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<p>An experimental investigation was conducted to analyze the effectiveness of repairing and retrofitting the intersections of flanged concrete block shear walls using surface-bonded fiber-reinforced polymer (FRP) laminates for seismic load applications. A total of 18 specially designed flange-web intersecting wall assemblages were tested using 5 different schemes. Tests included wall intersections reinforced with unidirectional FRP with the fibers oriented perpendicular to loading direction (90°), parallel to loading direction (0°) and bi-directional (90°/0°), (90°/0°)2 and (45°/135°) to applied load direction. The behaviour of each wall specimen is discussed with respect to its failure mode, strength and deformation characteristics. Results showed that the laminates significantly increased the shear strength of concrete block shear walls junction. In addition, the fiber orientation influenced the failure mode, strength and stiffness. Moreover, depending on the fiber orientation, a significant enhancement to the post-peak load energy absorption capacity of the web-flange intersection can occur. The improved post-peak behaviour addressed the benefits of retrofitting concrete block wall intersections for seismic load applications. The FRP-retrofitted specimens were capable of reaching between 90% to 390% increase in strength compared to the umetrofitted specimen constructed with traditional steel joint reinforcement.</p> / Thesis / Master of Engineering (MEngr)

An experimental program was conducted to investigate the strength and deformations of deep beams reinforced with Carbon Fibre Reinforced Polymer (CFRP) longitudinal and transverse reinforcement. Two groups of beams were tested, with each group comprising three beams. Two of the three beams in each group were reinforced with CFRP bars while the third beam was reinforced with conventional rebars and the latter beam was used as a control specimen. Beams in group 1 had span-to-depth ratio of one, while those in group 2 had a span-to-depth ratio of two. Beams in both groups had height of 900 mm and width of 250 mm. All the beams were simply supported and were tested in four-point bending with the point loads applied at one-third of the span. The test results revealed no significant difference between the behavior of the FRP reinforced beams and the companion control beams. On the other hand due to lack of hooks at the ends of the CFRP bars, and the loss of bond between the CFRP fibres and the sand grains on the surface of the bar, the failure in the CFRP reinforced beams was caused by the loss of anchorage while in the steel reinforced beams, the failure was initiated by the yielding of the longitudinal steel, followed by the crushing of the horizontal compression strut, but the nodal zones did not fail in any of the beams. Consequently, it was concluded that CFRP reinforced deep beams could be designed using the current CSA method for conventional steel reinforced concrete deep beams, provided the anchorage or bond strength of FRP bars could be properly determined. The existing nodal efficiency factors for the CCC nodal zones, as given in the CSA A23.3. standard, could be applied to CFRP reinforced beams while the corresponding factor for the CCT zone may be conservatively assumed to be 0.68. Finally, despite the linear elastic behavior of CFRP reinforcement, deep beams reinforced with CFRP bars could be designed using strut and tie models. / Thesis / Master of Applied Science (MASc)

No / Precast concrete hollow core floor units (hcu) are widely used in all types of multistorey steel framed buildings where they bear onto the top flanges of universal beams. The steel beam is normally designed in bending, in isolation from the concrete slab, and no account is taken of the composite beam action available with the precast units. A program of combined experimental and numerical studies was undertaken that aimed at deciding on a suitable approach for the design of composite steel beams that utilize precast concrete hollow core slabs. The results show that the precast slabs may be used compositely with the steel beams in order to increase both flexural strength and stiffness at virtually no extra cost, except for the headed shear studs. For typical geometry and serial sizes, the composite beams were found to be twice as strong and three times as stiff as the equivalent isolated steel beam. The failure mode was ductile, and may have been controlled by the correct use of small quantities of tie steel and insitu infill concrete placed between the precast units.

Yes / The presence of cracks has a negative impact on the durability of concrete by providing paths for corrosive materials to the embedded steel reinforcement. Cracks in concrete can be closed using shape memory polymers (SMP) which produce a compressive stress across the crack faces. This stress has been previously found to enhance the load recovery associated with autogenous selfhealing. This paper details the experiments undertaken to incorporate SMP tendons containing polyethylene terephthalate (PET) filaments into reinforced and unreinforced 500 × 100 × 100 mm structural concrete beam samples. These tendons are activated via an electrical supply using a nickelchrome resistance wire heating system. The set-up, methodology and results of restrained shrinkage stress and crack closure experiments are explained. Crack closure of up to 85% in unreinforced beams and 26%–39% in reinforced beams is measured using crack-mouth opening displacement, microscope and digital image correlation equipment. Conclusions are made as to the effectiveness of the system and its potential for application within industry. / EPSRC for their funding of the Materials for Life (M4L) project (EP/K026631/1) and Costain Group PLC for industrial sponsorship of the project and author

M.S.

A study was performed to compare the linear static analysis and concrete design capabilities of two structural analysis and design programs - MicasPlus and STAAD III. Four structures were considered including a four span continuous beam, a two story 3-D frame, a seven story 3-D frame, and a fourteen story 3-D frame. The study compared the accuracy of the programs as well as their functionality. In the evaluation of the accuracy of analysis results, factors such as support reactions, nodal displacements, and element end forces were compared. The evaluation of the concrete design capabilities was based on comparing the reinforcement recommended by the two programs for beams and columns. For beam design, steel reinforcing bar selections for positive moment, negative moment, and shear reinforcing were compared. For column design, the cross sectional area of steel chosen by each program was compared. Factors considered in the evaluation of functionality included: user interface, ease of use, ease of learning, quality of output, documentation, flexibility, and analysis and design capabilities. / Master of Science

On the basis of freezing and thawing tests of air-entrained concretes having poor quality cherts as course aggregates subjected to three different treatments for improving durability, the following conclusions have been derived: 1. Removal of cherts lighter than the BSSD specific gravity of 2.5 by heavy liquid definitely improved the durability of the concrete. 2. Combining 50 percent durable aggregate (1/2"-1/4" size) with 50 percent cherts (1"-1/2" size) did not show any significant improvement in durability over that containing 100 percent chert. 3. As much as 12 percent chert could be blended with durable aggregate without an appreciable reduction in durability. / Master of Science

The purpose of this study is to investigate the effects of tension stiffening and softening of concrete in reinforced concrete beams and beam-columns. Analytical models of beams and beam-columns are prepared and the results compared to experimental results previously conducted by Berwanger et al. (1960) A layered model of the beams is developed and strains and stresses at various layers are computed. Moment-curvature relationships are then obtained from these. The stress-strain curves adopted are from El-Metwally and Chen (1989). The effects of tension stiffening and softening are included by adopting realistic stress-strain curves in both compression and tension. / Master of Science

Results indicate that the durability of the concrete mixes using poor aggregates can be improved to a considerable extent by moist-curing. / Master of Science