OpenSees model of the CLT shear wall system was demonstrated to be effective and reasonably accurate in predicting the response of the system under large excitations. Therefore, it is efficient and reliable to apply the OpenSees model to study the seismic response of CLT shear wall buildings. A case study of a six-storey CLT shear wall building located in Vancouver, Canada was studied; and, detailed parameteric studies were conducted to investigate the influences of the damper type (damper shear strength), number of dampers, damper location, different earthquake records versus target earthquake design response spectrum, and earthquake peak ground acceleration (PGA) on the building response. It was determined that an optimized damper design with comprehensive consideration of these five factors can provide a building with a small roof drift ratio, as well as minor damages on the dampers. Concepts and examples for connection design are also provided.