Corrugated steel web box girder lining concrete cracking risk analysis method and system

Abstract

The invention provides a corrugated steel web box girder lining concrete cracking risk analysis method and system. Displacement boundary conditions and temperature boundary conditions are set, a corrugated steel web lining concrete model is established, numerical calculation is conducted on the corrugated steel web lining concrete model, and numerical calculation results are analyzed. Based on a numerical calculation result, taking a shrinkage effect, creep, a concrete mold entering temperature and a concrete surface heat preservation measure as consideration factors, and analyzing the influence of each consideration factor on the cracking risk of the corrugated steel web lining concrete; and according to the influence of all the consideration factors, the cracking risk of the target corrugated steel web lining concrete in the target environment is determined and adjusted. According to the method disclosed by the invention, the crack resistance of the lining concrete is analyzed by considering the hydration heat release efficiency, the elastic modulus change and the shrinkage creep behavior of the concrete, and the crack risk is favorably determined.

Description

Technical Field

[0001] The present invention belongs to the technical field of bridge engineering, and particularly relates to a method and system for analyzing the cracking risk of the concrete lining inside a corrugated steel web box girder. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention, and do not necessarily constitute prior art.

[0003] The corrugated steel web is a steel-concrete composite structure, which has the advantages of light structure, good seismic performance, reasonable stress, simple construction and economical project cost. When the span of the corrugated steel web box girder bridge is relatively large, the height of the box girder root section is correspondingly high. In the design, concrete is generally poured inside the corrugated steel web near the pier top, that is, the concrete lining. The cracking mechanism of the concrete lining is relatively complex. Among them, the cracking under the strong restraint state of the corrugated steel web at the early age is the main reason, and the early-age cracking of concrete is caused by the comprehensive superposition of various factors such as the heat of hydration of cement in concrete, the early-age shrinkage and creep of concrete, and the gradual development of elastic modulus.

[0004] At present, there are already engineering cases of cracking in corrugated steel web box girders. At present, there are few research results on the anti-cracking mechanism and engineering suggestions during the construction process of corrugated steel web box girders at home and abroad. The analysis of the reasons for the early-age cracking of the concrete lining inside the corrugated steel web box girder is relatively single, and there is a lack of accurate and effective analysis methods for the cracking risk. Therefore, there is an urgent need for a method that comprehensively considers the heat release efficiency of hydration heat, the change of elastic modulus, and the shrinkage and creep behavior to reveal the early-age cracking risk of the concrete lining. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a method and system for analyzing the cracking risk of the concrete lining inside a corrugated steel web box girder. On the basis of considering the heat release efficiency of concrete hydration heat, the change of elastic modulus, and the shrinkage and creep behavior, the present invention conducts numerical simulations, and analyzes the crack resistance performance of the concrete lining from four aspects of shrinkage effect, creep, concrete pouring temperature and convection coefficient based on an actual continuous corrugated steel web girder bridge, which helps to determine the cracking risk and the results are relatively accurate.

[0006] According to some embodiments, the present invention adopts the following technical solutions:

[0007] A method for analyzing the cracking risk of the concrete lining inside a corrugated steel web box girder, comprising the following steps:

[0008] Set displacement boundary conditions and temperature boundary conditions, establish a corrugated steel web concrete lining model, perform numerical calculations on the corrugated steel web concrete lining model, and analyze the numerical calculation results;

[0009] Based on the numerical calculation results, considering the shrinkage effect, creep, concrete placement temperature, and concrete surface thermal insulation measures, analyze the influence of each consideration factor on the cracking risk of the concrete lining inside the corrugated steel webs;

[0010] According to the influence of each consideration factor, during the design stage of the concrete lining inside the corrugated steel web box girder, calculate the influence of shrinkage and creep effects on the crack resistance of the lining concrete, and then adjust the relevant design parameters. During the construction stage of the concrete lining inside the corrugated steel web box girder, adjust the concrete placement temperature and conduct concrete surface thermal insulation treatment to reduce the early-age cracking risk of the concrete lining inside the corrugated steel web box girder.

[0011] As an alternative implementation method, when setting the displacement boundary, consider the restraint effect of the diaphragm and the restraint effect of the already poured part on the unpoured part.

[0012] As a further step, the concrete lining model with corrugated steel webs includes multiple segments, where N - 1 segments simulate the already poured segments, considering the concrete to be cured and not considering the concrete hydration heat; the Nth segment is the currently poured concrete part, considering that there is concrete hydration heat in this part;

[0013] Restrain the displacements in three directions at the concrete interface between the already poured segments N - 1 and N - 2. Consider the influence of the diaphragm at the front end of the concrete in the Nth segment and restrain the lateral displacement. At the same time, restrain the displacements in three directions at the top and bottom.

