Internal Redundancy of Mechanically Fastened Built- Up Steel Axially Loaded Two-Channel Members

Previous research on large-scale fracture tests on mechanically fastened built-up steel members subjected to flexural or axial loads demonstrated resistance to complete member fracture due to cross-boundary fracture resistance (CBFR). This paper builds on and expands that work through additional experimental and analytical research into behavior of two-channel mechanically-fastened built-up axial steel members following fracture of a single component. Finite-element-based parametric studies were conducted to characterize the static load redistribution behavior of axial members comprised of two channels, following a fracture event. FEMs were calibrated using experimental data obtained from full-scale testing. Simplified solutions were developed to estimate the after-fracture load capacity and the fatigue stress range in a remaining channel. The solutions are used to evaluate the internal redundancy of mechanically fastened built-up two-channel members. If this member type is found to be internally redundant during an evaluation, the developed solutions can then be used to reliably predict fatigue life of the member in the faulted state and establish the special inspection interval according to the relevant provisions of AASHTO.