Experiment study on seismic behavior of squat UHPC shear walls subjected to tension-shear combined cyclic load

Abstract

Five squat UHPC shear walls with high axial tension ratio ranging from 0.5 to 0.6 were tested under tension-shear combined cyclic load to replicate seismic performance of bottom shear walls in high-rise buildings. All specimens exhibited shear-sliding failure mode characterized by multiple shear-related cracks distributed in a dense array and full-length localization of horizontal crack along the end of anchorage rebars. The seismic behaviors were comprehensively evaluated by hysteretic responses, energy dissipation capacity, strength and stiffness degradation. Additionally, detailed analysis on the strain development of vertical reinforcement and web horizontal rebars were carried out to study their shear resistance contribution. It was found that, with the assistance of steel fibers providing an efficient shear resistance consistent with the varying direction of principal tensile stress, the shear capacity of UHPC shear wall was slightly improved even when axial tension ratio increased to 0.6. The ultimate drift capacity of UHPC specimens reached 3.3% drift with an excellent strength retention ability of more than 500kN in this test. Besides, the accumulated energy consumption of UHPC specimen after crack localization improved by 38% compared with the normal concrete shear wall. Results of strain analysis demonstrated that vertical reinforcement provided an effective clamping force in the shear-sliding resistance. A modified design formula considering efficient tension resistance offered by UHPC was proposed with adequate safety concerns and accuracy.