The objectives of this research were to investigate the heat resistant performance of a structural adhesive and to analyze the contribution of the adhesive to the chemical emissions from the glued wood products affected by the elevated temperatures. Phenol-resorcinolormaldehyde (PRF) and two wood species, southern pine (Pinus palustris) and Douglasir (Pseudotsuga menziesii), were investigated. The dynamic mechanical analysis (DMA) test results showed that the heat durability performance of cured PRF resin was better than that of the two wood species used in this study. The results indicated that the fire safety of PRF bonded wood products should be comparable to solid wood products. The pyroysis products obtained from pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) system showed that most of the pyrolysis products of glued wood samples were same as those of wood and adhesive samples at the same temperature level except a few compounds, such as carbon disulfide, Cyclopropyl carbinol, acetaldehyde, furfural and others.

The use of engineered wood products (EWP) in residential construction has increased in recent years. Most specifications for the installation of these components are found in proprietary manufacturer literature rather than in the building code. Although some home inspections include EWP prescriptive compliance, very little applied and academic literature addresses this practice. This lack of practical information and the lack of standardized inspection methods can result in undetected non-compliant EWP installations that fail to meet the minimum safety provisions of the building code. The goal of this project was to develop a visual inspection methodology, associated knowledge base, and software application for the inspection of EWPs and connector hardware (CH) in new residential construction at the pre-drywall stage. The methodology was based upon subject matter expert (SME) inputs and validation was derived from the use of a modified Delphi method that was able to the gather, collate, refine, and validate the research process and outputs based on the expertise of the subject matter experts. The concept of high face validity was used to establish project validity. Installation problems with EWPs and CH were noted by the SMEs partly because the use and installation instructions for proprietary products are not found in building codes. Building code officials (BCO) and home inspector (HI) SME responses indicated a need for a methodology and software to aid in the inspection process. Although authoritative reference materials for prescriptive installation are available, the scope of material is not consistent between manufacturers, and is presented in different formats for different brands. The developed software application provides ready access to reference materials needed for EWP and CH installations. No widely accepted inspection methodology is available, although the HI SMEs used systematic inspection methods. Inspection methods such as the top-down method and sighting along the patterns of repetitious framing elements can improve the detection of non-compliant installations. BCO and HI SMEs identified both component-specific and zone-specific techniques as a part of the systematic inspection methodology. Definable high risk areas for each EWP and CH were identified and the associated inspection methods may help the inspector reduce the incidence of undetected problem areas. Knowledge of the high-risk areas may also enhance the inspection. The developed software application was found to be a useful inspection tool. BCO and HI SMEs determined that functions of the computer software necessary for use included ease of use, onboard reference materials, specific inspection techniques, prepared comments, and technical illustrations. / Ph. D.

Engineered wood I-joists have grown in popularity as flooring and roofing structural systems in the past 30 years, replacing solid sawn lumber joists. Typical wood I-joists are manufactured with a very slender section, which is desirable to achieve higher flexural capacities and longer spans; however, this makes them susceptible to lateral torsional buckling failure. Continuous beam spans and uplift forces on roof uplift are potential scenarios where lateral instability can occur and reflects the need to investigate the lateral torsional buckling behavior of wood I-joists. Within this context, the present study conducts an experimental investigation on the material properties and the critical buckling load of 42 wood I-joist specimens. A 3D finite element model is built using the experimentally determined material parameters to effectively predict the observed buckling behavior of the specimens while also accounting for initial imperfections in the joists. The adequacy of other analytical models to predict the critical buckling load of wood I-joists are also investigated. It is demonstrated that the American design standard underestimates the critical buckling load of wood I-joists while the classical theory provides an adequate estimate of the buckling capacity. Furthermore, the effects of initial imperfections on the lateral torsional buckling behavior are discussed. The developed and verified FE model is used to reproduce the nonlinear buckling behavior of the wood I-joist and also to provide an accurate estimate of the lateral torsional buckling capacity using the linear buckling analysis.

