Crack Control and Support Optimization of Long-Span Prestressed Concrete Box Girders During SPMT Transportation

The Hong Kong Tseung Kwan O Cross Bay Link project adopted Self-Propelled Modular Transporter (SPMT) for the first time for the floating-state loading and transportation of large-span prestressed concrete box girders, allowing the 75 m box girders to be placed on the SPMT fixture in a multi-point support manner. To prevent concrete cracking during transportation, this paper studies the stress and deformation characteristics of large-span box girders under a multi-support system through a combination of theoretical research, numerical calculation, and field testing. Based on crack control of box girders, a SPMT vehicle arrangement and segmented jacking method are proposed. The results show that the SPMT vehicle group arrangement range at both ends of the box girder should be controlled within 1/3 of the box girder span; during the jacking process of the box girder, the torsion of the box girder caused by the differential oil pressure in segmented jacking should be controlled, and synchronous jacking should be adopted as much as possible; the SPMT vehicle arrangement and jacking should control the support force to be smaller closer to the mid-span. The research results have been successfully applied in the Hong Kong Tseung Kwan O project and can provide technical reference for similar projects.