Analysis of fire resistance of portal steel frame structure under different connections

This paper makes finite element analysis of fire resistance under different connections for portal steel frames. Fire protection not apply on the secondary beam, there are two ways of girder-column´s connection to calculate: beam connection, and pin connection. The results of the analysis indicate that the mechanical behavior of steel frames in fire conditions is dominated by the effects of thermal loading, thermal expansion and thermal gradient. The overall deformation of pin connection is larger than it of beam connection, and the stress suffered by beam structure is bigger than pin structure. When the overall beam steel frames´ connection is taken by local pin connection, the stress of structure will reduce, helping to ensure strength and stability of steel structures. The deformation of the girder can be reduced when the beam connection is taken place by pin connection. The conclusion provides a reference for structural engineers on fire resistant design of steel frame.