Influence Of Different Fire Boundary On Fire-resistance Of Precast Column Composite Beam Integral Frame Joints

Prefabricated concrete structure,not only can greatly shorten the project cycle,but also has the advantages of high efficiency,cost saving and environmental protection,which conforms to the development direction of modern green building.Node is the key position of the structure,and its fire resistance performance can determine whether the structure is safe or not.Most of the existing researches on the fire resistance performance of the fabricated joints are focused on the situation of fire on four sides,but in the actual fire,because of the fire on different floors,the fabricated joints may also be in the state of non-uniform fire,such as the upper part of the joint or the lower part of the joint.The change of fire mode not only affects the distribution of temperature field,but also changes the mechanical performance of the joint.Therefore,it is necessary to study the fire-resistant performance of different fire-resistant assembly joints.In this paper,the experimental research and finite element analysis are carried out for the fabricated joints with different fire boundary.The main research contents are as follows:(1)The fire resistance tests of two prefabricated middle joints and two prefabricated side joints were carried out under the standard ISO-834 temperature rise conditions.The fire resistance tests of two different types of joints were carried out on the upper part and the lower part respectively.The section temperature and the deformation of beam column during the whole process of temperature rise were measured.The failure mode and the fire resistance pole of the joint under different fire rise modes were obtained Limit.(2)Based on the finite element analysis software ABAQUS,the finite element analysis models of the assembled middle node and the assembled side node under different fire boundaries are established.The temperature field distribution,beam column deformation,failure mode and fire resistance limit of the joint section are analyzed by the way of thermo mechanical coupling,and the results are compared with the test results.(3)The fire resistance parameters of middle and side joints with different fire boundary are analyzed.The influence of reinforcement ratio,load ratio,beam column linear stiffness ratio on the fire resistance of joints is studied.The fire resistance limit of joints with different parameters is obtained.