Vertical wind shear is computed between the 28 possible pairs of the first 8 mandatory radiosonde levels. A hail severity index is defined. Statistically significant correlations between strong shear and hail-free days are found in 11 shear layers. Strong shears are also found to occur more frequently with low and high severity indices than with intermediate severity indices. [...]

Bridges consisting of steel plate girders and composite concrete deck slabs are common throughout North America. For a typical highway application, these composite bridges are constructed with a cast-in-place concrete deck; however, some composite bridge designs utilize precast concrete deck panels. For example, bridges built on temporary access roads which service resource industries throughout Western Canada often employ composite bridges that consist of steel plate girders and precast concrete deck panels. For spans between 18- to 36 metres, permanent bridges currently present the best economy; although, portable structures would be preferred on these temporary roads so that the bridge could be relocated after the road is decommissioned. This study proposes a shear connection between steel plate girders and precast concrete deck panels, which allows fastening, and unfastening, of these two components enabling a portable composite bridge. In total, ten connection concepts were developed during this study and a multi-criteria assessment was performed to evaluate each concept respectively. Based on the outcome of this multi-criteria assessment, and subsequent sensitivity analysis, a preferred connection was established and a finite element model was developed for the analysis of composite bridge girders. For the initial development of the finite element model, the test set up and experimental findings of a test program by other researchers was employed so that the finite element analysis results could be compared to those reported from a physical experiment. Following this initial finite element analysis, full scale composite bridge girders were modelled so that the influence of the proposed shear connection on the behaviour of a composite girder could be studied. The model was verified for its ability to capture the possible effects of flange buckling, web buckling, and lateral torsional buckling of the steel plate girder. It was then confirmed that these local responses do not influence the performance of the proposed portable composite bridge system. A parametric study was also performed in which the effect of shear connection stiffness and spacing on the behaviour of the composite girder was investigated. This parametric study allowed the sensitivity of the proposed connection to variations in these two parameters to be assessed and also allowed preliminary study of the performance of composite girders with alternative shear connection designs.

This thesis discusses the results of an experimental program designed to investigate the effect of corrosion on the behaviour of shear critical reinforced concrete (RC) beams. The results of twenty RC beams (ten deep beams and ten slender beams) are described and discussed. The test variables included: corrosion level (2.5%, 5% and 7.5%) and existence of stirrups (beams without stirrups and beams with stirrups). The feasibility of repairing the corroded shear critical RC beams with CFRP laminates was also investigated. Sixteen specimens were corroded using an accelerated corrosion technique whereas four specimens acted as control un-corroded. Following the corrosion phase, all specimens were tested to failure under three point bending. Test results revealed that the corrosion does not adversely affect the behaviour of shear critical RC beams rather it improves their behaviour. It was found that corrosion changed the failure mode of the corroded beams. The control un-corroded deep beams (beams with and without stirrups) failed in shear-compression failure whereas corroded deep beams (beams with and without stirrups) failed by splitting of the compression strut. The control un-corroded slender beams (beams with and without stirrups) failed in diagonal tension failure whereas the corroded slender beams failed in anchorage failure (beams without stirrups) and flexural failure (beams with stirrups). The analysis of the results showed that corrosion changed the load transfer mechanism and the change of failure mode was associated with the mechanism. The load transfer mechanism changed from a combination of beam and arch action in the control un-corroded deep beams to pure arch action in the corroded deep beams. The load transfer mechanism changed from pure beam action in the control un-corroded slender beams to pure arch action in the corroded slender beams. Two strut and tie models are proposed: one for corroded deep beams and one for corroded slender beams. The ultimate loads of the corroded beams were predicted using these struts and tie models and compared with the experimental results. A very good correlation was found between predicted and experimental results.

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Dysfunction of the vascular endothelium can initiate atherosclerosis. Mechanical forces, particularly wall shear stress (WSS) are believed to cause endothelial dysfunction. Present in vitro cell culture models are often simplified and thus, ignore the wall shear stress spatial gradients inherent in complex geometries. The aim of this project was to study endothelial cell response in an anatomically correct right coronary artery model (RCA) under more physiologically realistic flow conditions. / Human Abdominal Aortic Endothelial Cells (HAAECs) were seeded in the lumen of a pre-treated faithful RCA and a straight tubular model. The cells were subjected to steady or non-reversing oscillatory flow (Re=196, alpha=1.82) at a mean physiological flow rate of 20 dynes/cm2 for 8, 12 and 24 hours of flow. The results show that under all flow conditions, the cells became progressively more elongated and aligned. Moreover, differences in endothelial morphology in the inner (myocardial) and outer (pericardial) walls were seen in the inlet region. The morphologic adaptation to steady and oscillatory flow was similar. The results suggest that spatial, not temporal gradients in shear in the inlet region are responsible for the differential endothelial cell response.

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