<p>This dissertation presents an inelastic analysis of the behaviour of composite beams with ribbed metal deck.</p> <p>A layered finite element model is used to allow for any variation in material properties through the thickness. An incremental and iterative technique is adopted using the tangent modulus stiffness approach.</p> <p>The dependability of the model is checked by means of comparison with some experimental results, obtained from testing composite beams with solid and ribbed slabs.</p> <p>A study of the effect of the type of loading and the transverse moment in the slab on the deformation and the ultimate capacity of composite beams with ribbed metal deck, is presented.</p> <p>The effective width of composite beams with ribbed metal deck, subjected to uniformly distributed load, is investigated. The effective width in the inelastic stage and at the ultimate load are also studied.</p> <p>Finally, a study of the longitudinal cracking of composite beams with ribbed metal deck, is presented. Some design recommendations are presented to account for the longitudinal cracking of composite beams with ribbed metal deck, subjected to a uniformly distributed load over the entire slab.</p> / Doctor of Philosophy (PhD)

<p>The lack of understanding the behaviour of concrete masonry and the complex interaction existing between its components (block, mortar, and grout) at failure may be the cause of the continued use of the code's working stress method. This approach could underestimate the potentials of masonry as a construction material. It is the main objective of this investigation to provide a better understanding of concrete masonry behaviour under different in-plane load conditions (compression, tension, shear and biaxial stresses) considering the anisotropic nature of masonry as a composite material. This understanding was gained through a combined experimental and analytical investigation.</p> <p>In the experimental study, 323 masonry assemblages were tested under compression normal and parallel to the bed joints, splitting tension at different orientations from the bed joints, shear along the bed joint with different levels of precompression, and off-axis compression and tension to produce biaxial states of stresses along the bed and head joints. The test material variables were mortar type, grout strength, and bed joint reinforcement.</p> <p>Analytical strength formulas, based on a "strength" approach, are proposed to express, in quantitative terms, the assemblage compressive strength normal to the bed joints, tensile strength normal, diagonal, and parallel to the bed joints, and shear strength along the bed joint with and without precompression. The applicability of the failure theories for both isotropic and composite materials to masonry were examined. Failure criteria are proposed to predict the strength and the failure mode of concrete masonry under biaxial stresses taking into account the anisotropic nature of masonry as a brittle composite material. Design code provisions (CSA S 304) for plain masonry are reviewed.</p> / Doctor of Philosophy (PhD)

<p>No rigorous explanation exists for the behaviour of reinforced concrete joints. The lack of understanding the complex interaction may account for continued use of inadequate joint details particularly for knee joints subjected to opening moments. The object of this research was to provide a better understanding of joint behaviour through a combined experimental and analytical investigation.</p> <p>In the experimental program, 6 specimens with different types of joint details were tested under opening moment. These details reflected recent recommendations by other investigators and some adaptations of their ideas. The results served as evidence of the ability to produce effective and simple details as well as serving as a basis for evaluating the reliability of the analytical model.</p> <p>A method of analysis has been developed using the finite element method to model the behaviour of reinforced concrete including the interactions between concrete and steel in the form of bond and dowel forces. One of the principle features of this method of analysis is the built in ability to trace the propagation, location and orientation of cracking. This feature was tested by comparing predicted behaviour of beams failing in shear and flexure with test results. Very good agreement with the well documented phenomena of various modes of cracking and failure provided evidence of the validity of the analytical method.</p> <p>The analyses of the joints reproduced cracking patterns and sequences as well as capacities which are quite close to the test results. The analytical information helped to identify the primary causes of failure of premature failure and thereby provided a more rational basis for suggesting alternate joint details which will behave much better than inadequate details which are currently recommended.</p> / Doctor of Philosophy (PhD)

