Wood-frame is the most common construction type for residential buildings in North America. However, there is a limit to the height of the building using a traditional wood-frame structure. Cross-laminated timber (CLT) provides possible solutions to mid-...
Cross-laminated timber (CLT) products are gaining popularity in the North American market and are being used in midrise wood buildings, in particular, in shearwall applications. Shearwalls provide resistance to lateral loads such as wind and earthquake loads, and therefore it is important to gain a better understanding of the behavior of CLT shearwall systems during earthquake events. This paper is focused on the seismic performance of connections between CLT shearwall panels and the foundation. CLT panels are very stiff and energy dissipation is accomplished by the connections. A literature review on previous research work related to damage prediction and assessment for wood frame structures was performed. Furthermore, a test program was conducted to investigate the performance of CLT connections subjected to simulated earthquake loads. Two different brackets in combination with five types of fasteners were tested under monotonic and cyclic loading protocols. In total, 98 connection tests were conducted and the monotonic load-displacement curves and hysteretic loops were obtained. In this paper, an energy-based cumulative damage assessment model was calibrated with the CLT connection test data. Finally, a correlation between the damage index and physical damage is provided.
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. As currently there are no standardized methods for determining the resistance of CLT shearwalls under lateral loads, the design approaches are left at the descretion of the designers. The most common approach that is currently used in Europe and North America assumes that the resistance of CLT walls is a simple summary of the shear resistance of all connectors at the bottom of the wall. In this report some new analytical models for predicting the design (factored) resistance of CLT walls under lateral loads were developed based on connection properties. These new models were then evaluated for their consistency along with their models that are currently used in North America and in Europe.
This paper presents results of an experimental study of commonly used angle bracket and hold-down connections in Cross Laminated Timber (CLT) wall systems under bi-directional loading. Monotonic and cyclic tests of the connections were carried out in one direction, while different levels of constant force were simultaneously applied in a perpendicular direction. The experiment aims to consider the combined and coupling effect of loads for connections in a rocking CLT shear wall system. Key mechanical characteristics of those connections were calculated, evaluated and discussed. The results show that shear and tension actions for hold-downs are quite independent but strongly coupled for angle brackets. The study gives a better understanding of hysteretic behaviour of CLT connections, and provides reliable data for future numerical analysis of CLT structures.
The objective of this research is to develop a model to predict the distribution of loads within connections with multiple self-tapping screw fasteners and steel side plates, and use this model to predict the strength and stiffness of multiple-inclined self-tapping screw connections. These results would facilitate the design of large scale connections with long rows of self-tapping screw fasteners, such as may be used for mass timber shear wall connections or splice joints for long-span timber beams.
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.
Cross-laminated timber (CLT) is gaining popularity in residential and non-residential applications in the North American construction market. CLT is very effective in resisting lateral forces resulting from wind and seismic loads. This research investigated the in-plane performance of CLT shear wall for platform-type buildings under lateral loading. Analytical models were proposed to estimate the in-plane stiffness of CLT wall panels with openings based on experimental and numerical investigations. The models estimate the in-plane stiffness under consideration of panel thickness, aspect ratios, and size and location of the openings. A sensitivity analysis was conducted to reduce the number of model parameters to those that have a significant impact on the stiffness reduction of CLT wall panels with openings. Finite element models of CLT wall connections were developed and calibrated against experimental tests. The results were incorporated into models of CLT single and coupled shear walls. Finite element analyses were conducted on CLT shear walls and the results in terms of peak displacements, peak loads and energy dissipation were in good agreement when compared against full-scale shear wall tests. A parametric study on single and coupled CLT shear walls was conducted with variation of number and type of connectors. The seismic performance of 56-single and 40-coupled CLT shear walls’ assembles for platform-type construction were evaluated. Deflection formulas were proposed for both single and coupled CLT shear walls loaded laterally in-plane that in addition to the contributions of CLT panels and connections, also account for the influence of adjacent perpendicular walls and floors above and illustrated with examples. Analytical equations were proposed to calculate the resistance of CLT shear walls accounting for the kinematic behaviour of the walls observed in experimental investigations (sliding, rocking and combined sliding-rocking) and illustrated with examples. Different configurations (number and location of hold-downs) of single and coupled CLT walls were considered. The findings presented in this thesis will contribute to the scientific body of knowledge and furthermore will be a useful tool for practitioners for the successful seismic design of CLT platform buildings in-line with the current CSA O86 provisions.
In this paper, the results of lateral loading tests on two types of CLT shear wall systems with an opening are summarized, one is the shear wall system with assembling narrow size CLT panels and another is that using one large size panel with an opening. 8 types, 13 specimens in all were tested. Load-displacement curves were obtained and characteristic values of shear performance were derived. As a result, the assembly system revealed higher ductility because of the ductility of connections between panels, while the rapture of large panel system was brittle though the shear capacity was higher than the assembly system.