Behaviour of column web component of steel beam-to-column joints at elevated temperatures

This paper presents an experimental investigation on stocky column web panels of semi-rigid beam-to-column joints exposed to fire conditions in order to verify an analytical prediction model. Recent experimental studies show that the degradation of material properties and high axial forces, due to restrained thermal expansion of beams at elevated temperatures, significantly affect the moment-rotation response of the joints. The component method originally established for the evaluation of the joint behaviour at ambient conditions can be adopted for elevated-temperature cases. Recently developed mechanical models for joints may not be accurate as the column web component is simultaneously subjected to bending moments and axial forces. This paper focuses on the component column web in shear in order to identify the key parameters which affect joint behaviour in shear at elevated temperatures. This experimental work was conducted on three extended end-plate connections subjected to both ambient and elevated temperature conditions. After validations by test results, detailed finite element simulations were performed for a series of parametric studies at other elevated temperatures. Both experimental and numerical results are finally compared with analytical predictions.