Effect of high temperature creep on the fire response of restrained steel beams

At room temperature, and at service load levels, 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 members. Under fire conditions, significant forces develop in restrained steel beams and these forces induce high stresses in the steel section. The extent of creep deformations is affected by magnitude and rate of development of stress and temperature in steel. In this paper, the effect of high temperature creep on fire response of restrained beams is investigated. Current high temperature creep models are compared. Finite element model created in ANSYS was validated by comparing the predictions with fire test data. The validated model was applied to investigate the effect of load level, heating rate, fire scenario and fire induced axial restraint on the extent of creep deformations. Results from the parametric study indicate that the influence of high temperature creep increases with the increase in axial restraint, heating rate, and load level. Generally, neglecting high-temperature creep effect stiffens the structural response and leads to reduced deflections but larger restraint forces. Therefore, neglecting high temperature creep in fire resistance analysis of steel structures can lead to unconservative predictions.