A Novel Beam–Column Component Macromodel for the Degradation Mechanism Analysis of RC Structures Subjected to Blast Loading

The traditional fiber beam model has been extensively used to simulate the dynamic behavior of components and analyze the progressive collapse resistance performance of building structures. However, this model overlooks the shear damage and force degradation of beam–column components under explosion loads, necessitating improvements for enhanced accuracy. This paper proposes a new macromodel for components that incorporates force degradation and shear damage based on the traditional fiber beam model for analyzing reinforced concrete (RC) components and structures subjected to explosion loads. The model defines the moment-rotation relationship of nonlinear spring elements using modified compression field theory and calculates the length of the plastic hinge zone of members. The force degradation in the plastic hinge zone is derived from the stress–strain relationship of concrete and reinforced bar materials, simulating the degradation mechanism under explosion loads. The proposed component model has been compared with test results, demonstrating that it is more accurate than the traditional fiber beam model, particularly when RC members undergo severe shear failure due to explosion loads. Additionally, the proposed model significantly reduces computational time in the dynamic behavior analysis and collapse process of RC structures compared to refined numerical models.