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University of Sheffield


Civil Engineering/ Structural



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This thesis describes research aimed at developing an understanding of structural behaviour of reinforced concrete sections with repaired compression zones in order to develop analytical and design procedures at the serviceability and ultimate limit state.  The work, therefore includes an experimental test programme to study the significance of the most important parameters namely depth of repair. length of repair and properties of repair material.  The test results are used to support the parallel development of an analytical method to predict the flexural behaviour of beams after repair.

On the basis of a review of the literature on repair materials and techniques, four currently available repair materials were selected for use in this investigation; low strength concrete, high strength concrete, polymer mortar and epoxy mortar.  The properties of these repair materials together with the concrete substrate and reinforcing steel were investigated to provide data on their stress/strain characteristics for inclusion in the analytical model.  Detailed investigations of flexural behavior under short and long term loading were carried out together with a preliminary assessment of the shear behavior of such repaired beams.

     A computer program was developed to carry out both elastic analysis and analysis at ultimate moment state.  This analysis was based on non linear stress/­strain relations for the material in        compression.  Numerical integration was used in order to solve the developed formulations.  A simplified design method was derived based on defining the equivalent rectangular stress            block which gives the same magnitude and location of the force in the compression zone.  The results obtained from this method are compared with the computer program and test results.       The test results revealed many information about the behavior of a such repaired beam. No bond failure between the repair material and the concrete substrate was observed

    throughout  the tests. It was noted that the properties of the repair material affects the behavior of the repaired beams at both service­ability and ultimate limit state.                                                            conclusions obtained from these results  together with some recommendations for further work were presented.