Experiment and Validation of Local Bearing Capacity for Ultra-High-Performance Concrete Confined with Stirrups

Ultra-high-performance concrete (UHPC) has the advantages of high compressive and tensile strength, high bending strength, good durability, remarkable corrosion resistance, and low self-weight. In this study, ten UHPC specimens were designed based on three fundamental parameters, including the ratio of the gross supporting area A_b to the bearing plate area A_l (local area aspect ratio A_b/A_l)_, the ratio of core area A_cor to the bearing plate area A_l (core area aspect ratio A_cor/A_l,)_, and the reinforcement ratio p_v, to investigate mechanical behaviors and bearing capacity. Failure modes, cracking load, crack propagation, wedge features, the relationship between local compression and deformation, and the local bearing capacity was investigated. Finite element models (FEMs) were built to simulate and validate the observed behavior of the anchorage zone under compressive loading. The experiment results demonstrate that the p_v significantly increases the bearing capacity. When the reinforcement ratio increased from 4.5% to 3.7%, the bearing capacity increased by 23%, and the effect of A_cor/A_l was not obvious. In addition, decreasing the A_b/A_l from 11.1 to 6.3 increases the bearing capacity to 19%. Furthermore, a model was proposed to predict the bearing capacity of the UHPC specimens reinforced with stirrups. The calculated values, numerical predictions, and experiment results showed good agreement.