Thermally restrained plate girder loaded in shear at high temperature

Investigations on the buckling and post-buckling behaviour of web plates subjected to shear started since the 1930s to evaluate the post-buckling shear strength of panels used in aircraft structures. However, the post-buckling strength was not directly adopted in the design of plate girders until 1960s. In the area of plate girder research, there is still a lack of experimental works at fire conditions, especially with incorporations of thermal restraints induced by adjacent unheated structures in fires. This paper presents an experimental investigation of twelve simply-supported steel plate girders subjected to shear loading at elevated temperature. In this investigation, three series of steel plate girders (RTG3, RTG4 and RTG5) have been tested at three constant elevated temperature levels, viz. 400, 550 and 670 °C. Additional axial restraints have been applied onto the specimens. The tests were to investigate the shear buckling behavior and the effect of thermal restraint on plate girder panels. Based on test results and observations, the pre- and post-buckling behaviour of plate girder web panels at high temperature will be discussed and compared with analytical and finite element predictions. They will also be compared with experimental results of the same series of specimens but without thermal restraint. The knowledge gained from both the experimental and analytical works will be beneficial to a future study on steel beam-to-column joints at elevated temperatures, due to similar shear failure behaviour observed in the Cardington fire tests.