Numerical studies on large deflection behaviour of axially restrained corrugated web steel beams at elevated temperatures

• Catenary action of restrained corrugated web steel beams (CWSB) in fire was studied.
• Differences in behaviours of a restrained CWSB and flat web steel beam were presented.
• Load ratio, axial restraint and span-depth ratio affects catenary action greatly.
• Shape of corrugation has very little influences on catenary action.

The large deflection behaviours of axially restrained corrugated web steel beam (CWSB) at elevated temperatures were investigated using a finite element method. The web of studied CWSB adopted commonly used trapezoidal shape. The applicability of finite element model presented was validated against test results on the restrained flat web steel beam (FWSB) in a fire. Studied parameters of CWSB included the load ratio, the axial restraint stiffness ratio, the span-depth ratio, the corrugation shape of the web, the web thickness and the flange thickness. The evolutions of the vertical deflection, the axial force and the bending moment at mid-span of the CWSB with the elevated temperatures were presented. For the axial stiffness of a CWSB was smaller than that of a FWSB with the same dimension, the compressive force due to the restrained thermal elongation in a CWSB at elevated temperatures was lower than that in a FWSB. In addition, the CWSB went into the catenary action phase at a lower temperature compared with the FWSB with the same load and axial restraint stiffness ratio. The corrugation shape and the thickness of the web had very little influences on the catenary action behaviour of the restrained CWSB at elevated temperatures. Parameters that greatly affected behaviours of CWSB at elevated temperatures were the load ratio, the axial restraint stiffness ratio, and the span-depth ratio. With the increase in load ratio, the temperature at which the restrained CWSB went into catenary action phase decreased. The axial restraint stiffness and the span-depth ratio did not affect the temperature at which the restrained CWSB went into catenary action phase. However, with the increase in the axial restraint stiffness, the maximum axial force that the CWSB experienced increased and the temperature at which the maximum axial force was reached decreased. With the increase in the span-depth ratio, the maximum axial force the CWSB experienced and the temperature at which the maximum axial force was reached decreased.