Design method for longitudinal pre-stressing tendons of variable-cross-section pre-stressed concrete continuous bridge

Abstract

The invention discloses a design method for longitudinal pre-stressing tendons of a variable-cross-section pre-stressed concrete continuous bridge. The optimization design method for the longitudinal pre-stressing tendons of the pre-stressed concrete continuous bridge is built based on the design principle of the pre-stressed degree and through combining an analytic method with a finite element method and compressively considering dead load and live load action effects. A three moment equation of the variable-cross-section pre-stressed concrete continuous box girder bridge is established to solve the internal force of the structure under the action of the self weight on the basis of the average bending moment method. A calculation formula of pre-stressed effective pre-pressure is built through a load equal effect method and a unit load method; a creep effect calculation formula is built through a force method; the temperature effect and the automobile load effect are calculated through the finite element method; and a variable-cross-section statically indeterminate structure pre-stressing tendon reinforcement calculation formula is obtained through combination of the stress ratio with the definition of the competitive pre-stressed degree.

Description

technical field [0001] The invention relates to a method for designing longitudinal prestressed beams of variable cross-section prestressed concrete continuous girder bridges. Background technique [0002] In the 1970s, with the adoption of balanced cantilever assembly method and balanced cantilever pouring construction method and the development of prestressing technology, prestressed concrete continuous beam (rigid frame) bridge has become a major bridge type in today's bridge construction. Among them, the maximum span of the prestressed concrete continuous girder bridge is within 200m, and the maximum span of the prestressed concrete continuous rigid frame bridge is within 350m. [0003] For prestressed concrete continuous girder bridges, the longitudinal prestress beam design is very important. Although the traditional design method of longitudinal prestressed beams of prestressed concrete continuous girder bridges has been continuously optimized and improved, there are...

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Problems solved by technology

The design and calculation of the longitudinal prestressed beams of prestressed concrete box girder bridges is often complicated and tedious, and the efficiency is low; sometimes the section parameters of the prestressed members are not properly selected, and even the reinforcement design of the longitudinal prestressed beams cannot be realized.

[0005] (2) The traditional prestress calculation formula is applied to the design of continuous beams with variable cross-sections, and there are limitations

For statically indeterminate structures or statically indeterminate structures with equal cross-sections, the internal force of the structure is relatively clear, the internal force effect is easy to obtain, and the calculation formula for prestressed tendons can be easily used; but for variable-section superstatically indeterminate structures, due to the geometric shape And the complexity of the geometry of the prestressed steel cable, the internal force of the main beam is very complicated, it is difficult to obtain the assumed parameters in the calculation formula of the prestressed tendon reinforcement

[0006] (3) In the design of the longitudinal prestress beam of the existing prestressed concrete continuous girder bridge, the value of the prestress degree lacks a quantitative range

In the prestressed concrete structure, the design principle of the prestressing degree method is to determine the stress state of the main girder of the prestressed concrete continuous girder bridge in the construction stage and operation stage according to the size of the prestressing degree. Size range lacks quantitative analysis

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