| Steel as an important structure,with its light weight,plastic,manufacturing is simple,short construction period,etc.,it is widely used.At the same time,due to the large steel thermal conductivity,heat capacity is larger than the smaller coefficient of thermal expansion and other reasons leading to its fire resistance is poor,resulting in steel building indoor fire causing huge losses of property cases are not uncommon.The steel beam-column joints as an important part of the Steel Structure for the next node to fire analysis and fire protection force performance is particularly important.Based on the above point of view,the focus of this paper to study fire performance for steel framework beam bolted and welded mixed node,including the following:1.Standard fire heating curve and mechanical properties of steel at high temperature were analyzed.2.By finite element analysis software ANSYS,combined with relevant bolted and welded steel beam-column node FIRE RESISTANCE test finite element model,finite element analysis and experimental results are compared to determine the accuracy of the node model.3.Establish with stiffener and stiffener is no model to analyze the presence of stiffeners for fire resistance performance bolt welded beam-column node impact.4.In the same model under different load case,analyze what changes node fire resistance performance.Some of the above study,the main draw the following conclusions:1.Come standard fire heating curve with the plus temperature stiffeners and without stiffener beams bolted and welded nodes-time curve and temperature distribution and stress distribution.2.In certain conditions,the heating curve obtained node key areas,as the temperature rises,the heating rate of beam-column joints in different regions vary,column web and flange temperature is always higher than the beam web and flange and the end plate.After more than 600 s,column web temperature can reach 500 ℃,warming fast,while the strength of steel is rapidly declining.When the temperature reaches 400 ℃,beam-column joints angle begins to increase rapidly,and its value in the temperature was raised to 500 ℃ reached 0.01,and a linear upward trend,indicating that Node has basically lost the carrying capacity of beam-column joints has become near destruction.Column web and flanges of the beam-column joints as the largest part of the temperature and stress the need to take certain measures in the design and construction were strengthened.3.Stiffener presence can improve the temperature distribution and the stress distribution in beam-column joints,thus improving the fire resistance performance of beam-column joints play a certain role.4.Decreased significantly corner fitting curve,the load will increase fire resistance of beam-column joints-get bolted and welded beam-column node different temperature conditions-rotation curves and bending moments. |
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