Strengthening of shear damaged RC beams with external clamping

Strengthening or retrofitting of existing reinforced concrete bridges has become an important issue for the bridge engineers due to the rapid increase of both volume and weight of the traffic during recent years. External post-tensioning is considered as one of the most appropriate techniques for strengthening and rehabilitation of the existing reinforced concrete bridges. While the external post tensioning could be effectively used for the flexural strengthening of existing bridges, recent studies shows the efficiency of the shear strengthening using external post tensioning is significantly reduced by the existing shear cracks. The effect of the existing shear crack is a complex function depends on a number of parameters including width of the crack and crack inclination. Due to the inclination of the shear cracks, the conventional external post tension-ing may not effectively close up the cracks. Larger crack width leads to a significant reduction in the aggre-gate interlocking, which may cause a drop in the strengthening efficiency. Therefore, it is important to inves-tigate possible techniques to reduce the effect of the existing shear cracks in RC bridges. An attempt was made to investigate the efficiency of the external clamping to reduce the effect of the existing shear cracks. Six reinforced concrete beams were tested with static four-point loading with external clamping with different orientations to enhance the capacity. The experimental result shows that the orientations of the clamping sig-nificantly influence the capacity of the beams, which is discussed in this paper.