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Cantilever construction bridge longitudinal prestress long and short beam division tensioning control method

A control method and prestressing technology, applied in the direction of bridges, bridge construction, erection/assembly of bridges, etc., can solve the problem of not considering the influence of steel bundle stress control, and achieve scientific and reasonable control criteria and precise prestress tension control. Effect

Inactive Publication Date: 2020-08-18
云南省公路科学技术研究院
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Problems solved by technology

[0004] At present, the "double control" principle of prestressed tension means that when the prestressed steel beam is stretched by the stress control method, the elongation value should be used for checking, and the difference between the actual elongation value and the theoretical elongation value should meet the design requirements. Requirements, when there is no regulation in the design, the difference between the actual elongation value and the theoretical elongation value should be controlled within 6%. Effect of length difference on its stress control

Method used

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  • Cantilever construction bridge longitudinal prestress long and short beam division tensioning control method
  • Cantilever construction bridge longitudinal prestress long and short beam division tensioning control method
  • Cantilever construction bridge longitudinal prestress long and short beam division tensioning control method

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Embodiment 1

[0049] A prestressed concrete continuous rigid frame bridge with a main span of 150m, the main girder adopts a single-box single-chamber section, and its longitudinal prestressed steel beams are divided into four types: "roof beams and web beams in the early stage, roof beams and floor beams in the later stage" .

[0050] According to step (1), obtain the parameter values ​​of longitudinal prestressed steel tendons: L=13.0~148.22m, k=0.0015, x=L / 2 (take the mid-span section), μ=0.20, and calculate the θ value of each steel tendon ,E p =1.95×10 5 MPa, σ con =1395MPa; the σ con Increase by 5%, and calculate the deviation Δl of the elongation value of each steel strand according to the formula (1).

[0051] According to step (2), the tensile stress deviation Δσ caused by the error of the elongation value per unit length of the steel beam is calculated according to the formula (2).

[0052] According to step (3), draw the L-Δσ diagram and perform curve fitting on the scattere...

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Abstract

The invention discloses a cantilever construction bridge longitudinal prestress long and short beam division tensioning control method which comprises the following steps: (1) acquiring bridge longitudinal prestress steel beam parameters and parameter values, changing designed tensioning control stress by + / -alpha%, and calculating steel beam elongation value deviation; (2) calculating the tensilestress deviation caused by the unit length elongation value error of the steel bundle; (3) drawing an L-delta sigma relational graph and carrying out curve fitting, wherein the correlation coefficient should be greater than or equal to 0.98; (4) solving the maximum curvature point or stationary point, namely a critical point, of the fitting curve, and taking the corresponding steel beam length L0as the critical length of long and short beam division; and (5) proposing a prestress tension control criterion based on the critical length as a threshold value. The method has the beneficial technical effects that the influence of the steel bundle length difference on stress control is considered, a prestress critical length division method and a tensioning control criterion taking the criticallength as a threshold value are provided, and technical support is provided for tensioning construction of longitudinal prestress of a cantilever construction bridge.

Description

technical field [0001] The invention relates to a tension control method for cantilever construction bridge longitudinal prestress long and short bundle division, which is mainly used to guide the tension construction of cantilever construction bridge longitudinal prestress, and belongs to the technical field of bridge construction control. Background technique [0002] For bridges with a main span of 60-200m in my country, prestressed concrete box girder bridges with strong terrain adaptability, large spanning capacity, mature design and construction technology, reasonable cost, and beautiful appearance are widely used, and the segmental cantilever pouring method is generally adopted. Construction, the length of the longitudinal prestressed steel tendons is about 10m to 60-200m (the length of the main span is quite long), whether it is the early beam, the latter beam, or the straight beam and the curved beam, there are many specifications for the length of the prestressed ste...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E01D21/10E04G21/12
CPCE01D21/10E04G21/121
Inventor 宋泽冈瞿发宪殷继华刘艳莉邓旭东陈旭丹邹磊李均进袁博李友河
Owner 云南省公路科学技术研究院
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