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

Abstract

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 <i>A</i>_b to the bearing plate area <i>A</i>_l (local area aspect ratio <i>A</i>_b/<i>A</i>_l)_, the ratio of core area <i>A</i>_cor to the bearing plate area <i>A</i>_l (core area aspect ratio <i>A</i>_cor/<i>A</i>_l,)_, and the reinforcement ratio <i>p</i>_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 <i>p</i>_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 <i>A</i>_cor/<i>A</i>_l was not obvious. In addition, decreasing the <i>A</i>_b/<i>A</i>_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.