Efficient and Low Invasive Strengthening of Existing Concrete Structures in Shear

Three different low invasive shear strengthening techniques have been investigated in a number of structural tests with RC members subject to shear loading, namely post-installed reinforcing bars, a specifically designed anchor system and CFRP sheets. The post-installed rebars are inserted into inclined pre-drilled and mortar- injected holes from the bottom side of a concrete member and anchored with metal plates at the accessible bar end. The sleeved undercut anchor, on the other hand, is set vertically into the pre-drilled hole and the load is then introduced via a self-undercutting expansion sleeve. The third tested system consists of CFRP sheets and special end anchorages, introducing the load of the CFRP tension chords to the compression zone of the beam. All three strengthening methods can be installed from the soffit of a structure without significant disturbance of the traffic and without major interventions affecting the existing cross section of the structure. Significant load gains have been reached in the performed structural tests with each strengthening technique.