This study examines the effects of various rib properties and reinforced section geometries on the splitting force distribution around tensile lapped splices. The study makes use of a test specimen which idealizes the situation that exists in a tensile lapped splice between adjacent lateral cracks. The test specimen always failed by a longitudinal splitting of the concrete cover along a predefined failure plane. During the study the Influence of relative rib area, rib profile, amount of secondary link reinforcement, lateral pressure and bar spacing within the lap on the ultimate bond strength of the lap were examined. It was found that, for hot rolled (untwisted) deformed bars with crescent shaped ribs the orientation of the ribs to the splitting plane significantly affected the ultimate bond strength of the test specimen and, whilst the relative rib area was a good measure of a deformed bars performance In bond, it could not distinguish between the different orientations used. Further, since the maximum percentage Increase In ultimate bond stress for the same bar between orientations was of a similar magnitude to that observed for a doubling of a bars relative rib area the author recommends that bar orientation be taken into account when detailing tensile lapped splices. The presence of link steel perpendicular to the splitting plane did not significantly influence the ultimate bond strength of the model test specimen although the presence of lateral pressure did. The stress in the links at the occurrence of a full length splitting crack was less than 100 N/mm2. The finite element method was used to examine the two fundamental hypotheses describing the bond action of deformed reinforcing bars and to examine the implications of the assumption that the splitting forces around the circumference of a reinforcing bar are distributed proportionally to the rib height. The finite element analysis was also used to study the effect of varying the distance between the lapped bars on the spitting force distribution around the lapped bars. The results of a linear elastic analysis showed that both rib profile and bar spacing had a significant effect on the distribution of splitting forces around a tension lapped splice

published_or_final_version / abstract / toc / Mechanical Engineering / Master / Master of Philosophy

published_or_final_version / Industrial Engineering / Master / Master of Philosophy

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No description available.

The need for the development of a rigorous analytical model of the lumbar spine to clarify the role of mechanical factors in low-back disorders has long been recognized. In response to this need, a general three dimensional nonlinear finite element program has been developed as part of this work and has been applied to the analysis of a lumbar L(,2-3) joint including the posterior elements. The analysis accounts for both the material and geometric nonlinearities and is based on a representation of the nucleus as an incompressible inviscid fluid and of the annulus as a composite of collagenous fibres embedded in a matrix of ground substance. The facet articulation has been accounted for by treating it as a general moving contact problem. The ligaments have been modelled as a collection of nonlinear axial elements. The geometry of the finite element model is based on in-vitro measurements. / The response of the joint under single compression, single flexion, single extension and also under flexion or extension combined with compression and sagittal shear has been analyzed for both the normal and degenerated states of the nucleus. Validity of the model has then been established by a comparison of those predictions which are also amenable to direct measurements. The states of strain and stress in different components of the lumbar joint have been thoroughly studied under all the foregoing loading conditions. / Those elements of the joint predicted to be vulnerable to mechanical failure or damage under the above types of loading have been identified. These results have been correlated with the lumbar joint injuries reported clinically. Furthermore, some joint injury mechanisms and degeneration processes have been proposed and the supporting clinical evidences have been presented.

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Reinforced concrete beam-column joints (BCJs) are commonly used in structures such as parking garages, multi-storey industrial buildings and road overpasses, which might be exposed to extreme weathering conditions and the application of de-icing salts. The use of the non-corrodible fiber-reinforced polymer (FRP) reinforcing bars in such structures is beneficial to overcome the steel-corrosion problems. However, FRP materials exhibit linear-elastic stress-strain characteristics up to failure, which raises concerns on their performance in BCJs where energy dissipation, through plastic behaviour, is required. The objective of this research project is to assess the seismic behaviour of concrete BCJs reinforced with FRP bars and stirrups. An experimental program was conducted at the University of Manitoba to participate in achieving this objective. Eight full-scale exterior T-shaped BCJs prototypes were constructed and tested under simulated seismic load conditions. The longitudinal and transversal reinforcement types and ratios for the beam and the columns were the main investigated parameters. The experimental results showed that the GFRP reinforced joints can successfully sustain a 4.0% drift ratio without any significant residual deformation. This indicates the feasibility of using GFRP bars and stirrups as reinforcement in the BCJs subjected to seismic-type loading. It was also concluded that, increasing the beam reinforcement ratio, while satisfying the strong column-weak beam concept, can enhance the ability of the joint to dissipate seismic energy. An analytical investigation was conducted through constructing a finite element model using ANSYS-software. The model was verified against the experimental results in this research. Then, a parametric study was performed on number of different parameters known to affect such joints including column axial load, concrete compressive strength, flexural strength ratio and joint transverse reinforcement. It was concluded that 70% of the column axial load capacity can be recommended as an upper limit to the applied axial loads on the column to avoid damage occurrence within the joint. It was also concluded that a minimum flexural strength ratio of 1.50 is recommended to ensure the strong-column weak-beam mechanism. In addition, a minimum joint transverse reinforcement ratio of 0.60% is recommended to insure that the failure will not occur in the joint zone.

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No description available.