Seismic retrofit of precast RC walls by externally bonded CFRP composites

Abstract

This work pertains to the field of earthquake engineering and addresses the seismic behaviour of the reinforced concrete walls. The objectives of the thesis are to investigate the seismic performance of the precast reinforced concrete walls, assess the weakening effects caused by doorway cut-outs and reveal the effects of the seismic retrofit by externally bonded carbon fibre reinforced polymers. The experimental program consisted in seven quasi-static cyclic tests on near-full scale precast reinforced concrete wall specimens. Particular care was paid to the design of the test set-up and loading procedure in order to model the outrigger effect which stimulates shear behaviour instead of the flexural one. The experimental variables referred to the opening and the strengthening condition. The influence of the cut-out opening size on the shear strength, stiffness and energy dissipation rate was considerable. The retrofitting technique by means of CFRPEBR yielded improved behaviour characteristics, primarily in terms of energy dissipation; however, certain limitations were identified on the use of this strengthening system in reversed cyclic applications. In addition, the test results showed that by considering the outrigger effect the cyclic response and the failure mode of the shear walls is governed by diagonal compression. This imply a different look on the seismic design and analysis of the reinforced concrete wall structures.