Paper number 1061

DISCUSSION ON THE FAILURE MECHANISM OF RC BEAMS STRENTHENED IN SHEAR BY EXTERNALLY BONDED CFRP SHEETS

A. Li, T. Assih, and Y. Delmas

Laboratory of Mechanics, Materials and Structures
University of Reims Champagne Ardennes
Rue des Crayères , BP 1035
5 I68 7 Reims Cedex 2, French

Summary

The technique of strengthening or repairing reinforced concrete (RC) structures with externally bonded steel plates or composite sheets have been successfully applied in civil engineering. The RC structure is often strengthened in flexure. In this work, the authors study the failure mechanism of the shear strengthening of RC beams. Five types of beam with different dimension of strengthening composite fibre reinforced plastic (CFRP) sheets were used. . The appearance of the initial cracks, the crack propagation in the structure up to the ruin was monitored and discussed In particular, for one of the strengthened RC beams, the failure mode and the failure mechanism are fully analysed. The experimental results show that the crack modes were greatly influenced by the dimension and the position of the strengthened CFRP sheet. The crack began always in flexure. The first cracks were found to be in concrete at the tensile region and at the beam centre The appearance of the cracks in the RC beam extremity is very late.

Keywords

strengthening, beam, carbon fibres, crack, bending, failure.