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Method for calculating change of vertical displacement in beam bridge span along with temperature

A technology of vertical displacement and calculation method, applied in the direction of calculation, computer-aided design, elasticity test, etc., can solve the problems of difficult to meet the field application of engineers, time-consuming and laborious, and troublesome application of the three-bending moment equation.

Active Publication Date: 2020-12-01
UNIV OF SCI & TECH BEIJING
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The application of the three-bending moment equation is cumbersome, and the structures with different span arrangements need to be analyzed separately, which has poor versatility
Numerical simulation is also a time-consuming and labor-intensive process. It is not easy to reveal the mechanism behind the phenomenon, and there are certain technical thresholds, so it is difficult to meet the needs of engineers for field application.
Regarding the mid-span vertical displacement of girder bridges under the action of the temperature difference between the top surface and the bottom surface, there has not been a unified calculation formula with strong versatility, simple form, and clear parameter relationships

Method used

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  • Method for calculating change of vertical displacement in beam bridge span along with temperature
  • Method for calculating change of vertical displacement in beam bridge span along with temperature
  • Method for calculating change of vertical displacement in beam bridge span along with temperature

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Embodiment 1

[0212] A girder bridge is a 6-span continuous girder structure, each span is 110m long, the main girder is made of steel, and the girder height is 4.5m. Due to direct sunlight, the temperature difference between the top and bottom surfaces of the main beam is 20°C. The vertical displacement of the bridge deck in the 1st and 3rd spans needs to be determined.

[0213] It can be seen from the above conditions that the span number n=6, which is the case of an even span continuous beam, and the number of independent node rotation angle unknowns u=3. The span of the main span and the side span are equal, l 0 =l 1 =110m, the linear expansion coefficient of the main beam is α=1.2×10 -5 °C -1 , the beam height h=4.5m, and the temperature difference between the top and bottom surfaces of the main beam is ΔT=20°C. Substituting the above parameters into equation (36) can be obtained, when k=1, Δ 1 =-0.0295m; when k=3, Δ 3 =-0.0016m. It can be seen that the vertical displacement of...

Embodiment 2

[0215] The number of spans of the girder bridge is n, the span of each span is 110m, the main girder material is steel, the girder height is 4.5m, and the temperature difference between the top surface and the bottom surface of the main girder is 20 °C. When calculating n=1,2,...,10, the mid-span vertical displacement of the main girder at the outermost side span of the girder bridge.

[0216] From the above conditions, the following parameters can be known: l 0 =l 1 =110m, α=1.2×10 -5 °C -1 , h=4.5m, ΔT=20°C, k=1. According to whether n is odd or even, substitute these parameters into Eq. (35) or Eq. (36), respectively, and let (that is, take the smallest one of the integers not less than n2), so as to obtain the mid-span vertical displacement of the main beams of the outermost side spans of girder bridges with different total spans n (in the order of increasing spans): -0.0807m, - 0.0202m, -0.0323m, -0.0288m, -0.0297m, -0.0295m, -0.0295m, -0.0295m, -0.0295m, -0.0295m. ...

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Abstract

The invention provides a method for calculating the change of vertical displacement in a beam bridge span along with temperature, and belongs to the technical field of bridge structure analysis and monitoring. The method comprises the following steps of: setting a node corner of a main beam at each support as an unknown quantity; balancing conditions according to the bending moment of the node; the method comprises the following steps of: establishing an equation, introducing a sequence, establishing a quantitative relation among unknown quantities, substituting the relational expression intothe equation, solving a corner analytical formula of each node, solving a bending moment analytical formula of each node through a superposition principle, and finally solving an analytical formula ofmidspan vertical displacement of each span girder through a virtual work principle. The method is used for a uniform-section beam bridge with equal side span length and any span number. A given analytical formula belongs to an accurate solution, calculation is convenient, universality is high, the behavior rule of the beam bridge under the temperature change is disclosed from the mechanism level,the method can be used for guiding measurement point arrangement of a bridge monitoring system, and priori knowledge is provided for establishment of a temperature deformation reference model.

Description

technical field [0001] The invention relates to the technical field of bridge structure analysis and monitoring, in particular to a method for calculating the vertical displacement of a girder bridge span with temperature changes. Background technique [0002] Simply supported beams and continuous beams are the most commonly used bridge forms in transportation networks, which are collectively referred to as girder bridges in the present invention. The structural deformation of girder bridges is the focus of structural health monitoring during bridge operation, which is usually characterized by the telescopic displacement of the girder end and the vertical displacement of the main girder at mid-span. The telescopic displacement of the main girder of the girder bridge has been well studied and can be estimated by the one-dimensional thermal expansion and contraction formula. In contrast, there are far fewer studies on the variation of the vertical displacement of the main bea...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F30/13G06F30/20G06F119/14
CPCG06F30/13G06F30/20G06F2119/14G01M5/0008G01M5/0041G06F2119/08G06F2111/10
Inventor 周毅
Owner UNIV OF SCI & TECH BEIJING
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