| Corrugated steel web composite frame is an innovative structural form,which is widely used in long-span,heavy-duty cold storage and industrial buildings.The engineering practice shows that the composite frame with corrugated steel webs has good bearing capacity,stiffness and economy.At present,scholars have carried out in-depth research on the bearing capacity and seismic performance of corrugated steel web structures at room temperature.However,the failure mechanism and fire resistance of corrugated steel web structures at high temperature are not clear,and there is a lack of necessary understanding of their fire resistance.As the most critical part of the frame,the fire resistance of joints is particularly important.Therefore,it is of great practical value to study the fire resistance of corrugated steel web composite frame joints.Based on the above situation,this paper studied the fire resistance performance and fire resistance design method of edge joints of corrugated steel web composite frames,and revealed the failure process and mechanism of edge joints of corrugated steel web composite frames under fire.The main research contents and results are as follows:(1)The constitutive models of concrete and steel at room temperature and high temperature were selected,and the thermal mechanical coupling analysis model of corrugated steel web frame edge joints was established by using ABAQUS finite element software.The rationality of the finite element model was verified by using the existing test data.(2)Through the finite element analysis of typical frame edge joints,the distribution law of temperature field,the failure mode of joints,the change law of displacement time curve of beams and columns,and the change law of joint stress-strain distribution under the constant load heating mode were studied,and the failure mechanism of joints was revealed.(3)The influence of the main parameters on the fire resistance of the edge joints of the corrugated steel web frame was analyzed.The parameters include: load ratio at the beam end,load ratio on the column,the ratio of the longitudinal reinforcement at the lower part of the beam to the area of the bottom plate,the beam height,the thickness of the column square steel tube,the thickness of the upper and lower flanges of the beam.The results show that the increase of beam load ratio,column load ratio and beam height has a significant effect on the fire resistance of the joint;The increase of the thickness of the column square steel tube will slightly increase the fire resistance limit of the joint;The ratio of the bottom longitudinal bar to the bottom plate area and the thickness of the upper and lower flanges of the beam have little effect on the fire resistance of the joint.(4)The fire resistance protection of corrugated steel web frame edge joints was studied,and the influence of different thickness of fire retardant coatings on the fire resistance of joints was analyzed.Based on parameter analysis,the recommended thickness of fire retardant coating for joint beams and columns was given. |
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