A Refined Multi-Spring Model for Prestressed Precast Concrete Connections

Precast concrete with a moment-resisting frame with hybrid beam–column connections (HBC), which is featured by inelastic deformation induced by opening and closing of the interface between precast beam and column, has been emphasized in recent years. Precast concrete frame structures with HBC are difficult to simulate because current numerical models usually adopt multiple elements to simulate contact surfaces, resulting in complexity, low computational efficiency, and a difficult modeling process. To explore the opening and closing behavior of the interface of the hybrid beam–column connection, a refined multi-spring model (MSM) with only two gap elements whose position and capacity is determined by a simple advanced section analysis method is proposed. The proposed multi-spring model, which is obviously with high computational efficiency, is able to tracking accurately the change in compressive zone height of the interface between precast beam and column and count in “beam elongation effects”. The proposed model was employed to simulate four prestressed precast beam–column connections. The accuracy of the analytical model was validated by examining three aspects: global mechanical performance, stress in prestressed tendons, and compression zone depth.