Seismic retrofit of reinforced concrete short columns by CFRP materials

Nowadays, reinforcing buildings or bridges against earthquake damage is a real technico-economic challenge. Composite materials applied by the wet lay-up method have been the main reinforcement technology for civil engineering structures since the 1990s. The research developed in this paper concerns seismic reinforcement. The main objectives are to evaluate CFRP’s contribution to mechanical and energetic performance and to the modification of the cracking pattern on short columns. During earthquakes, short columns undergo shear stress due to their low resistance to high imposed horizontal displacements. Eight short columns were tested; their longitudinal reinforcement was higher than the Eurocode 8 upper limit whereas transverse reinforcement was insufficient, in order to ensure shear failure. Seven were continuously or discontinuously reinforced by CFRP or GFRP. They were tested under a constant compression load combined with a horizontal quasi-static cyclic load. It was therefore possible to evaluate the efficiency of such reinforcement by measuring the gain in terms of load and ductility.