Behaviour of Shear Critical RC Beams with Corroded Longitudinal Steel Reinforcement

Abstract

This thesis discusses the results of an experimental program designed to investigate the effect of corrosion on the behaviour of shear critical reinforced concrete (RC) beams. The results of twenty RC beams (ten deep beams and ten slender beams) are described and discussed. The test variables included: corrosion level (2.5%, 5% and 7.5%) and existence of stirrups (beams without stirrups and beams with stirrups). The feasibility of repairing the corroded shear critical RC beams with CFRP laminates was also investigated. Sixteen specimens were corroded using an accelerated corrosion technique whereas four specimens acted as control un-corroded. Following the corrosion phase, all specimens were tested to failure under three point bending. Test results revealed that the corrosion does not adversely affect the behaviour of shear critical RC beams rather it improves their behaviour. It was found that corrosion changed the failure mode of the corroded beams. The control un-corroded deep beams (beams with and without stirrups) failed in shear-compression failure whereas corroded deep beams (beams with and without stirrups) failed by splitting of the compression strut. The control un-corroded slender beams (beams with and without stirrups) failed in diagonal tension failure whereas the corroded slender beams failed in anchorage failure (beams without stirrups) and flexural failure (beams with stirrups). The analysis of the results showed that corrosion changed the load transfer mechanism and the change of failure mode was associated with the mechanism. The load transfer mechanism changed from a combination of beam and arch action in the control un-corroded deep beams to pure arch action in the corroded deep beams. The load transfer mechanism changed from pure beam action in the control un-corroded slender beams to pure arch action in the corroded slender beams. Two strut and tie models are proposed: one for corroded deep beams and one for corroded slender beams. The ultimate loads of the corroded beams were predicted using these struts and tie models and compared with the experimental results. A very good correlation was found between predicted and experimental results.