Experimental and numerical study on the seismic and shear performance of PSRC beam-column joints

To investigate the seismic and shear performance of prestressed H-shaped steel reinforced concrete beam-crossshaped steel reinforced concrete column joint (PSRCJ), a comparative experimental study was conducted through quasi-static tests on two specimens: one PSRCJ specimen and one conventional H-shaped steel reinforced concrete beam-cross-shaped steel reinforced concrete column joint (SRCJ) as a control specimen. The investigation encompassed a systematic analysis of crack propagation patterns, failure modes, hysteretic behavior, load-bearing capacity, energy dissipation capacity, ductility performance, strength degradation, and stiffness deterioration. The results showed that the number of cracks in the upper part of the beam of specimen PSRCJ was significantly less than that in the lower part. The failure modes demonstrated notable differences, with the specimen SRCJ exhibiting typical shear failure in the core area, while the specimen PSRCJ manifested a combined failure mechanism characterized by initial flexural failure at the beam end followed by subsequent shear failure in the core area. Both specimens exhibited an overall anti-S-shaped hysteresis curve with certain pinching effects, with the hysteresis curve of the specimen PSRCJ being fuller. The application of prestress demonstrated significant structural enhancements, including improved stiffness, increased load-carrying capacity, and enhanced ductility, thereby effectively delaying structural damage initiation and progression. Furthermore, a finite element method (FEM) analytical model was developed to investigate the influence of critical parameters, particularly the axial force ratio and prestressing level, on joint shear performance. Parametric analysis revealed an inverse relationship between bearing capacity and axial force ratio, while demonstrating a positive correlation with prestressing level. Based on the experimental and numerical findings, a theoretical formula for predicting the shear strength of joint core area was proposed, which showed excellent agreement with both experimental measurements and simulation results, validating its reliability and accuracy.