Current Research

TCC

Timber-Concrete Composite Connector Systems

Timber-Concrete Composite systems have been employed as an efficient solution in medium span structural applications; their use remains largely confined to European countries. A large number of precedents for T-beam configurations exist; however, the growing availability of flat plate engineered wood products offers greater versatility in terms of floor plans and architectural expression in modern timber and hybrid structures. A research program investigates the performance of five different connector types (a post-installed screw system, cast-in screws, glued-in steel mesh, adhesive bonded, and mechanical interlocking) in Cross-Laminated-Timber, Laminated-Veneer-Lumber, and Laminated-Strand-Lumber. UBC TCC Test Report

Rod

Connections with Multiple Glued-in Rods

Most previous research has focused on testing single rod joints to evaluate the influence of various connection parameters. In practice, however, multiple steel rods are required to transfer the loads from one structural component to the next. This project investigates joints composed of glued-in steel rods in glue-laminated timber. The influence of the anchorage length was studied to establish performance benchmarks; then joints with multiple rods (two, three and four rods with the spacing between rods varied) were manufactured and tested under uniaxial quasi-static tension loading.

Rivet

Timber Rivets in Laminated Veneer Lumber

Timber Rivets are oval-shaped nails made from high-strength steel that allow for strong and ductile timber connections. Significant research has been conducted regarding the application of Timber Rivets to Laminated Veneer Lumber (LVL). As a result, the Johansen Yield Model has been complemented with new failure models and design equations that predict brittle failure modes. Recently, new vertically laminated LVL products are available on the marked that can be used in beam applications. The objective of the research was to evaluate the feasibility of using the novel models to predict the failure modes and capacities of Timber Rivet connections in LVL.

FFTT connection

Connection for timber-steel hybrid system

Hybrid systems have grown in popularity over the past years but the lack of established design guidelines has delayed the construction of the hybrid structures. This project focuses on the detailed design of hybrid systems through an experimental study on an innovative timber-steel hybrid system called “FFTT”. The system relies on CLT wall panels for gravity and lateral load resistance and embedded steel sections for ductility under earthquake loads. An important step towards the practical application of the system is obtaining the proof that the connections facilitate the desired ductile failure mode.

FFTT system

Nonlinear dynamic analyses of timber-steel-hybrid system

Climate change has increased the demand for designing structures with more sustainable materials. The “Finding the Forest Through the Trees” (FFTT) system is a new hybrid system for high rise structures which combines the advantages of timber and steel as building materials. This research focuses on utilizing finite element models to capture the seismic response of the FFTT system and help developing practical design guidance.

CLT shear connection

High performance CLT shear connection

The research investigated the feasibility of using STS assemblies for the shear connection of the CLT roof diaphragm of a large storage facility where a high-performance and low-manufacturing-cost solution was required. Full-scale specimens were subjected to quasi-static and reversed-cyclic loading. Excellent structural performance in terms of strength and stiffness was obtained while still providing the required ductility for the system to be used in seismic applications. The data obtained from the testing will allow engineers to specify lateral load resisting systems for large scale CLT structures.

Design tool for adhesively bonded joints

The research aims to offer a reliable, robust and practical design tool for dimensioning load bearing adhesively bonded timber joints for structural applications, either between timber members, but also between timber and other materials, as fiber
reinforced polymers and steel, considering static short and long-term, climate and fatigue load. The research is funded by the Swiss National Science Foundation, and carried out in collaboration with structural engineers and architects from Switzerland, mechanical engineers from Portugal, and reliability specialists from Norway.

Use of off-axis samples

For brittle materials such as wood under tension and shear loading, statistically based size effects on strength are adequately explained by theories such as the Weibull theory. The material parameters needed to formulate a failure criterion can be determined according to standard tests on samples exhibiting radically different shapes and volumes. An increase of accuracy can be obtained by using a less disparate set of tests to determine the material strengths; e.g. with off-axis samples that are identical in geometry and volume, and allow formulating failure criteria more straightforwardly.

Timber Joints with Glued-in Rods

Timber joints with glued-in rods constitute a promising solution for numerous structural applications; in Canada they are, however, not yet widely used, partially for a lack of design guidance and the use of very conservative empirical safety factors. Such joints are used firstly to transfer forces between structural members and secondly to repair damaged parts, and have a series of advantages, e.g., the formation of very stiff connections, good fire properties and improved aesthetics. The research is funded through a NSERC grant.