| In the assembled building structures,the node area is the hub of the structural force,which is a key part in the assembled structure.Under fire,the assembled steel node is long-term,and the steel can be weak,so that the load capacity of the node is lowered,and the node is destroyed.Due to the difference in connection form of the assembled node and the traditional welded steel node,its destructive site and the destruction form also have a significant difference.This paper has studied the impact of new assembled steel crowd fire resistance and improved node protection form on fire performance of assembled nodes,and proposes a reasonable recommendation for improving steel corrosion refractory protection.In this paper,there is a modified assembly steel burning fire test in 6 groups of ASTM-E119 heating mode,and the temperature distribution,node deformation,damage form,and fire resistance limit of steel beef leg nodes are obtained;the node is analyzed by establishing finite element model analysis nodes in high temperature The anti-fire performance and damage mode,the main research contents and conclusions of the paper are summarized as follows:1.For 3 groups of stainless steel bolts,no protective sleeve for welds,the heating test was carried out.The results show that it can effectively improve the fire limits of nodes with stainless steel bolts and increased welds.When the node is destroyed,the stainless steel bolt is used to extend the refractory limit of the normal bolt node,and the stainless steel bolts have no obvious deformation;the node is welded to the nodes,the nodes,the node refractory limit prolongs 23 min.The destruction of the node is deformized sharply and exhibits a certain brittle feature.The two sets of nodes to add welds are basically the same,and the fire limits of the nodes are determined by the weld expiration time.2.For 3 groups of nodes with protective sleeves were carried out.The results show that the protective housing can effectively improve the fire limits of nodes.The weak links of the cattle leg are mainly ribs,bolts and side panels.Refracturing protection of the upper ribs and ribs of the node,the refractory limit of the node is approximately 107 min;protect the ribs,ketiles and side plates of the node,and the fire resistance can reach 150 min.It can also significantly increase the fire resistance of nodes in the node surface,and the fire resistance limit of the test node is 120 min.3.The finite element model of node fire performance analysis was established using Abaqus software,and the rationality of the model was verified by the comparison of the temperature field,the deformation curve and the test results.The simulation curve and the test curve trend are basically consistent in the temperature field.Due to the heat consumption during the test,the test temperature is slightly lower than the analog temperature;in the mechanical analysis,the simulation results of the node are in good agreement with the test results,and the simulation curve begins to appear.The time node to the displacement deformation is consistent with the test curve,and the test deformation is slightly greater than the simulation result.4.The effects of rib thickness,eccentricity,and load on nodes were analyzed.The results show that the fire limits of the steel rage nodes under fire increases with the increase in the thickness of the rib,and decreases with the reduction of the load,and decreases with the load. |
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