Lupu Bridge

There are five phases in constructing the Lupu Bridge. First is the foundations. When we talk about foundation it is the lower part that carry all the loads of the structures.The condition of the ground on either side of the Huangpu River are not appropriate for the large thrusts made by an arch bridge. Even though its arch is tied, and the use of reducing the forces transferred to the foundations, its total vertical force is still too much. And also the result of the arch being tied is that the parts of the foundations should be able to remain strong against the force. Since Lupu is located in Shanghai, and the fact that it is located near a river, it has soft soil. Therefore the most suitable option is piled foundations for that reason. Its foundations is composed of 118, 900mm diameter steel tubes ,and each pile is about 65m in length.The larger surface area of the piles and long length mean that they could be friction rather than bearing piles. This is assuming that the soil consists of clay nearer the surface moving into stiffer clay then sand lower down. The pier cap of the main span foundation is 3.5m thick and the one that connect the caps at about 51m centres are the crossbeams.. This connection between the two pier caps will help to somewhat relieve the stresses in the soil in the horizontal direction and reduce the amount of deflection incurred. By the use of 700mm diameter soil-cement stirring piles, the strength of the foundation was strengthened to help resist the horizontal force and limit the displacement due to this force. Each of these stirring piles is connected to each other to improve the integrity of the system. During construction, the foundations have a large number and stirring piles addtion due to working loads of the bridge and also due to the loads imparted on the foundations. Above each abutment the large temporary tower was built during construction. Because of that there will probably be the largest vertical force they will feel and these will impart very large vertical forces into the foundations. With the use of horizontal force impart by the inclined arches, the abutment and foundations must be strengthened in the horizontal. At an inclination similar to arches the abutment would have a high level of prestress in the concrete section and there would also be a piles coming from the abutment.