WEB BUCKLING CAPACITY OF STEEL BRIDGE BOX GIRDERS DURING INCREMENTAL LAUNCHING

Abstract

An important design component of steel girders erected via launching is the need to be designed for effects of combined bending moment and a traveling patch load applied by the roller bearing. Although the Canadian Highway Bridge Design Code (CSA S6, 2019) addresses web yielding and web crippling at the ultimate limit state, little guidance is provided to determine the buckling capacity of the web panel while the stress level is low. Field work and a numerical study were conducted to develop an understanding of the behaviour of box girder webs subjected to patch load combined with flexure in the elastic range. The numerical study investigated the effects of several influential geometric parameters on web buckling of box girders. The comparison of numerical results with design equations from CSA S6 (2019) shows that web panel buckling can occur at lower load levels than those causing web yielding or crippling.