Research On The Fire Resistance Of Semi-rigid Nonsway Composite Frames

Steel structure has been widely used in the field of construction engineering due to its good seismic performance,short construction period,flexible structure layout and many other advantages.Steel frame structure has also been increasingly used in industrial and civil buildings.In the steel frame,compared with the welded joints with high stiffness and poor toughness,the semi-rigid beam-column joints connected by high-strength bolts are more and more widely used in practical engineering due to their better performance in earthquake disasters.However,the fire resistance of steel structure is generally poor,so the research on the fire resistance of semi-rigid frame has great theoretical and practical significance.In this research,the finite element software ABAQUS is used to simulate the specific frame fire resistance test.According to the principle of heat transfer,the heating process of the frame subjected to fire in the original test was simulated to obtaine the time-varying temperature field distribution,then apply the same load on the structure as the original test,with the application of thermal-mechanical coupling analysis to obtain the calculation results of the fire effect of the frame,then confirmed the feasibility and accuracy of the finite element method by comparing with the original test results.On the basis of ensuring the validity of the modeling method,the commonly used angle steel connection and endplate connection frames are selected as the research object,and the temperature load is applied in accordance with the ISO834 standard heating curve to obtain the deformation development,internal force change and failure mode of the frame under different fire forms.To identify the key factors that affect the bearing capacity of the frame under fire,this thesis analyzed the influence of the significant parameters such as the height of frame column,beam span,column load ratio,beamload ratio and the thickness of the angle steel or endplate on the failure mode and fire resistance of the frame,at the same time,the differences of thermal-mechanical response of the frames with the two different connection forms were compared,so as to provide references for the fire-resistant design of semi-rigid composite frames.