This thesis investigates the performance of diamond-shaped dowel joints in concrete slabs on ground under static loads. Diamond-shaped dowels have been in common use in concrete slab construction since 1996. A comprehensive literature review revealed that published studies regarding laboratory tests and finite element modelling of diamond-shaped dowel performance were limited to primary experiments and simple numerical analysis. Importantly, the limited finite element modelling has not been verified against test data, and the scant published test data lacks clarity. The results were inconclusive, unclear and there exists different recommendations for joint stability. Some recommended design data are not based on any testing, but on inferred or extrapolated data from smaller slabs with smaller dowel thicknesses. Hence, this research provides the opportunity to enlighten the design community with real data on the performance of diamond-shaped dowel joint behaviour. The research program includes experimental, numerical modelling and parametric evaluations. In the experimental investigation, testing facilities were designed and developed in the course of this research. A total of one trial and six cast-in-place slabs encompassing two slab thicknesses, two diamond-shaped dowel thicknesses, and two dowel spacing, were tested in the structures laboratory of the Division of Civil Engineering at the University of Queensland. Joint gaps of 10 or 15 mm were used to simulate typical slab contraction causing by the shrinkage of concrete slabs. All tests were subjected to static loading to failure. This enabled slab joint response to be evaluated in terms of relative deflection, load transfer efficiency, load transfer, ultimate load and crack geometry. In addition to the experiments, numerical models were developed using the LUSAS finite element program. The model dimensions corresponded to those of the laboratory test specimens. The concrete slabs were modelled using a “multi-crack concrete model 94”. The test rig, diamond-shaped dowels and other materials were modelled as elastic materials. Results from the laboratory experiments were compared to the finite element results in order to validate the model. These models were then used to undertake a preliminary parametric study of diamond-shaped dowel performance. Criteria such as joint gap widths, dowel spacing, concrete property reduction, and dowel and slab thickness were investigated. The three main sections of this work - comprising laboratory testing, finite element modelling and parametric study evaluating have been combined to provide a betterinformed understanding of the performance of concrete slabs using diamond-shaped dowels.
| Identifer | oai:union.ndltd.org:ADTP/279124 |
| Creators | Quang Trong Do |
| Source Sets | Australiasian Digital Theses Program |
| Detected Language | English |
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