Experimental study on stability of orthotropic steel box girder of self-anchored suspension cable-stayed bridge

Self-anchored suspension cable-stayed bridges generate large axial forces on the main beam, thereby affecting the stability of the steel box beam, which is essential to the stability and safety of the bridge. Herein, the stability of an orthotropic steel box girder is investigated. At first, the residual deformations of two bridge deck members with different scales was verified by welding process tests and obtained the reasonable scale of the model. The results show that the model should be designed at a scale of 1:4. Then axial compression tests were performed on a scale model of orthotropic steel box girder (length ? width ? height:10.5?3.2?1.1 m). The responses of the specimen were analyzed and discussed from different aspects considering the failure mode, load?axial deflection curves, load?out-of-plane deflection curves, and strain distribution. The instability characteristics, stress distribution relationship of the top plate, bottom plate, and webs in the transverse and longitudinal directions, actual stress state of steel deck in box girder structure and ultimate bearing capacity of the girder under axial compression were evaluated. The stability of the girder was verified considering the most unfavourable design condition. The results can provide guidance for engineering design.