Blind bolted moment connection to unfilled hollow section columns using extended T-stub with back face support

This paper presents the results of an experimental and analytical study into a new bolted moment connection between unfilled hollow section columns and open section beams, referred to herein as the extended T-stub connection with back face support. The connection is comprised of T-stubs connecting the top and bottom flanges of the beam to the face of the column and channels connecting the T-stubs to a backplate at the back face of the hollow section column. The addition of the channels to a standard T-stub connection helps to distribute the beam flange tension load to the back face of the hollow section column thus reducing demand on the flexible column face which often will compromise the stiffness of the connection. The extended T-stub connection with back face support was found to be comparable to a previously tested side connection and is much stiffer than a typical face connection. Comparison of the test results and three dimensional finite element (FEFE) model indicates that FEFE analysis can be used to predict the connection behaviour with sufficient accuracy. The experimental results and analytical sensitivity analysis demonstrate that this new connection can offer a robust and reliable moment connection for application in the low rise construction industry.