AXIAL COMPRESSION PERFORMANCE OF CONCRETE COLUMNS STRENGTHENED BY STEEL BAR AND WIRE MESH MORTAR

In order to increase the strengthening efficiency, a new method to strengthen concrete columns with steel bar and wire mesh mortar is proposed here. A total of 36 circular concrete columns were strengthened, using steel bar and wire mesh (SW), steel bar (S), sole fiber reinforced polymer (FRP) and hybrid fiber reinforced polymer (HFRP) respectively. Experimental study was performed under axial compression to investigate the influence of the different strengthening methods on the load carrying capacity and ductility. The experiment results showed that, the peeling of the mortar cover and the crushing of the core concrete happened almost simultaneously for the SW strengthened columns. The mortar cover crack spacing was basically equal to the wire mesh spacing, leading to the occurrence of many small cracks. As a result, on the premise that the ultimate load of the SW columns increased 30% compared with the S columns, the ductility of the SW columns was still about twice as that of the S columns. Although the increase of the load bearing capacities of FRP or HFRP strengthened columns was higher than that of SW or S strengthened columns, the ductility and deformation capacity of FRP or HFRP strengthened columns were obviously lower than those of SW columns. The formula of the ultimate load of SW mortar strengthened concrete columns was then proposed.