Local web buckling of double-coped steel beam connections

Abstract

This paper presents a comprehensive study on local web buckling behaviour of double-coped steel beam connections, cases which are common when beams of similar heights are joined. The study commenced with a series of full-scale tests on 11 specimens, covering a spectrum of cope lengths and cope depths. Local web buckling was observed as the main failure mode for most specimens. The ultimate load was found to decrease with increasing coped length and cope depth, and in addition, an increase of the rotational stiffness of the beam end connection could benefit the local web buckling capacity. A numerical study was subsequently performed enabling further interpretation of the test results. Good agreements were observed between the test results and finite element analysis predictions, and the stress conditions within the coped web panel at different loading stages were fully revealed. The numerical study also showed that the ultimate loads of some models were not sensitive to initial imperfection amplitudes, especially when the cope length was large (i.e. 450 mm or longer). It was believed that the imperfection insensitivity characteristic was due to the presence of post-buckling mechanism. Summarising the available test data, including the current test results and those previously reported by other researchers, design comments were made through comparisons against the existing design method. Conservative test-to-predicted ratios were generally shown, but unsafe predictions were obtained for some cases. A modification to the existing design approach was finally proposed for safer design of such connections.