Experimental Investigation of Concrete Beams Strengthened with Embedded Through-Section Steel and FRP Bars

This paper presents an experimental investigation on reinforced concrete (RC) beams strengthened in shear with embedded through-section (ETS) steel and fiber reinforced polymer (FRP) bars anchored with and without a mechanical anchorage system. The responses of the beams, including the load-deflection relationship, crack patterns, modes of failure, and reinforcement strain, are discussed. In addition, the shear performances of different strengthening systems are analyzed by comparing the ETS cases with ordinary reinforcement techniques. The effects of different types of ETS strengthening are considered in the presence of varying numbers of steel stirrups. An investigation of the shear contribution of the strengthening bars is carried out to assess the applicability of existing models. An average strain equation for ETS-FRP bars is developed from original models. Comparisons of the results obtained from this paper with those reported in the literature demonstrate that the end anchored ETS strengthening system provides a significant improvement in the shear strengthening efficiency. Furthermore, the truss analogy combined with the developed average strain formulation is an effective method to predict the shear resisting force of anchored ETS-FRP bars in ETS-FRP strengthened beams.