Objective modelling of reinforced concrete structures

• Main Author: Khalid, Huma
• Other Authors: Izzuddin, Bassam
• Published: Imperial College London 2012
• Subjects: 620.137
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.550919

The finite element (FE) method is a powerful technique that can provide numerical solutions to the response of reinforced concrete (RC) structures. However, results obtained from FE models are often not objective in the sense that the numerical solutions of FE models depend on aspects such as the selection of mesh size, load step size etc. FE model objectivity aims at the development of FE models for which the predicted results converge with refinement. To date, many research studies have been carried out on the objectivity of FE solutions for RC structures. However, considerable uncertainty still exists because of the many parameters which are involved in the analysis. The parameters affecting FE analysis of RC structures may be divided into two groups: material parameters and procedural parameters. The main parameters related to the material behaviour are tension softening and interaction between steel reinforcement and concrete. On the other hand, the procedural parameters which affect directly the results of the analysis are the load step, mesh size, iterative scheme, and number of cracks allowed per load step, numerical integration rule, and the use of static vs. dynamic analysis. In an effort to investigate these parameters, the current research is primarily aimed towards developing finite element formulations and solution procedures that facilitate the objective modelling of RC structures. The present study focuses on a subset of the above parameters that appear to be most relevant to objective modelling. Two new formulations have been developed in this work which allows the objective modelling of RC beam-column members, including geometric and material nonlinearity as well as bond slip. Particular emphasis is placed on predicting crack localisation in the concrete and stress concentrations in the steel reinforcement across such cracks, as this is particularly relevant to the modelling of RC structures under extreme loading. Several verification and validation studies are presented in the thesis to illustrate the key features of the proposed formulations and their applicability to the objective modelling of RC framed structures.