Study On The Fire Resistance Behavior Of Assembled Integral Frame Joints Of Prefabricated Column And Composite Beams

Prefabricated structure is one of the most popular forms of building structure in China at present.As the connecting hub of each prefabricated structure,the joint plays a decisive role in the integrity and safety of the assembled structure.However,the performance of assembled joints under fire is still not clear.In this paper,the fire resistance of prefabricated frame edge joints is studied,and the thermal-mechanical coupling finite element model of joints is established by using ABAQUS software,and the influence of main parameters is analyzed.The main research work and results are as follows:?The fire resistance tests of three full-scale prefabricated column-beam assembled integral frame edge joints and one cast-in-situ concrete frame edge joint are carried out.The temperature distribution of the specimen cross-section? time-displacement curve of beam and coloumn?damage form of the test piece and the fire resistance are obtained.The influence load ratio acting on the beam end and linear stiffness ratio of beam to coloumn on the fire resistance of prefabricated edge joints is compared.The results show that:(1)under the design criterion of strong column and weak beam,the failure position of the joint mainly occurs at the end of beam closed to the coloumn under fire.(2)the development of displacement curve at the end of the beam develops slowly and then quickly,leading to a sudden damage of the joint.(3)the cast-in-place edge node is better than the assembled edge joint as a whole,and the fire resistance is greater in the same case.?The thermal-mechanical coupling finite element model of the joint is established by using ABAQUS software,and the temperature field and displacement curve are compared to verify the rationality of the model.?The parameters of the joints are analyzed by using the verified finite element model.The influence of load ratio acting on the beam end?the ratio of longitudinal reinforcement and the ratio of line stiffness of beam to coloumn on fire resistance of prefabricated column-composite beam assembled integral frame edge joint is analyzed.The results show that:(1)with the increase of the load ratio acting on the beam end,the fire resistance of the assembled integral joints decreases.(2)when h > 300 mm,The fire resistance limit of the joint decreases with the increase of the ratio of longitudinal reinforcement.(3)when h ? 400 mm,the fire resistance of the joint decreases with the increase of the ratio of line stiffness of beam to coloumn.