Vulnerability and improvement of reinforced ECC flexural members under displacement reversals: Experimental investigation and computational analysis

Engineered Cementitious Composite (ECC) is characterized by ductile tensile strain-hardening behavior accompanied by multiple narrow cracks. Its ultimate tensile strain under uniaxial loading is often reported to be more than 3%. This study explores the flexural performance of regular and innovative reinforced ECC members under displacement reversals. Four reinforced cantilever structural beams are prepared and tested under cyclic loading. Among the specimens, two ECC beams are proposed to improve the failure mechanism of regular reinforced ECC beams, which are found to be prone to steel fracture in this study. In one specimen, the flexural rebar is debonded in the potential plastic hinge region. In another specimen, it is flexurally reinforced with Nickel-Titanium shape memory alloy (SMA) rebar with the property of superelasticity. The behaviors of the cantilever beams are evaluated using multiple performance measures, including hysteretic loops, numbers of cracks, beam rotations, and steel strains. In addition to the experimental study, computational models which are capable of simulating the hysteretic behavior of the tested specimens with reasonable accuracy are suggested.