CN-118536361-B - Double-scale finite element analysis method and system for steel-concrete combined bridge

Abstract

The invention relates to a double-scale finite element analysis method and a system for a steel-concrete combined bridge, and belongs to the technical field of civil engineering. The method comprises the following steps of S1, establishing large-scale (macro-scale unit) and small-scale (fine unit) area length division in a reinforced concrete combined bridge model, defining local stress analysis key points, S2, establishing large-scale and small-scale area components and selecting component unit types, completing simplification of a double-scale model, S3, defining material structures of the large-scale and small-scale components, achieving consistency of the macro-scale units and the fine unit material scales, S4, completing assembly of space positions of the components and connection of the large-scale and small-scale areas, achieving consistency of deformation of the macro-scale and the fine model, S5, defining internal contact of the components and completing grid division, S6, applying actual loads and arranging actual boundary conditions, and performing double-scale finite element analysis. The technical scheme of the invention has the advantages of high precision, high calculation efficiency, high modeling speed and the like.

Inventors

• AN GUODONG
• ZHONG ZHIQIAO
• Ai Huaqing
• YANG FENGGANG
• ZENG KE
• LIU LIN
• Sang Yicai
• CHEN FENG
• ZHU SHIFENG
• WANG WENQIANG
• LIU ANG
• GAO WANG
• WANG HUI
• FAN LIANG
• YANG CHENGWU
• PANG XINGLIANG

Assignees

• 沧州交通发展(集团)有限责任公司
• 中交特种工程有限公司
• 重庆交通大学

Dates

Publication Date

20260505

Application Date

20240613

Claims (6)

