CN-122020808-A - Method for analyzing bearing capacity of cross section of large-span arch bridge under constant load dominance

CN122020808ACN 122020808 ACN122020808 ACN 122020808ACN-122020808-A

Abstract

The invention discloses a method for analyzing the section bearing capacity of a large-span arch bridge under constant load dominance, which relates to the technical field of bridge engineering, and comprises the steps of firstly analyzing the damage mode of the large-span arch bridge under a positive and negative symmetrical deformation mode, judging the eccentric limit when the section of the large-span arch bridge is damaged under the Gao Zhou force level, secondly, developing the experimental study of the damage of the bearing capacity in the large-span arch bridge deck, defining weak links and control sections of the arch structure, and finally, further analyzing and defining the influence factors of the bearing capacity in the large-span arch bridge deck based on the refined simulation model verified by the experiment. The invention solves the problem of overestimation of the nonlinear effect of bending moment by traditional equivalent Liang Zhufa, realizes the accurate analysis of the bearing capacity of the cross section of the large-span arch bridge, and provides technical support for the efficient design of the large-span arch bridge.

Inventors

LUO CHAO
ZHOU YIN
YE HONGPING
ZHOU JIANTING
ZHU JINBO
WAN LIN
ZHANG HONG
MEN PENGFEI
TANG QIZHI

Assignees

重庆交通大学
贵州省交通规划勘察设计研究院股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260213

Claims (9)

