| In recent years,steel reinforced concrete frameworks has been applied more and more in practical engineering,and its excellent bearing capacity,high stiffness,seismic performance and fire resistance have attracted attention widely.It is very important to study the fire resistance of steel reinforced concrete column-reinforced concrete beam portal frame,which provides a theoretical basis for the fire resistance design and research of steel reinforced concrete column-reinforced concrete beam portal frame.In this paper,fire resistance test of steel concrete frameworks under fire and external load is carried out to analyze the temperature variation characteristics and related mechanical properties of the frame under fire.The main research contents are as follows:1.The fire resistance test of five sections of steel concrete column and reinforced concrete beam portal frameworks was carried out,and the temperature variation characteristics,beam and column displacement variation rules and the failure characteristics of the frame under fire were investigated.Meanwhile,the relevant factors influencing the test results of steel reinforced concrete column-reinforced concrete beam portal frameworks are analyzed.2.Based on the constitutive relationship of different materials under high temperature and the cross-section size of the test frame under fire,the finite element analysis model of the steel concrete portal frameworks under the action of thermodynamic coupling is established.The finite element analysis model is used to verify the test results of the portal frame under fire.The experimental results are in good agreement with the simulation results.3.Based on the finite element analysis model,the temperature distribution,typical failure modes,beam-column deformation characteristics and frame stress distribution at different sections of the steel reinforced concrete column-reinforced concrete beam frame are studied.4.In fact,many building fires occur in frameworks.In order to further explore the influence on the fire resistance of actual frameworks,the fire resistance of multi-storey and multi-span steel concrete portal frameworks is studied by numerical simulation analysis based on the actual building size.The failure characteristics,deformation characteristics and fire resistance limits of multi-storey and multi-span frameworks under fire conditions are studied by finite element analysis model.At the same time,the influence on the fire resistance limits of multi-storey and multi-span frameworks under different working conditions is considered.The results show that:the number of floors,the number of spans and the load ratio have great influence on the fire resistance limits of the frameworks. |
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