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Creep Stress on the Contact Surface of Twice-prestressed Composite Beam in High-speed Railway Bridge

Author: HuYunYao
Tutor: LuoJianHui
School: Hunan University
Course: Structural Engineering
Keywords: High - speed railway bridges Secondary prestressed composite beams Creep Combination of surface stress Trigonometric series Minimum complementary energy principle
CLC: U441.5
Type: Master's thesis
Year: 2009
Downloads: 62
Quote: 0
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Abstract


Secondary prestressed composite structure is a new structure type used in the field of bridge structures in prestressed concrete technology. This prestressed technology in the crack resistance of the bridge structure and deformation control has an obvious advantage. Special high-speed railway bridge has strict restrictions creep camber secondary prestressed composite beam structure, both to meet the force requirements can reduce the creep arch, is a worthy application of new prestressed structures. Double prestressed composite structure due to construction technology instars part of the cross-section dead load stress is different, different dead load stress of the age difference, will inevitably lead to the longitudinal fiber creep deformation uncoordinated, under common deformation constraints, caused by the redistribution of stress on the cross-section, usually called creep due to stress redistribution. Using linear creep theory and theory of aging, compatibility conditions according to the change of curvature, the equilibrium conditions of stress increment and stress increment creep strain deformation compatibility conditions, calculated considering the the secondary beam cross-section two dead load effects, which calculate the the strain increment curvature incremental, calculated by curve fitting the secondary beam creep on arch. Trial compared to verify this creep calculated theoretical methods used to calculate the secondary prestressed composite beams is feasible verified Twice Prestressed composite beams used in high-speed railway bridge control the creep deformation feasibility and superiority. Two parts concrete pouring back and forth in the secondary prestressed composite beams should be able to form an overall cross section and work together, combined with reliable bonding surface is to ensure that work together key. Thus figure out the combination of the stress state of the surface is very meaningful. External loads and creep are caused by a combination of surface stress. Creep deformation secondary prestressed composite beams longitudinal fibers by mutual constraints will generate the distribution of stress in the joint surface, with a modulus of elasticity with age adjustment instead of the elastic modulus of concrete creep effect equivalent to load role in the structure of the elastic trigonometric series describes the combination of surface stress minimum complementary energy principle to consider a combination of surface deformation coordination, solving creep due to the joint surface (horizontal) stress distribution. The combination of surface creep stress distribution through examples drawn: the combination of surface creep stress are mainly distributed in the precast beam beam end. And discuss the major parameter changes of surface creep stress: with the role of a prestressed precast beam concrete compressive stress increases; increase with a prestressed precast beams loaded reduce age large; decreasing with the number of days between a the prestressed tension to two concrete pouring; decreasing; With the the environmental average annual humidity with concrete grade decreased with the increase.

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CLC: > Transportation > Road transport > Bridges and Culverts > Structural principles, structural mechanics > Stress analysis, thermal stress
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