Long-Term Effect Of Prestress On Self-Anchored Suspension Bridge

Because cables of the self-anchored suspension bridge are anchored on the stiffening girder, stiffening girder would generate elastic deformation in the construction process of cables installation, hangers pulling and deck pavements, that causes the new loss, which to be called the supplementary loss of prestressing force. Besides, the stress relaxation of prestressed reinforcement, shrinkage and creep of concrete would cause the loss of prestressing force along the time, which to be called long-term loss of prestressing force. The supplementary and long-time loss of prestressing force, the shrinkage and creep of concrete must induce the internal force redistribution of structure. The co-action of supplementary and long-time loss of prestressing force, the shrinkage and creep of concrete must be taken into account in the design of structure.The thesis briefly presents the basic principle of prestressed concrete, carries out the analysis and compares domestic and calculation methods of prestressing force losing , useing the time-interval method and sum of subitem method to calculate the loss of prestressing force, deduces the methods to calculate the lose of each item of prestressing force, and establishes the corresponding programme; using the equivalent loads methods to deal with the structure, deduces the methods to calculate equivalent loads of each form of reinforced bar, and establishes the corresponding programme.The thesis takes two patterns of self-anchored suspension bridge as examples to carry on the structure analysis of prestressing, shrinkage and creep effects to the structure with BNLAS calculation system. The result indicates that the prestressing force, shrinkage and creep effects have a long term influences on the self-anchored suspension bridge; and it became greater along the time, but the change speed became more slowly. The reasonable end time of shrinkage and creep should be determined according to the idiographic types of structure; long-time loss of prestressing force reduced the adverse influences of inner force and line shapes on the structure by the shrinkage and creep of concrete.