<p>Fiber reinforced polymer (FRP) - confined concrete-steel composite columns have been recently introduced as a retrofit technique for structural steel columns. This technique involves placing an FRP tube around an in situ steel column and subsequently filling the void between the steel section and the FRP tube with concrete to create a composite column. The composite action occurs due to the concrete encasing the steel section and the FRP confining the concrete. An experimental investigation has been undertaken to evaluate: the effect of adding a steel W section to confined concrete; the effect of using a split tube system as a practical application technique; and the effect of shrinkage reducing admixture in confined concrete. A total of eighteen stub columns, consisting of six different column types were tested to meet these objectives. It was found that the load-displacement response of confined concrete that includes a steel W section is similar to the response of confined concrete plus the elastic-perfectly plastic steel contribution. Experimental findings demonstrate the enhanced performance of the proposed split tube retrofit technique. An analytical model was used to predict the response of the different column types. A method is proposed to incorporate the increased stiffness of the FRP jacket in the split tube system and is shown to be an improvement on the original model. A parametric study was also performed on the revised model.</p> / Master of Applied Science (MASc)

<p>Denser-than-water, non-aqueous phase liquids (DNAPLs) are contaminants that pose a serious threat to groundwater quality because of their high toxicity and ease of mobility once released into the groundwater system. In order to effectively assess the risk to human and ecological health, and to select an appropriate remediation strategy, the DNAPL source zone must be accurately characterized. The area of the DNAPL-water interface is one feature commonly used to characterize the DNAPL source zone; it is significant as it measures the surface area available for DNAPL mass transfer into the groundwater causing contamination. Additionally, many remediation strategies depend on the inter-phase mass transfer. At present, interfacial tracer tests have been successful for determining the DNAPL-water interfacial area in unconsolidated porous media, yet no study has applied this technique to fractured rock systems. The purpose of this study was to develop an interfacial tracer technique for determining the DNAPL-water interfacial area, anw in fractured rock environments. The experimental design involved four phases (1) characterizing two fracture planes using hydraulic and tracer studies, (2) trapping a known mass of a DNAPL, hydrofluoroether 7100 (HFE7I00) in the fractured rock systems, (3) performing interfacial tracer tests with sodium dodecyl benzene sulphate, sodium dodecylbenzene sulphonate (SDBS) as the reactive tracer and acid yellow 17 as the non-reactive tracer to derive an anw measurement, and (4) verifying the anw value through visualization using digital image analysis. While the interfacial tracer technique was only applied to two unique fractures in this study, it demonstrates the ability to obtain a measure of the DNAPL-water contact area, and offers an additional tool for the characterization of DNAPL source zones at the lab-scale; further work is required to evaluate the tracer test methodology for field applications.</p> / Master of Applied Science (MASc)

<p>The mechanistic design of flexible pavement systems requires the specification of the mechanical properties of unbound granular base/subbase material. The influence of the degree of saturation, low confining pressure, and suction (measured through an SWCC test) on the monotonic and cyclic behavior of granular base/subbase was investigated to obtain a better understanding of granular base behavior corresponding to condition encountered in situ.</p> <p>In order to achieve this understanding, a series of quick-undrained (UU) monotonic and cyclic triaxial tests were conducted on sand specimens (Material 1 and Material 2) at ambient temperature, with the degree of saturation ranging from 24% to 66%, and confining pressures from 4 kPa to 64 kPa. Additional tests were conducted under UU conditions to determine the effects of freeze-thaw on permanent deformation (plastic strain) and the memory of base material.</p> <p>The results showed that shear strength and modulus of elasticity increase with increasing confining pressure, and decrease with increasing water content (degree of saturation), as expected. The stress-strain response of the specimens was generally ductile with higher confining pressure and degree of saturation causing greater ductility. The cyclic test results showed that there was a monotonic relationship between accumulated plastic strain and confining pressure, given that ratio of peak shear stress to confining presseure is constant. The research also showed that there is an almost linear relationship between increase plastic strain and moisture content after cyclic tests or freeze-thaw. Overall it was found that the effect of saturation and change in suction on shear strength and modulus of elasticity is not as significant as the effect of confining pressure. However, it was found that the effects of saturation, suction, and confining pressure were almost equally important when it comes to plastic strain development during cyclic tests or freeze-thaw loading.</p> / Master of Applied Science (MASc)

