Innovative ECC jacketing for retrofitting shear-deficient RC members

Abstract

Engineered Cementitious Composite (ECC) is distinguished from conventional fiber reinforced concrete by its ductile tensile strain-hardening behavior and crack width control ability. This study investigates the performance of ECC jacketing for retrofitting shear-deficient reinforced concrete (RC) members. Six RC cantilever structural beams are prepared, and five of them are retrofitted with jackets. The experimental parameters involve the properties of the jacket, i.e., (1) ECC or mortar as the matrix, (2) presence or absence of steel meshes, and (3) welded wire or bar meshes. The performance of the various schemes of ECC jacketing is evaluated using the test results of the cantilever beams under cyclic loading. In particular, this study explores whether the appealing properties of ECC shown on the material scale can translate into better performance of the ECC jacket on the structural scale. Multiple performance measures of the beams are employed, including damage patterns, hysteretic loops, energy dissipation capacities, rebar strain profiles, shear distortions, and failure modes. The test results show that the ECC jacket without steel meshes is able to improve the cyclic behavior of the original shear-deficient beam considerably. The behavior of the retrofitted beam at the performance level of the ultimate limit state can be further enhanced by reinforcing the ECC jacket with steel meshes. In addition, the multiple performance measures suggest that the ECC jacket with a single layer of bar meshes be the best retrofitting scheme. Based on the test results, both the advantages and disadvantages of the ECC jacketing technique are reported.