Measures for reducing deformation between existing and new decks in bridge widening construction under traffic load

To mitigate the deflection between existing and new decks in bridge widening construction under traffic load, the finite element method related grillage theory is used to investigate the effect of four measures and their combinations on deformation of concrete stitches or slabs. The four measures are traffic restriction, provision of temporary shear connectors between existing and new decks, provision of temporary proppings under existing bridges and segmental placement of concrete in stitches. Results show that slight traffic restriction such as close of the lane adjacent to the concrete stitches is an effective way to reduce the deformation between existing and new decks. But if traffic restriction is solely adopted, all the lanes have to be closed 6 to 8 hours after the placement of the concrete stitches. Provision of temporary proppings under existing bridges is more effective for deflection mitigation of stitches than provision of temporary shear connectors between existing and new decks, but is limited by the condition of bridge field and much expenditure. Segmental placement of concrete stitches is also an effective method but may be time consumption without careful planning. Regarding the combination of the four measures, slight traffic restriction plus provision of temporary shear connectors is a feasible and effective way to prevent cracking of concrete stitches or slabs.