Compression strength of aged built-up column with vanished lacing bars

Recently, Japanese aged built-up members have lost their lacing bars due to corrosion. However, the remaining strength of the built-up column with vanished lacing bars has not been clarified yet. In addition, residual stress of channel-shaped steel which consists of built-up columns has not been made sufficiently clear. The authors measured the residual stress distribution of channel-shaped steel, which was removed from an aged steel truss bridge. Moreover, the authors numerically calculated the ultimate behavior of the builtup column with vanished lacing bars using the finite element method. As a result, it is found that the residual stress magnitude of the channel-shaped steel is small compared to that of the welded member, vanishment of lacing bars does not cause a significant reduction of the compression strength and column strength curve given in Japan Specifications for Highway Bridges can be used to estimate its remaining strength conservatively.