ABSTRACT
Hollow sections subjected to variable repeated axial forces and bending moments with maximum combinations of actions beyond the elastic limit but less than the static plastic limit exhibit the phenomenon of incremental collapse. The reductions in strength can be significant for structures subjected to earthquake or wave loading. Methods of estimating incremental collapse of CHS and SHS sections are given, and extended to brace-to-chord connections. In braced frames with high axial forces it is found that collapse occurs through localised axial ratchetting in members and at joints.
