On the Optimum Design of Steel Box-girder Bridges with Regard to Stability.

The aim of the paper is to look into the effect of (i) the interaction between webs and flanges, (ii) the placing of longitudinal stiffeners and (iii) the interaction between individual flange panels on the stability problem of compression flanges. The analysis is conducted by means of folded plate theory via successive approximations. The cross-sections of the studied box girders in the first problem are depicted. The resulting critical stresses, sigma //k//r, of the compression flange are listed. An analysis of the table reveals that the restraining effect, provided by webs and influencing flange behavior, is very weak (in the studied case inferior to 3%), whatever the thickness and stiffening of the webs.