Experimental Research On Post-fire Performance Of Prefabricated Concrete Frame Structure Beam-column Interior Joints

With China’s economic and social development and the improvement of building technology,the demand for sustainable development of building products and the demand for environmental protection of construction environment are increasing,which promotes the prefabricated structure to be promoted and applied in China.Precast column-composite beam assembly integral reinforced concrete frame structure is one of the main forms of precast structure.At present,many scholars have carried out some researches on the form and connection structure of assembly-type joints,the bearing capacity and seismic performance at room temperature,and the performance at fire and high temperature.However,as the foundation and basis for structural damage assessment and reinforcement after high temperature,there are few reports on prefabricated joints after fire.Based on the above situation,this paper conducts an experimental study on the mechanical properties of joints after fire in the integrated frame of precast column-composite beam assembly,and analyzes the influence of key parameters on the fire resistance of joints through the finite element model.The main research contents and achievements of this paper are as follows:1.The post-fire mechanical properties of two precast frame joints and one cast-in-place frame joints(for comparison of specimens)were tested.The temperature field distribution and deformation of the nodes in the whole process of temperature rise and cooling are obtained.The performance difference between fabricated and cast-in-place joints at high temperature is compared.2.Using ABAQUS software,the finite element analysis model of the node in the assembly of prefabricated column-composite beam was established,and the performance of the node during the whole loading process was simulated after constant load rise and fall with moderate and high temperature,and the node temperature,beam end and column top displacement and failure pattern of the node were analyzed.The correctness of the model is verified by comparing with the measured results.3.By using the verified model,this paper analyzes the influence of main influencing parameters such as reinforcement ratio,beam-column line stiffness,load ratio and heating time on the node performance,including the temperature change of the node,beam-column displacement change,failure shape of the node in different stages and the change rule of the residual bearing capacity after fire.