<p>Many reinforced concrete frame structures were designed and constructed before the development of seismic codes or according to earlier versions of seismic codes. Thus, these structures were designed only for gravity loads or for much lower lateral loads than the loads specified by the current seismic codes. Non-ductile reinforcement details in the form of insufficient shear reinforcement in the joint zone or inadequate anchorage length of beam bars are some of the main characterisitics of these structures. Post-earthquake investigations confirmed the vulnerability of these structures to severe earthquakes. Poorly designed joints, especially the exterior ones have been identified as critical structural elements that could fail prematurely. Many failure cases were recorded as a result of joint shear failure or anchorage failure of beam bars.</p> <p>The objectives of this study were to investigate the seismic behaviour of existing concrete frames under simulated seismic loads as well as to develop effective rehabilitation schemes for strengthening concrete frames with non-ductile reinforcement details. The experimental part of this study was conducted to investigate the effect of non-ductile reinforcement details on the behaviour of the joint. Several rehabilitation schemes were proposed to mitigate the hazards caused by such poorly detailed concrete joints. These strengthening schemes included using of externally bonded fibre reinforced polymer (FRP) sheets and steel elements. Twelve exterior full-scale beam-column joints were tested under quasi-static cyclic loading. The speciments were divided into three groups, the first group has no transverse reinforcement in the joint zone, the second group has inadequate embedment length of beam bars and the last group has both no ties in the joint and inadequate anchorage length of beam bars. The joint shear resistance was improved using FRP jacket, whereas the inadequate anchorage conditions of beam bars were improved using FRP sheets or steel elements. The analytical part of this study was conducted to study the effect of FRP wraps on the compression behaviour of axially-loaded concrete elements and to develop analytical models to predict the shear response of concrete joints without transverse reinforcement, with transverse reinforcement or with FRP sheets. The proposed models were introduced into a non-linear dynamic analysis program and then used to simulate existing and rehabilitated beam-column subassemblies.</p> <p>From the test results, several rehabilitation systems to improve the performance of non-ductile concrete joints were proposed and successfully evaluated. FRP jacket proved to be effective in upgrading the joint shear resistance. FRP sheets and steel elements were effective in upgrading the anchorage conditions of beam bars. The proposed shear and materials models, which were introduced into a macro model to represent beam-column joints, were capable of representing the cyclic behaviour of existing and rehabilitated beam-column subassemblies. These models would help the design engineers to assess existing structures and propose practical rehabilitation schemes for these structures.</p> / Doctor of Philosophy (PhD)

Master of Engineering (ME)

<p>[Missing pages: 147,229]</p> / <p>An analytical technique for determining the inelastic responses of coupled shear wall structures is developed based on the transfer matrix technique in combination with the continuum method. It applies to nonuniform coupled shear walls resting on flexible foundations. The P-Δ effect, the possibilities of formation of the yield hinges at the ends of the connecting beams and at the bases of the walls, the effects of the rotational ductility factor of the connecting beams are also considered in this analysis.</p> <p>Based on this technique, a study is made on a two interconnected coupled shear wall model to simulate the earthquake response of a typical coupled shear wall building with different exterior and interior walls. The dynamic responses of these coupled shear walls are then compared with those obtained by conventional analysis of a single coupled shear wall to evaluate the effect of load transfer between dissimilar coupled shear walls within a building during an earthquake.</p> / Master of Engineering (ME)

<p>Tests on six composite open-web steel joists and concrete slabs with ribbed metal decking are described. The joists spanned 50 ft. and were loaded by two symmetrical point loads. Different types of shear connectors and different degrees of connection were used. Tests results are shown and compared with analytical results obtained from elastic theories. An ultimate strength design method is proposed.</p> / Master of Engineering (ME)