[0014] As an alternative implementation method, when setting the temperature boundary, use the heat convection model to simulate the external heat loss and set the temperature boundary according to the simulation results.

[0015] As an alternative implementation method, when analyzing the crack resistance of the concrete lining inside the corrugated steel webs based on the numerical simulation results, compare the vertical stress magnitudes of the concrete lining inside the corrugated steel webs under two cases: considering and not considering the shrinkage effect, and determine the influence of the shrinkage effect on the crack resistance of the concrete lining inside the corrugated steel webs.

[0016] As an alternative implementation method, when analyzing the crack resistance of the concrete lining inside the corrugated steel webs based on the numerical simulation results, compare the vertical stress magnitudes of the concrete lining inside the corrugated steel webs under two cases: concrete shrinkage plus creep and concrete shrinkage, so as to determine the influence of creep on the crack resistance of the concrete lining inside the corrugated steel webs.

[0017] As an alternative implementation method, when analyzing the crack resistance of the concrete lining inside the corrugated steel webs based on the numerical simulation results, compare the vertical stress magnitudes of the concrete lining inside the corrugated steel webs at different concrete placement temperatures, so as to determine the influence of the concrete placement temperature on the crack resistance of the concrete lining inside the corrugated steel webs.

[0018] As an alternative embodiment, when analyzing the crack resistance performance of the inner lining concrete based on the numerical simulation results, compare the vertical stress magnitudes of the inner lining concrete under different convection coefficients on the surface of the inner lining concrete, so as to determine the influence of the surface convection coefficient on the crack resistance performance of the inner lining concrete, and further determine the influence of the concrete surface heat preservation measures on the crack resistance performance of the inner lining concrete.

[0019] As an alternative embodiment, the process of determining the cracking risk of the target corrugated steel web inner lining concrete in the target environment includes: based on the influence of each considered factor and combined with the numerical simulation results, determine whether there is a cracking risk for the target corrugated steel web inner lining concrete under the service environment of the target area, at the set concrete placement temperature, and with the proposed concrete surface heat preservation measures.

[0020] A system for analyzing the cracking risk of the inner lining concrete of a corrugated steel web box girder includes:

[0021] A model simulation module, configured to set displacement boundary conditions and temperature boundary conditions, establish a corrugated steel web inner lining concrete model, perform numerical calculations on the corrugated steel web inner lining concrete model, and analyze the numerical calculation results;

[0022] An influence analysis module, configured to analyze the influence of each considered factor on the cracking risk of the corrugated steel web inner lining concrete based on the numerical calculation results, with shrinkage effect, creep, concrete placement temperature, and concrete surface heat preservation measures as the considered factors;

[0023] A parameter adjustment module, configured to calculate the influence of shrinkage and creep effects on the crack resistance performance of the inner lining concrete during the design stage of the corrugated steel web box girder inner lining concrete based on the influence of each considered factor, and then adjust the relevant design parameters. During the construction stage of the corrugated steel web box girder inner lining concrete, adjust the concrete placement temperature and perform concrete surface heat preservation treatment to reduce the early-age cracking risk of the corrugated steel web box girder inner lining concrete.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] The present invention comprehensively considers the heat release efficiency of hydration heat, the change of elastic modulus, and the shrinkage and creep behavior to reveal the early-age cracking risk of the inner lining concrete. Furthermore, during the design stage of the actual corrugated steel web box girder inner lining concrete, calculate the influence of shrinkage and creep effects on the crack resistance performance of the inner lining concrete, and then adjust the relevant design parameters. During the construction stage of the actual corrugated steel web box girder inner lining concrete, adjust the concrete placement temperature and perform concrete surface heat preservation treatment to reduce the early-age cracking risk of the corrugated steel web box girder inner lining concrete, which helps to improve the safety of bridge engineering.

[0026] Based on the consideration of the heat release efficiency of concrete hydration heat, the change of elastic modulus, and the shrinkage and creep behavior, numerical simulations were carried out in this invention. Relying on the actual corrugated steel web continuous girder bridge, the crack resistance performance of the lining concrete was analyzed from four aspects: shrinkage effect, creep, concrete placing temperature, and convection coefficient, which helps to determine the cracking risk and the results are relatively accurate.

