Application of engineered cementitious composites in the plastic hinge of reinforced concrete beams for seismic enhancing

Abstract

AbstractShear failure of the potential plastic hinge region of reinforced concrete (RC) beam usually causes irrational failure mechanism and low seismic response of the whole frame structure. In this study, engineered cementitious composite (ECC) was proposed to apply locally in the potential plastic hinge region of RC beams to improve the failure mode and rotation capacity of the members. One RC beam and five ECC‐RC composite beams were manufactured, and tested by lateral cyclic loading. The test variables were the length of ECC strengthening region, stirrup ratio and longitudinal reinforcement ratio. The test results indicated that the plastic hinge region of the RC beam failed in shear with poor plastic deformation and low energy dissipation. For the ECC strengthened beams, flexural behavior dominated the ECC region and shear failure was migrated up into the concrete region or eliminated. The ECC region of the composite beams exhibited great rotation capacity, thus the hysteretic response, plastic deformability and energy dissipation of the ECC strengthened beams were improved significantly. Meanwhile, applying ECC in the plastic hinge effectively enhances the damage tolerance of the beams. Based on the test results, the substituting length of ECC in the potential plastic hinge of the RC beam is recommended to be no less than the beam height. Besides, the strength of ECC strengthened beam can be calculated and checked by the current design codes.