For a structure to remain serviceable, crack widths must be small enough to be acceptable from an aesthetic point of view, small enough to avoid waterproofing problems and small enough to prevent the ingress of water that may lead to corrosion of the reinforcement. Crack control is therefore an important aspect of the design of reinforced concrete structures at the serviceability limit state. Despite its importance, code methods for crack control have been developed, in the main, from laboratory observations of the instantaneous behaviour of reinforced concrete members under load and fail to account adequately for the time-dependent development of cracking. In this study numerical models have been developed to investigate timedependent cracking of reinforced concrete structures. Two approaches were adopted to simulate cracking in reinforced concrete members. The first approach is the distributed cracking approach. In this approach, steel reinforcement is smeared through the concrete elements and bond-slip between steel and concrete is accounted for indirectly by including the tension stiffening effect. The second approach is the localized cracking approach, in which concrete fracture models are used in conjunction with bond-slip interface elements to model stress transfer between concrete and steel. Creep of concrete has been incorporated into the models by adopting the principle of superposition and the time-dependent development of shrinkage strain of concrete is modelled using an approximating function. Both creep and shrinkage were treated as inelastic pre-strains and applied to the discretized structure as equivalent nodal forces. Apart from material non-linearity, non-linearity arising from large deformation was also accounted for using the updated Lagrangian formulation. The numerical models were used to simulate a series of laboratory tests for verification purposes. The models were assessed critically by comparing the numerical results with the test data and the numerical results are shown to have good correlations with the test results. In addition, a comparison was undertaken among the numerical models and the pros and cons of each model were evaluated. A series of controlled parametric numerical experiments was devised and carried out using one of the numerical models. Various parameters were identified and investigated in the parametric study. The effects of the parameters were thoroughly examined and the interactions between the parameters were discussed in detail.
| Identifer | oai:union.ndltd.org:ADTP/235866 |
| Date | January 2004 |
| Creators | Chong, Kak Tien, Civil & Environmental Engineering, Faculty of Engineering, UNSW |
| Publisher | Awarded by:University of New South Wales. School of Civil & Environmental Engineering |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Kak Tien Chong, http://unsworks.unsw.edu.au/copyright |
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