[0027] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given, and in conjunction with the attached drawings, the detailed description is as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0029] Figure 1 Construction drawing of the corrugated steel web lining concrete model established for an embodiment;

[0030] Figure 2 Boundary condition definition drawing of the corrugated steel web lining concrete model for an embodiment;

[0031] Figure 3 Numerical model selection and analysis position drawing of the corrugated steel web lining concrete model for an embodiment;

[0032] Figure 4 Stress analysis position drawing selected in the corrugated steel web lining concrete model for an embodiment;

[0033] Figure 5 Influence analysis drawing of shrinkage on stress for an embodiment;

[0034] Figure 6 Influence analysis drawing of creep on stress for an embodiment;

[0035] Figure 7 Influence analysis drawing of concrete placing temperature on stress for an embodiment;

[0036] Figure 8 Influence analysis drawing of convection coefficient on stress for an embodiment;

[0037] Figure 9 Lining concrete cracking position drawing in the corrugated steel web lining concrete model for an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The present invention will be further described below in conjunction with the drawings and embodiments.

[0039] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0040] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] In the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0042] Embodiment 1

[0043] A method for analyzing the cracking risk of the concrete lining in a corrugated steel web box girder, comprising the following steps:

[0044] Step 1: Set displacement boundary conditions and temperature boundary conditions, establish a corrugated steel web concrete lining model, perform numerical calculations on the corrugated steel web concrete lining model, and analyze the numerical calculation results;

[0045] Step 2: Based on the numerical calculation results, take the shrinkage effect, creep, concrete placement temperature, and concrete surface heat preservation measures as consideration factors, and analyze the influence of each consideration factor on the cracking risk of the corrugated steel web concrete lining;

[0046] Step 3: Determine the cracking risk of the target corrugated steel web concrete lining in the target environment according to the influence of each consideration factor.

[0047] When establishing the corrugated steel web concrete lining model in Step 1, the restraint effect of the diaphragm and the restraint effect of the already cast part on the uncast part are considered when setting the displacement boundary, as Figure 2 shown.

[0048] In Step 1, when establishing the corrugated steel web concrete-filled model, the heat convection boundary is used to simulate the heat exchange between the concrete-filled part and the atmospheric environment when setting the temperature boundary. The specific implementation method is that the corrugated steel web and the concrete share nodes, and the heat generated by the hydration heat of the lining directly transfers heat to the steel web. The convection coefficient is set on the surface where the steel web contacts the atmosphere and the surface where the concrete-filled lining contacts the atmosphere at the same time to simulate the heat dissipation in the form of heat convection. The specific parameters are thermal conductivity k = 1.87 W / (m·K), coefficient of thermal expansion α = 8.53E-06 K-1, specific heat capacity cp = 1045 J / (kg·K), and convection coefficient h = 7.9 W / (m2·K). At the same time, an indoor model experiment is carried out to verify the effectiveness of the model.

[0049] As Figure 1 shown, in Step 1 of the present invention, a corrugated steel web concrete-filled model is established, and the actual size parameters are as follows: the length of the concrete-filled lining is 3.2 m, the height is 7 m, and the thickness is 0.3 m. The corrugated steel web uses a 1600-type corrugated steel plate, and the material is Q420qD steel. The horizontal section length of the corrugation of the steel web is 430 mm, the inclined section length is 430 mm, the horizontal length in the inclined section is 370 mm, the wave height is 220 mm, and the thickness is 28 mm. Dense studs are welded inside the corrugated steel web, so the steel web and the concrete are consolidated by TIE. Figure 3 In the construction drawing, the N-1 section simulates the already poured section, and it is considered that the concrete has solidified, and the concrete hydration heat is not considered; the N section is the current concrete pouring part, and it is considered that there is concrete hydration heat in this part.

[0050] As Figure 2 shown, in the boundary condition definition drawing, both the N-1 section and the N-2 section are already poured sections, so the displacements in three directions are constrained at the concrete interface between the N-1 section and the N-2 section. In the N section, considering the influence of the diaphragm at the front end of the concrete, the lateral displacement is constrained, and at the same time, the displacements in three directions are constrained at the top and bottom.

[0051] As Figure 3 shown, in Step 2, calculations are carried out on the corrugated steel web concrete-filled model, and the results collected by the on-site sensors are compared with the results calculated by the numerical model. Point P is selected as the point for numerical analysis, and whether the elastic strain at point P is close to the data of the measured strain sensor is compared to judge whether the established corrugated steel web concrete-filled model can accurately reflect the actual structural strain.