1. The method for analyzing the bearing capacity of the cross section of the large-span arch bridge under the condition of constant load is characterized by comprising the following steps of: s1, obtaining basic parameters of a large-span arch bridge, wherein the basic parameters comprise span, sagittal ratio, material mechanical property, section size, constant load and live load distribution characteristics of the arch bridge; S2, respectively deducing control differential equations of arch structures in a positive-reference deformation mode and an anti-symmetrical deformation mode based on the basic parameters and by combining plane section assumption, hooke's law and limited displacement theory; S3, based on the control differential equation, decomposing symmetrical constant load and asymmetrical movable load born by the arch bridge, analyzing stress characteristics of shaft pressure leading in a positive symmetrical deformation mode and stress characteristics of bending pressure leading in an anti-symmetrical deformation mode, and determining a section damage eccentric limit and a damage mode under the coupling action of the two deformation modes; s4, designing a reduced scale model of the large-span arch bridge based on a rigidity equivalent principle, constructing an unconstrained self-adaptive loading system and a transverse limiting device, developing a limit bearing capacity loading test of the reduced scale model, and acquiring displacement, strain and bending moment increase coefficient data in the whole loading process; S5, based on test data, establishing a double nonlinear simulation model considering geometric nonlinearity and material nonlinearity, and calibrating material constitutive parameters and boundary conditions of the simulation model through the test data; s6, simulating the section stress distribution and plastic hinge forming process under the action of positive and negative symmetrical deformation coupling by using the calibrated simulation model, and calculating the section ultimate bearing capacity; S7, analyzing the influence of the live load ratio, the structural rigidity, the reinforcement mode, the initial bending moment and the initial defect on the section bearing capacity, outputting the section bearing capacity analysis result and optimizing the arch bridge structural design.
2. The method for analyzing the bearing capacity of the cross section of the large-span arch bridge under the condition of constant load dominance according to claim 1, wherein the mechanical properties of the materials comprise compressive strength and elastic modulus of concrete, yield strength and elastic modulus of steel, the constant load comprises arch ring dead weight and arch building load, the live load comprises highway or railway moving load, and the live load distribution characteristic is quantified by the ratio of the full-span live load to the constant load.
3. The method for analyzing the bearing capacity of the cross section of the large-span arch bridge under the condition of constant load as set forth in claim 1, wherein in S2, the control differential equation corresponding to the dead-right deformation mode is: the control differential equation corresponding to the antisymmetric deformation mode is: wherein the horizontal displacement of the m point of the infinitesimal mn of any arch axis arch is The vertical displacement is Then the n-point horizontal displacement is The vertical displacement is M is the bending moment of the arch section, As an axial force at any point in the arch, Is the elastic modulus of the arch ring material, 、 For bending stiffness and cross-sectional area at any point in the arch, , 。
4. The method for analyzing the bearing capacity of the cross section of the large-span arch bridge under the constant load dominance according to claim 1, wherein in the step S3, the damage mode under the right-to-name deformation mode is five-hinge mechanism damage caused by crushing of a top plate of a arch cross section, the damage mode under the anti-symmetrical deformation mode is four-hinge mechanism damage caused by crushing of a bottom plate of a loading side arch foot cross section, and the cross section damage eccentric limit is judged by the ratio of axial compression stress to bending stress, and is small eccentric compression damage when the axial compression stress is larger than the bending stress, and is large eccentric compression damage when the axial compression stress is smaller than the bending stress.
5. The method for analyzing the bearing capacity of the cross section of the large span arch bridge under the constant load dominance according to claim 1 is characterized in that in the step S4, the design of a reduced scale model meets the principle of rigidity equivalence, the similarity ratio is determined according to the dimensional relation of length, area, volume and stress, the reduced scale ratio is 1:30-1:50, the unconstrained self-adaptive loading system adopts a lever-pulley block structure, synchronous application of constant load and half span live load is achieved, the external deformation of the molded surface is limited by a transverse limiting device, and the dominance of in-plane stress is ensured.
6. The method for analyzing the bearing capacity of the cross section of the large-span arch bridge under constant load dominance according to claim 1, wherein in the step S5, a C3D8R entity unit is adopted as a dual nonlinear simulation model to simulate concrete, a C4R plate unit is adopted as a simulation steel material, a plastic damage constitutive model is adopted as the concrete, an ideal elastoplastic constitutive model is adopted as the steel material, and the self-construction parameters are adjusted until the error is less than 5% by comparing simulation with experimental load-displacement curve and strain distribution data in the calibration process.
7. The method for analyzing the cross section bearing capacity of the large span arch bridge under the condition of constant load dominance according to claim 1, wherein in the step S6, the calculation of the cross section ultimate bearing capacity comprises the steps of obtaining the cross section maximum compressive stress based on a simulation model, taking the corresponding load as the cross section strength bearing capacity when the maximum compressive stress reaches the concrete design strength, taking the smaller value of the two as the final cross section bearing capacity when the structure forms a plastic hinge mechanism.
8. The method for analyzing the bearing capacity of the cross section of the large-span arch bridge under the condition of constant load as set forth in claim 1, wherein in the step S7, the specific mode of optimizing the structural design is that the initial bending moment is reduced by adjusting the shape of an arch axis, the rigidity of the cross section is optimized to homogenize the whole arch stress, the reinforcing steel bars are arranged on the two sides of the top plate and the bottom plate to improve the structural rigidity, and the initial defect amplitude is controlled within a range of +/-50 mm.
9. The method for analyzing the bearing capacity of the cross section of the large span arch bridge under the condition of constant load as set forth in claim 6, wherein the construction flow of the double nonlinear simulation model is specifically as follows: (1) Inputting basic information of a model in MATLAB, wherein the basic information comprises linear and vault section size and section change forms; (2) Inputting the longitudinal discrete number N of the model, and calculating the axis inclination angle of discrete points according to the arch axis of the model; (3) Setting the grid size on the cross section, calculating the two-dimensional coordinates of the cross section grid nodes at each discrete point according to the cross section size information, and generating a vault two-dimensional grid plane group; (4) Sequentially rotating and translating the dome two-dimensional grid plane group according to the discrete point coordinates and the inclination angle of the arch axis, and placing each two-dimensional grid plane at the correct position of the discrete point to obtain three-dimensional node coordinate information of the model; (5) Correspondingly connecting the nodes of the front two-dimensional grid plane and the rear two-dimensional grid plane to generate a solid unit, thereby obtaining unit information of the model; (6) Generating an initialization inp text in Abaqus, and writing the calculated model node coordinates and unit information into the inp text through MATLAB to complete the establishment of a dual nonlinear simulation model; (7) After the model inp text is built, abaqus is directly imported to generate a visual model, or MATLAB is adopted to call an Abaqus/Standard solver to carry out calculation analysis.

