| The research of fire resistance on structure includes two main aspects: load capacity and deformation. Destroy of steel columns, which is an important bearing component of structure, will cause structural collapse, casualties and property loss. At room temperature, creep has little effect on the performance of steel structures. However, under fire conditions, creep becomes a dominant factor and influences fire resistance of steel structure. Comparing with the normal steel, high strength steel has higher yield strength and ultimate strength, thus can effectively reduce the sectional dimension, steel consumption, welding workload and project cost. Current design rules on fire resistance of steel structures are primarily based on the experimental results from normal steel columns and have not account for the effect of high temperature creep.In this paper, the effect of high temperature creep on fire response of steel columns is investigated. Finite element model established in ANSYS was validated by comparing the predictions with fire test data. It is shown that high temperature creep makes steel columns into plasticity in advance, and the results of finite element model considering creep have good agreement with the test results. Therefore, neglecting high temperature creep in fire resistance analysis of steel structures can lead to un-conservative predictions.The validated finite element model was used to carry out a set of parametric studies on normal steel columns and high strength Q460 steel columns. The critical temperature and stability factor of steel columns were compared with the results of fire resistance design code. The results from parametric studies indicate that the slenderness ratio, load ratio, heating rate, initial imperfection and bending direction have significant influence on the behavior of steel columns considering creep effect under fire conditions. However, the sectional dimentions and yield strength of normal steel columns have little influence. The fire resistance of high strength Q460 steel columns is better than that of normal steel columns, and the results given in the code for fire safety design of steel structures in buidings-CECS 200:2006 are not applicable to high strength Q460 steel columns. Based on theoretical and parametric analysis, a method is proposed to calculate the bearing capacity of steel columns considering the effect of high temperature creep.The innovation of this paper can be listed as follows: 1. The effect of high temperature creep on fire response of normal steel columns is investigated. 2. The load capacity and deformation of high strength Q460 steel columns considering creep effect or not is investigated in fire. 3. A method is proposed to calculate the bearing capacity of normal steel columns considering creep effect. |
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