Research on seismic performance of coal gangue aggregate concrete beam–column joints

To evaluate the seismic performance of coal gangue concrete (CGC) beam–column joints, this study conducted cyclic loading tests on five CGC joints and one normal aggregate concrete (NAC) joint. The effects of coal gangue replacement rate and longitudinal reinforcement ratio of the beams on the seismic performance of the joints were investigated. The experimental results showed that the failure modes of the joints can be primarily categorized into flexural failure of the beam ends and shear failure in the joint core. Compared to the NAC joint, the damage to CGC joints was more severe. As the coal gangue replacement rate increased, the joints exhibited a pronounced pinching effect in the hysteresis curves, accompanied by accelerated stiffness degradation and diminished energy dissipation capacity. In addition, increasing the longitudinal reinforcement ratio significantly reduced concrete damage at the beam ends and enhanced the bearing capacity. However, an excessively high reinforcement ratio led to shear failure of the joints, reducing the ductility.