1. 1. A double-scale finite element analysis method for a steel-concrete combined bridge is characterized by comprising the following steps of: s1, establishing large-scale and small-scale area length division in a steel-concrete combined bridge model, and determining local stress analysis key points; S2, building each large-scale and small-scale area part and selecting each part unit type to finish simplification of the double-scale model; s3, defining a material structure of each large-scale and small-scale component, and realizing consistency of macro-unit and fine-unit material dimensions; S4, assembling the space positions of all the components and connecting large and small scale areas to realize the consistency of macroscopic and fine model deformation; S5, defining internal contact of each part and completing grid division; S6, applying an actual load and arranging an actual boundary condition, and performing double-scale finite element analysis; In step S1, a large-scale area reflects macroscopic stress and deformation of a structure, and a small-scale area reflects local damage of the structure; in order to avoid the influence of boundary conditions on the results of main analysis parts, and care about the stress analysis purpose of the main local structure, selecting the length of the small-scale refined area at which the structure with the height of 1-2 times of the beam is easy to locally break; In the step S2, the model simplification comprises the model simplification of a large-scale area and the model simplification of a small-scale area, wherein the model simplification of the large-scale area comprises bridge decks, steel beams and shear members, and the method specifically comprises the following steps of: Bridge deck: 1) For the macroscopic rod system model, the concrete slab adopts the beam units, the elastic modulus of the rod system part of the concrete slab is converted according to the converted elastic modulus E s A s +E c A c ＝E 0 A 0 , the converted elastic modulus E 0 ＝(E s A s +E c A c )/A 0 is converted, wherein E s 、A s is the elastic modulus and the cross-sectional area of the reinforcing steel bar respectively, E c 、A c is the elastic modulus and the cross-sectional area of the concrete respectively, and A 0 is the converted cross-sectional area; 2) The material structure adopts ideal elastoplastic stress-strain relation for the concrete beam unit, and the stress-strain of the concrete beam unit is calculated as follows: In the method, f c is the compressive strength of the concrete, epsilon c ＝f c /E 0 is the strain corresponding to the compressive strength, E 0 is the equivalent strain of the concrete with the converted elastic modulus epsilon i , and sigma i is the equivalent stress of the concrete; And (3) steel beam: 1) The steel beam is simplified, wherein the steel beam is simplified into beam units with the cross section of the steel beam in a macroscopic rod system model, and each section is respectively combined in a double-scale model, and the beam units are adopted for the macroscopic rod system model; 2) The material structure has the advantages that the structure model can well reflect the stress-strain relation of steel in the stress process, and a two-fold line model is adopted for the steel beam, and the stress-strain relation has the following calculation formula: Wherein E s is a steel beam elastic die, sigma s 、ε s is steel beam stress and strain, f y 、ε y is steel beam yield strength and yield strain, and f u 、ε u is steel ultimate strength and ultimate strain respectively; Shear member: 1) The shear member is simplified by adopting a spring unit to simulate the mechanical behavior of the shear member, using a spring unit with 2 nodes to establish connection between the bottom of the concrete slab and the upper flange of the steel beam, and describing the mechanical behavior of the shear member in the translational and rotational directions by defining the combined connection attribute; 2) The shear member mechanism mainly comprises a friction stage, a sliding stage, an elastic stage and an elastoplastic stage in the stress process of the shear member, and the mechanical behavior of an actual shear member is simulated by defining the load-sliding curve constitutive relation of a connecting unit.
2. 2. The method for analyzing the double-scale finite element of the reinforced concrete composite bridge, as set forth in claim 1, wherein the model simplification of the small-scale region comprises the following steps: the bridge deck plate is arranged at the same position in the refined model, and adopts solid units, and the steel bars adopt truss units; ① Single-shaft compression structure for concrete σ=(1-d c )E c ε Wherein, the ② Single-shaft tension structure for concrete σ=(1-d t )E c ε Wherein, the The general steel bar stress-strain calculation formula is as follows: Wherein sigma j is the equivalent stress of the common reinforcing steel bar, E s is the elastic modulus of the common reinforcing steel bar, epsilon j is the equivalent strain of the common reinforcing steel bar, and f y is the yield strength of the common reinforcing steel bar; The steel beam is arranged at the same position in the refined model and adopts a thin-wall shell unit, and the material structure comprises the steel beam adopting a two-fold line model, wherein the calculation formula of the stress-strain of the steel beam is as follows: Wherein E s is a steel beam elastic die, sigma s 、ε s is steel beam stress and strain, f y 、ε y is steel beam yield strength and yield strain, and f u 、ε u is steel ultimate strength and ultimate strain.
3. 3. The method for analyzing the double-scale finite element of the reinforced concrete composite bridge, which is disclosed in claim 2, is characterized in that in the step S4, because the spatial degrees of freedom between different units are different, when the unit connection coupling is performed, in order to achieve the balance and deformation coordination of forces among the three units, rigid connection is adopted for coupling, wherein beam unit nodes are master nodes, points on the entity and the shell units are slave nodes, and the master nodes are connected with the beam unit nodes in the refined model through rigid arms, so that the deformation coordination of the master node and the slave node is ensured.
4. 4. The method for analyzing the double-scale finite element of the reinforced concrete composite bridge according to claim 3, wherein in the step S5, after the assembly of each component, the contact surface relation of each component needs to be defined, mainly comprising the contact relation between the concrete slab and the steel girder and the contact relation between the reinforcing steel bar net and the concrete slab in the refined model, and in addition, as for the macroscopic model part, the contact relation is not required to be set because the steel girder and the bridge deck are connected through a spring unit, the method specifically comprises the following steps: 1) The interface contact between the concrete slab and the steel beam, which is to set normal hard contact and tangential friction-free contact relation to the steel-concrete interface, considering that the bonding force between the steel beam and the concrete slab is negligible, 2) the interface contact between the reinforced mesh and the concrete slab, which is to cooperatively stress the reinforced mesh in the concrete, to ensure that the concrete is not cracked too early, the bonding sliding action between the reinforced mesh and the concrete slab is ignored, and the contact relation between the reinforced mesh and the concrete slab is simulated by adopting the built-in reinforced mesh.
5. 5. The method for analyzing the double-scale finite element of the reinforced concrete composite bridge, which is disclosed in claim 4, is characterized in that in the step S5, after the interfaces are contacted with each other, the grid division is needed for the components, and the grid size division is needed according to the stress difference of the components aiming at different types of models, so that the force transmission simulation at the special position is more accurate.
6. 6. A double-scale finite element analysis system for a steel-concrete composite bridge, which is characterized in that the system adopts the method as set forth in any one of claims 1 to 5.