Engineered wood products (EWP) are becoming extremely popular and a viable material option for the construction of residential, commercial, and hybrid buildings. Cross-laminated timber (CLT) is among one of the many EWP available in North America, which can be utilized for many different applications such as: walls, floors, and roofs. Despite the available requirements in the Canadian blast design standard (CSA, 2012) with regard to the design of wood structures, there are currently no provisions on how to retrofit timber structures to improve their performance when subjected to blast loads. The current study is aimed at investigating the effect of different retrofitting alternatives in order to improve the overall behaviour of CLT when exposed to out-of-plane bending. The experimental program examined the behaviour of seventeen reinforced CLT slabs. Testing was conducted at the University of Ottawa by means of a shock tube capable of simulating high strain rates similar to those experienced during a blast event. The current study was divided into two phases. The first consisted of CLT slabs retrofitted with steel straps where strap spacing, location, and order of installation was investigated. The second phase focused on the development of dynamic properties of CLT panels when reinforced with GFRP. Lay-up configuration and fabric orientation were among the parameters explored. The results from the experimental program show that reinforcing the panels with steel straps had minimal effect on the ultimate strength, but significant levels of post peak resistance and ductility was achieved. The horizontal straps were able to restrict the failure to small regions and to promote flexural failure by preventing rolling shear failure. It also eliminated flying debris and enhanced the ultimate strength, stiffness as well as ductility. Applying GFRP layers enhanced the overall behaviour of the slab resulting in a significant increase in peak resistance, ductility, and stiffness when compared to the dynamic results of an unretrofitted panel. The post peak resistance was also greatly improved. In particular, applying stacked quadraxial lay-up configuration significantly improved the ductility and resulted in the greatest post peak resistance. The effect of steel straps on damaged and retrofitted was relatively minimal, and only partial recovery of the resistance and the stiffness was achieved. GFRP with full confinement yielded better performance compared to the unretrofitted and undamaged counterpart. More work is needed to quantify the benefits of using GFRP in these applications.

The advancement in manufacturing technologies to produce high-performing engineered wood products (EWP) has allowed wood to be utilized beyond the traditional low-rise light-frame structures and to become a viable material option for much larger structures. Although glued-laminated timber (glulam) is included as a material option in the current blast code (CSA, 2012), its response to blast loading is not yet well documented. An experimental program investigating the behaviour of seventy glulam beams and columns was developed with focus on establishing the dynamic characteristics of glulam beams and columns with and without the effect of FRP reinforcement. A shock tube capable of simulating high strain rates similar to those experienced during blast was used. Thirty-eight beams with three different cross-sections were tested statically and dynamically to establish the high strain rate effects (dynamic increase factor). Six columns were also tested dynamically with axial load levels ranging from 15 to 75 % of the columns’ compression design capacity. Different retrofit configurations varying from simple tension reinforcement to U-shaped tension reinforcement with confinement using both unidirectional and bi-directional FRP were investigated on a total of twenty-six beams. A procedure capturing the strain-rate effects, variable axial load and FRP, was developed and found to be capable of predicting the flexural behaviour of the beams up to maximum resistance with reasonable accuracy when compared to experimentally obtained static and dynamic resistance curves. Implications on the design of both retrofitted and unretrofitted specimens are also discussed.

For structural engineers, the two most important design criteria are utility andsafety. It is about making sure that a structural component is reliable enough not toendanger any of a building's users, while at the same time being as sustainable andefficiently designed as possible. In other words, an element must be safe enough towithstand the improbability and sufficiently cheap to be relevant for the design.Considering this, using a material such as wood instead of metal may prove to be asustainable alternative for certain building components.Timber can be designed to sustain high temperatures and fire; it has a high strengthrelative to its weight and is naturally produced. Furthermore, an engineered woodproduct such as birch plywood has proven very strong in structural applications,especially when glued. Therefore, birch plywood has great potential as a reliablematerial in structural components. In this work, a total of 24 specimens with birchplywood connections were tested experimentally.The specimens were designed to enforce stress states that would occur in actualtrusses. Additionally, Specimens were assembled with two different connectionmethods, one being a dowel-type connection and the other being a glued-type. Eachtype of connection was tested in both tension and compression, with a total of threerepetitions each. For the glued-type specimens, birch plywood plates wereinvestigated in three different angles to the face grain; 0°, 5° and 15°. Theload-displacement relationships and the failure modes are of specific interest in thisthesis.Test results showed that failure modes were semi-brittle and distinct, and the testsshowed that glued-type connections withstood 37% higher loads than dowelledtypes. Specimens might withstand even higher loads if gluing were performed in amore controlled environment. The load-to-face-grain angle of plywood also had asignificant impact on the capacity of connections. For the 0°-specimens with gluedconnections tested in compression, no failures occurred in the plywood, and testsreached loads as high as 82 kN. Calculations were made estimating the load capacityas high as 95 kN, but possibly a more realistic approximation would be 85 kN. Thiswould imply that the 0°-specimens are around 20% stronger than the 15°-specimensand approximately 17,7% stronger than the 5°-specimens tested in compression.Birch plywood is promising to be used in connections of timber structures whereplates transfer forces between structural elements.