The facts demonstrated in the experiments and the real fire hazards showed that the restrained steel beams have better fire-resistant capability than the simply-supported beams.Under the effect of the restraints

beams in fire condition can undergo very large deflection and the sudden crash can be avoided.In addition

the axial force will be induced and play an important role in the behaviour of the restrained beams.The factors influncing the behavior of restrained beams subjected to fire include the loads on the beam

the stiffness of axial and rotational restraints and the temperature distribution in the cross-section of beam

etc.Based on the assumptions made regarding the deflection curve of beam according to the restraints and the load type

the axial force and the strain and stress distributions in the beam can be determined.By integrating the stresses

the combined moment and force in the cross-section of the beam can be obtained.Then

through subtituting the moment and axial force into the equilibrium equation

the behavior of the restrained beams in fire can be worked out.In addition

for the safety estimation and repairing after a fire

the behaviour of restrained beams subjected to temperature descending needs studying.For the restrained beams experiencing very high temperatures

the strength of steel will recover when temperature descends

but the contract force will aggravate the stress in the beam

especially at the end.In this paper

the behaviour of the restrained beam in cooling phase is analyzed

and the effect of the contract force is discussed.