Description

Double-scale finite element analysis method and system for steel-concrete combined bridge Technical Field The invention belongs to the technical field of civil engineering, and relates to a double-scale finite element analysis method and system for a reinforced concrete combined bridge. Background Currently, according to different dimensions of research objects, the finite element modeling analysis method in the bridge engineering field mainly comprises the following three steps of ① building a large-scale full-bridge macroscopic model with a rod system beam unit, ② building a small-scale local construction microscopic model with a solid unit and a shell unit, and ③ building a small-scale full-bridge refined model with the solid unit and the shell unit. 1) The full-bridge macroscopic model adopting the bar system beam unit is a highly simplified integral structure model, can reflect the stress performance of the whole bridge under the action of constant load and live load, but cannot reflect the stress on structural details, and 2) the local refined model adopting the shell unit and the entity unit is adopted, and the local component is used as a separator, so that the whole full-bridge model with macroscopic large scale is firstly established for carrying out integral analysis, the internal force and displacement are extracted, and then the displacement and load boundary conditions are applied on the separator for balancing, so that the stress of the separator is analyzed. The modeling method has the advantages of high modeling speed and high calculation efficiency, meets the requirement of stress analysis of small-scale local microcosmic components, but has complex boundary conditions of an extracted isolator or difficult determination of boundary conditions of a model, 3) adopts a full-bridge refined finite element model of a solid and a shell unit, and has no local structural boundary simulation by applying real boundary conditions and loads on the finite element model, so that the analysis result is accurate and reliable, but the modeling method has obvious defects, along with the increase of structural space dimensions, the modeling speed is low, the calculation efficiency is low, and the calculation data is huge. Therefore, for the actual large and complex bridge three-dimensional structure, the local structural stress is concerned, the whole bridge macroscopic whole stress analysis is required, and the modeling method can not meet the requirements of actual engineering. In recent years, a multi-scale simulation method of a structure has been widely used in engineering structures, which first appears in material disciplines, and which is then used in the structure as engineers need to pursue a balance of computational accuracy and time cost in computational analysis. For the multi-scale structure, under the action of load, local components are usually damaged due to stress concentration, and the damage of the local components further leads to the instability of the whole structure, wherein the damage of the local components is a microcosmic small scale, and the instability of the whole structure is a macroscopic large scale, and the damage belongs to different scale orders. The core idea of the multi-scale simulation is to combine a small-scale fine model with a large-scale rod system model, replace the original boundary condition of the small-scale fine model by a reasonable interface connection mode, and then add the real boundary condition into the large-scale model, so that the multi-scale model has the advantages of the large-scale model and the small-scale model at the same time, and the defects of the multi-scale model are overcome, and the multi-scale simulation has the characteristics of low calculation cost and high result precision. At present, the multi-scale finite element simulation method is mainly focused on application research on concrete bridges or steel bridges, but the research on steel-concrete combined bridges is less. The steel-concrete combined bridge relates to two materials of steel and concrete, the steel and the concrete are connected by virtue of a shear connector, and the interface between the steel and the concrete is not completely and continuously slipped. Disclosure of Invention In view of the above, the present invention aims to provide a method and a system for dual-scale finite element analysis of a reinforced concrete bridge, which relate to the problems of nonlinearity of materials of reinforced concrete bridge slabs and steel beams and outstanding slippage of reinforced concrete interfaces, namely, a macroscopic beam unit with high calculation efficiency and a fine entity unit with high precision are contained in the same calculation model, and different units are connected through coupling, so that the time and the precision of the calculation of the structure are balanced. In order to achieve the above purpose, the present invention provides the following te