Effect of jacket configuration and anchorage in hybrid strain hardening cementitious composites with steel mesh strengthening of reinforced concrete beams.

Abstract

Reinforced concrete (RC) structures often need shear retrofit due to factors like design deficiencies, aging, or increased loads. This study explores an innovative hybrid retrofit system for RC beams with shear defects, using an external jacket composed of strain-hardening cementitious composites (SHCC) and welded steel mesh (WSM). An experimental program including nine RC beams, involving control, defected, and strengthened specimens, was prepared to assess the effectiveness of many jacket arrangements (one-sided, two-sided, U-wrapped, and fully wrapped) and the influence of mechanical anchorage. In addition, the experimental work was simulated using Abaqus program to replicate the beams' behavior. Experimental findings showed that the shear defect significantly reduced load capacity, stiffness, and energy absorption. All strengthening configurations improved performance, with effectiveness generally increasing from one-sided to full wrapping. Anchorage bolts enhanced load capacity and energy absorption, particularly for partial jackets and U-wraps. Particularly, the fully wrapped configuration restored the beam's ultimate load capacity nearly to the level of the control beam, even without anchorage, and significantly enlarged absorbed energy. The FE model accurately simulated the experimental failure modes, crack patterns, and load-displacement responses, validating its reliability. Full jacketing with anchorage improved the ultimate load capacity by up to 75% compared to unstrengthened beams. Crack propagation was considerably delayed, and average crack widths were reduced by 30-35%. Moreover, the retrofitted beams exhibited a remarkable increase in energy absorption capacity, achieving up to 3.8 times the energy dissipation of the control specimens. These findings clearly demonstrate the necessity and effectiveness of the proposed retrofit system for extending the service life and resilience of RC beams.