Research on the Judgement Method for Catenary Action of Restrained Steel Beams in Fire

Abstract

Based on fire tests, a parametric numerical simulation on the catenary action of restrained steel beams in fire was performed by the finite element software ABAQUS. It can be known that axial constraint stiffness, rotational constraint stiffness and load ratio are key factors that affect the catenary action in fire. The formation mechanism of catenary action under ISO-834 standard fire was studied; and the judgement method for catenary action in fire was presented. The results show that: (1) when axial constraint stiffness reaches a certain value, the catenary action of restrained steel beams will occur almost at the same time; (2) with the increase of rotational constraint stiffness or load ratio, the catenary action of steel beams will occur earlier; (3) for restrained steel beams under a small load ratio, the catenary action usually occurs in fire when the mid-span deformation reaches 1/15 of the span; but for restrained steel beams under a large load ratio, the catenary action usually occurs when the mid-span deformation reaches 1/18 of the span; (4) for restrained steel beams with a large rotational constraint stiffness, the judgement method for catenary action in fire can still adopt the same method as above, which will be a little conservative.