Investigation into structural performance of precast concrete frame beams reinforced with large-diameter, high-strength steel bars

This study introduces a novel precast concrete frame beam reinforced with large-diameter, high-strength steel bars. The investigation aims to address challenges related to poor construction quality and low efficiency, which commonly arise due to complex reinforcement patterns and excessive use of sleeves in assembling precast concrete elements. The research focused on key parameters, such as the diameter of tensile reinforcement bars and the inclusion of additional waist reinforcements. To assess the structural performance, monotonic static loading tests were conducted on two full-scale beam specimens. The study evaluated crucial aspects like load-bearing capacity, stress distribution, and failure mechanisms, through detailed observations of crack propagation and ultimate failure modes during the tests. The numerical models of the frame beam reinforced with large-diameter, high-strength steel bars were established using the finite element software. Additionally, an appropriate material constitutive relationship was identified for accurately simulating the static behavior of the components under investigation. The findings indicate that bending failure predominantly occurs at the fixed end of the frame beam. Specifically, the concrete in the lower flange of the fixed end is subjected to crushing under monotonic static loading. The introduction of additional waist reinforcements does not significantly enhance either the load-bearing capacity or the crack resistance of the specimens. The reinforced bilinear model and the concrete plastic damage model can accurately simulate the mechanical behavior of the precast concrete frame beams reinforced with large-diameter steel bars. This research provides valuable insights into optimizing the structural performance of such specialized precast concrete components.