Uniform-section continuous beam damage identification method for curvature of damaged state support counterforce influence line
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A support reaction force, damage identification technology, applied in special data processing applications, instruments, electrical digital data processing and other directions, can solve the problem of not being able to identify the degree of structural damage
Active Publication Date: 2019-11-26
XIANGTAN UNIV
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[0005]The purpose of the present invention is to provide a damage state bearing for the existing support reaction force influence line method which cannot identify the degree of structural damage and needs information before damage Damage identification method for constant section continuous beams based on the curvature of reaction force influence line
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Embodiment 1
[0132] Embodiment one: see Figure 5 , taking a plexiglass plate model to simulate two-span continuous beams as an example, the span layout is 50+50cm, and 5cm is divided into a unit, a total of 20 units and 21 measuring points (the numbers in the upper circle in the figure are the unit numbers, The numbers in the lower row are the support numbers, and the numbers of the left and right measuring points of unit i are respectively i, i+1). The cross-sectional size is b×h=4.5cm×1.5cm, and the elastic modulus of the material is 2.7×10 3 MPa, Poisson's ratio is 0.37, density is 1200kg / m 3 .
[0133] The damage in the actual engineering structure, such as the generation of cracks, material corrosion or the reduction of elastic modulus, generally only causes a large change in the structural stiffness, but has little impact on the quality of the structure. Therefore, in the finite element calculation, it is assumed that the damage of the structural element only causes the decrease ...
Embodiment 2
[0152] Embodiment two: Simulate a three-span continuous beam with a plexiglass plate model as an example, as Figure 24 As shown, the span layout is 50+75+50cm, 5cm divides a unit, a total of 35 units, 36 measuring points (the numbers in the upper circle in the figure are unit numbers, the lower numbers are support numbers, unit i The numbers of the left and right measuring points are respectively i, i+1). Section dimensions and material parameters refer to the two-span continuous beam calculation example.
[0153] The multi-damage condition of the three-span continuous beam considers that units 1, 18, and 26 have different degrees of damage, and the damage conditions are shown in Table 2.
[0154] Table 2 Multiple damage conditions of three-span continuous beams
[0155]
[0156] The specific implementation steps are as follows:
[0157]Step 1: Apply a moving load of 120N to the damaged continuous beam respectively, and obtain the measured support reaction force influen...
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Abstract
The invention discloses a uniform-section continuous beam damage identification method for the curvature of a damaged state support counterforce influence line, and the method comprises the steps: applying a moving load to a damaged beam structure, and obtaining a damaged actual measurement support counterforce influence line; solving the curvature of the influence line, and preliminarily judgingthe damage position through the abrupt change of the curvature curve; removing the curvature value of the damaged position, carrying out piecewise linear fitting on the residual curvature curve to obtain an estimated value of the curvature of the support counterforce influence line before damage, subtracting the estimated value from the curvature of the support counterforce influence line after damage, and further judging the damaged position; conducting damage degree quantification according to the relative change of the estimated value of the curvature of the support counter-force influenceline before structural damage and the curvature of the actually-measured support counter-force influence line after damage; and if a new damage position is found, eliminating the influence of damage on the curvature fitting of the reaction influence line of the support before damage, and quantifying the damage degree again. The method can accurately position and quantify the damage of the uniform-section continuous beam, and is applied to damage evaluation of a beam structure.
Description
technical field [0001] The invention belongs to the technical field of structural health monitoring, and in particular relates to a damage identification method for continuous beams with equal cross-sections based on the curvature of a support reaction force influence line in a damaged state in the beam structure non-destructive testing technology. Background technique [0002] In recent years, there are more and more old bridges in our country, and the problems are becoming more and more obvious. Many existing bridges can no longer meet the functional requirements, and safety accidents such as bridge breakage and collapse occur from time to time. Scholars in the field of civil engineering have gradually realized the importance of health monitoring and safety assessment of bridge structures, and have studied various damage identification technologies. . Structural damage identification is an important part of the bridge structural health monitoring system. At present, there...
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