Shear strengthening of fire-damaged reinforced concrete beams using bolted-side plating

Six reinforced concrete (RC) beams were fabricated and exposed to fire in accordance with the international standards ISO834 temperature curve, four of which were retrofitted employing the bolted side-plating (BSP) technique. The shear tests of two control beams and four beams strengthened with BSP after fire were carried out. The influence of the plate depth and bolt spacing on the shear strength, ductility and stiffness was investigated. The testing results indicated that the BSP method can significantly increase the shear capacity of fire damaged RC beams and improve the overall shear and flexural performance. The strengthening effect increases as the increase of plate depth and the decrease of bolt spacing. When the external load is very large, local buckling of steel plate will occur under the combined action of bending and shearing. Both longitudinal and transverse slips coexist on the plate-RC interface of BSP beams. The bolt spacing exerts an important influence on the degree of partial interaction between the plate and the concrete. In the design of BSP reinforcement, the relative relation between the number of anchor bolts and the plate depth should be taken into consideration.