Experimental and Numerical Analysis of Prestressed Prefabricated Self-Centering IMS Composite Frame Joints

Full-scale model tests of three integral prestressed prefabricated frame structure system (IMS) prestressed friction joint specimens under low cyclic loading were conducted to explore the factors influencing the hysteretic behavior of a new joint. The use of a high-strength grouting material (steel fiber) for joints was found to delay the damage of the grouting material under repeated loads and cause reduction of effective prestress. Additionally, replacing the prestressed reinforcement with unbonded prestresssed reinforcement in the precast column and the open channel near the column maximized the deformation capacity of the structure and reduced the structural damage and stiffness degradation in later stages. With an increase in the length of the unbonded section, the peak load of the specimen decreased and the energy consumption was worsened. To enhance the energy consumption of the joint, this study proposes a hybrid connection joint between the energy-consuming and prestressed reinforcements in the open slot. Using ABAQUS numerical modeling and analysis, the joint structure was further optimized and the variations in the energy consumption capacity of the hybrid joint with the position of the prestressed reinforcement, the proportions for the local weakening of energy-dissipating reinforcement, and the bonding mode were obtained. The numerical results demonstrated that the seismic performance index of the hybrid joint was comparable to or even higher than that of the cast-in-situ joint and indicated excellent self-centering and damage recover capacity.