Existing non-conforming steel truss frames used in factories constructed during Japan’s high economic growth period are at risk of severe damage during major earthquakes. To promote the implementation of retrofitting methods that enable seismic strengthening without interrupting operations, it is essential to clarify the structural performance of these frames under large-deformation cyclic loading. In this study, the mechanical behavior of steel truss beams and individual chord members up to fracture was investigated through experimental testing. Based on the results, a hysteretic model incorporating fracture was proposed to represent the seismic performance of existing non-conforming steel truss beams.
