Numerical Simulation On The Behavior Of Restrained Steel Beams And Parametric Analysis Of Critical Temperature In Fire Conditions

Steel structure has been extensively applied to construction industry due to its advantage properties, but the poor fire resistant capacity is also prominent. Its mechanical properties such as strength and elastic modulus decrease severely in high temperature which is totally different at ambient temperature. When fire occurs, severe damage or global collapse will happen to the steel structure. Therefore, more and more attention is concentrating on steel fire-resistance.Fire resistant design of steel structure is indispensable, steel beams as very important force members in the structure, so the studies of fire resistant capacity of steel beams have important practical significance. When analysis the fire resistance of the steel beams, the boundary constraints surrounding the beams can be replaced with elastic constraints, it is called "Restrained Steel Beams" system. The behavior between restrained Steel beams and simple beam members are fully different due to the presence of the constraints, the process of axial force in fire is classified as4stages. there are three important temperatures, namely yield temperature, critical temperature and extreme temperature of steel beams, which can reflect the the fire resistant capacity of steel beams. this paper presents the numerical results of the behavior of steel beams at elevated temperature. we can determine the criterions and conditions about the yield temperature、critical temperature and extreme temperature of steel beams from these results,further research on the influence of fire resistant capacity with various parameters.Taking into account of above aspects, the main contents of this paper is divided into the following aspects:(1) Calculation of fire resistance of steel beams in domestic and foreign norms andnumerical analysis;(2) The whole process of response and parametric analysis of axial restraint beams in fire, the main parameters are axial restraint stiffness ratio, load ratio, span-depth ratio, the reduction of norms,yield strength, load type distribution and steel types, etc;(3) The whole process of response and parametric analysis of axial and rotational restraint beams in fire, the main parameters are axial restraint stiffness ratio, rotational restraint stiffness ratio,load ratio, span-depth ratio, the reduction of norms, yield strength, load type distribution and steel types, etc;...