COMPUTATIONAL MODEL OF NUMERICAL ANALYSIS OF PRE-STRESSED STEEL STRUCTURE WITH SEMI-RIGID CONNECTION IN FIRE

摘要

The computational model of numerical analysis of fire response of the pre-stressed steel structure with semi-rigid connection subjected to fire load is established based on the previous work for analysis of the structures at ambient temperature, according to the main consideration of the response mechanism of the structure in fire. The model provides the convenience that the cables with higher tensile strength used in the structures can be set arbitrarily and stretched for more times. For the convenience of application, the EC3 constitutive model of the steel materials in fire is simplified with series expansion, and the suggested formula for each stage are unified. It is specially denoted that the computational model presented here for analysis of the structure with semi-rigid connection subjected to fire load is established based on the key consideration that all response of the structure in fire is due to two reasons, one is that the temperature internal forces are produced in the structure and the other is that the material property of the structural elements varied with variation of fire temperature. For simplification of the computational model of fire behaviour of the steel structure under fire, the variation of connection stiffness with fire temperature is not considered too. The final response of the steel structure with semi-rigid connection under fire consists of the two response results caused from the two reasons presented above through solving two equations, respectively. It is shown that the method presented here for establishing the computational model of the steel structure under fire has advantages of having clear and definite meaning, being convenient for establishing the computational model and having better suitability.