Description

Method for analyzing bearing capacity of cross section of large-span arch bridge under constant load dominance Technical Field The invention relates to the technical field of bridge engineering, in particular to a method for analyzing the bearing capacity of a cross section of a large-span arch bridge under constant load. Background At present, with the continuous increase of bridge spans, the problem of ultimate bearing capacity of a large-span arch bridge is more and more remarkable. The existing bridge specification adopts an 'equivalent beam column' simplified method to calculate the bearing capacity of the reinforced concrete arch rib section, but the method does not consider the true positive and negative symmetrical deformation coupling stress mode of the arch bridge, so that the bending moment increase coefficient is larger, the true bearing capacity of the large-span arch bridge is seriously underestimated, the design body quantity redundancy is caused, and the further development of the span of the arch bridge is hindered. In the existing analysis method, the arch bridge stress is mostly equivalent to a bending beam, the independent characteristics and the coupling effect of the symmetrical constant load leading positive symmetric deformation and the asymmetrical active load leading anti-symmetrical deformation are ignored, and the section damage mechanism of the large-span arch bridge under the high axial force level can not be accurately reflected. Therefore, a method for analyzing the bearing capacity of the cross section based on the real deformation mode is needed to improve the accuracy of the bearing capacity evaluation of the arch bridge and the rationality of the design. Disclosure of Invention In view of the above, the invention provides a method for analyzing the bearing capacity of a cross section of a large span arch bridge under constant load, which solves the problems in the prior art. In order to achieve the above purpose, the present invention adopts the following technical scheme: A method for analyzing the bearing capacity of a cross section of a large-span arch bridge under constant load, comprising the following steps: s1, obtaining basic parameters of a large-span arch bridge, wherein the basic parameters comprise span, sagittal ratio, material mechanical property, section size, constant load and live load distribution characteristics of the arch bridge; S2, respectively deducing control differential equations of arch structures in a positive-reference deformation mode and an anti-symmetrical deformation mode based on the basic parameters and by combining plane section assumption, hooke's law and limited displacement theory; S3, based on the control differential equation, decomposing symmetrical constant load and asymmetrical movable load born by the arch bridge, analyzing stress characteristics of shaft pressure leading in a positive symmetrical deformation mode and stress characteristics of bending pressure leading in an anti-symmetrical deformation mode, and determining a section damage eccentric limit and a damage mode under the coupling action of the two deformation modes; s4, designing a reduced scale model of the large-span arch bridge based on a rigidity equivalent principle, constructing an unconstrained self-adaptive loading system and a transverse limiting device, developing a limit bearing capacity loading test of the reduced scale model, and acquiring displacement, strain and bending moment increase coefficient data in the whole loading process; S5, based on test data, establishing a double nonlinear simulation model considering geometric nonlinearity and material nonlinearity, and calibrating material constitutive parameters and boundary conditions of the simulation model through the test data; s6, simulating the section stress distribution and plastic hinge forming process under the action of positive and negative symmetrical deformation coupling by using the calibrated simulation model, and calculating the section ultimate bearing capacity; S7, analyzing the influence of the live load ratio, the structural rigidity, the reinforcement mode, the initial bending moment and the initial defect on the section bearing capacity, outputting the section bearing capacity analysis result and optimizing the arch bridge structural design. Optionally, the mechanical properties of the material comprise compressive strength and elastic modulus of concrete, yield strength and elastic modulus of steel, the constant load comprises arch ring dead weight and arch building load, the live load comprises highway or railway moving load, and the live load distribution characteristic is quantified by the ratio of full-span live load to constant load. Optionally, in S2, the control differential equation corresponding to the positive reference deformation mode is: the control differential equation corresponding to the antisymmetric deformation mode is: wherein the horizontal displacement o