Study on tensile–shear damage of concrete post‐installed threaded rod specimen

Abstract

To address the technical challenge of improving the deformation adaptability and load‐bearing stability of post‐installed threaded rods in concrete structures—especially in scenarios such as retrofitting of existing buildings and precast component connections where flexible force transmission is required—this study focuses on the influence of key factors on the mechanical behavior of post‐installed threaded rod specimen. A total of eight concrete post‐installed threaded rod specimens were designed, and experimental research was conducted to systematically investigate the effects of three key factors: cement mortar pad, loading protocols, and loading angles. The experimental results show that the introduction of the cement mortar pad can effectively increases the bending deformation range of the post‐installed threaded rod, thereby enhancing its overall deformation capacity and ductility—addressing the problem of brittle failure in traditional rigid anchorage. Additionally, loading protocols and angles were found to exert a significant influence on the force–displacement response: under cyclic loading, the specimens exhibited slip‐type hysteresis curves, and the shear bearing capacity decreased moderately due to cumulative slip damage. The failure modes were categorized into two types: tensile failure and shear failure. Based on the experimental data, the finite element models were established to analyze the stress distribution characteristics of the specimens and quantify the impact of different mortar pad thicknesses on mechanical performance. Finally, the novel contribution of this study lies in proposing empirical equations for equivalent shear and tensile forces under various loading angles, which can accurately calculate the yield and ultimate bearing capacities of post‐installed threaded rod specimens. These findings not only fill the gap in current research on the buffer effect of mortar pads in such anchorage systems but also provide a reliable theoretical basis and design reference for engineering applications requiring improved deformation capacity and fatigue resistance of post‐installed threaded rods.