[0052] As Figure 4 shown, in Step 2 of the present invention, calculations are carried out on the corrugated steel web concrete-filled model, and the results calculated by the numerical model are analyzed. The stress of the corrugated steel web is analyzed to obtain the position and numerical value where the maximum vertical tensile stress of the corrugated steel web appears; the distribution of the vertical stress field of the concrete-filled lining at different times is analyzed to judge the position where the concrete-filled lining starts to crack for the first time.Figure 4 In this case, four points A, B, C, and D are selected on the model as the stress analysis positions of the lining concrete. By analyzing the vertical stress time history of the four points, the tensile and compressive stress states of the concrete at different times, as well as the position and value of the maximum vertical tensile stress, are obtained.

[0053] As Figure 5 shown, in step 4 of the present invention, based on numerical simulation, the effects of shrinkage effect, creep, concrete placement temperature, and concrete surface heat preservation measures on the maximum vertical stress of the lining concrete are analyzed. Furthermore, the effects of different influencing factors on the crack resistance of the concrete with corrugated steel webs as lining are analyzed. The main analysis contents consist of the following four parts:

[0054] (1) Concrete shrinkage causes internal constraints, thereby generating additional stresses in the concrete. Analyze the influence of the shrinkage effect on the vertical stress of the lining concrete, and compare the vertical stress of the lining concrete in two cases: considering and not considering the shrinkage effect. It is found that the shrinkage effect has a certain degree of influence on the cracking of the lining concrete. For the research object of the present invention, compared with the model considering the shrinkage effect, in the model not considering the shrinkage effect Figure 4 the vertical tensile stress at point D decreases by about 8%, as Figure 5 shown. Thus, it is pointed out that by adequately sprinkling water for curing the model, the tensile stress of the concrete can be reduced to a certain extent, and the cracking risk of the lining concrete can be reduced;

[0055] (2) After the creep of the concrete occurs, the stress level of the concrete will be reduced. Analyze the influence of creep on the vertical stress of the lining concrete, and compare the vertical stress of the lining concrete in two cases: concrete shrinkage + creep and concrete shrinkage. It is found that the influence of creep needs to be considered emphatically to accurately simulate the stress level of the early-age lining concrete. For the research object of the present invention, if the material characteristics of creep are not considered, the stress level of the concrete will be overestimated significantly, Figure 4 and the increase amplitude of the vertical tensile stress at point D in Figure 6 reaches 46.2%, as

[0056] (3) The concrete placement temperature affects the form of the vertical stress. Analyze the influence of the placement temperature on the vertical stress of the lining concrete, and compare the vertical stress of the lining concrete in four cases: 10°C, 15°C, 20°C, and 25°C. It is found that reducing the placement temperature of the lining concrete can effectively reduce the cracking risk of the lining concrete. For the research object of the present invention, for every 1°C change in the placement temperature, Figure 4 the vertical tensile stress at point D in Figure 7 will increase by 0.345 Mpa, as

[0057] (4) The convective coefficient affects the heat transfer efficiency between the concrete and the atmosphere. After the thermal insulation engineering measures are adopted on the concrete surface, the convective coefficient will change. Analyze the influence of the convective coefficient on the vertical stress of the lining concrete, and compare the vertical stresses of the lining concrete under four conditions of 8.4, 14.2, 20, and 28.4 kJ / (m 2 h℃). It is found that the smaller the convective coefficient on the surface of the lining concrete, the lower the tensile stress of the concrete, and the lower the cracking risk of the lining concrete. For the research object of the present invention, when the convective coefficient changes from 8400 J / (m 2 h℃) to 28400 J / (m 2 h℃), Figure 4 the vertical tensile stress at point D in [figure] increases from 1.6 MPa to 3.1 MPa, approximately doubling, as Figure 8 shown, thus indicating that in actual engineering, a foam plastic board (1 cm thick, convective coefficient of 9600 kJ / (m 2 h℃)) can be used to implement the thermal insulation of actual engineering.

[0058] In step 3, according to the influence of each considered factor and combined with the numerical simulation results, determine whether there is a cracking risk for the target corrugated steel web lining concrete under the service environment of the target area, at the set concrete placement temperature, and under the proposed concrete surface thermal insulation measures.

[0059] By determining the cracking risk of the target corrugated steel web lining concrete in the target environment, further calculate the influence of shrinkage and creep effects on the crack resistance of the lining concrete during the design stage of the corrugated steel web box girder lining concrete, so as to adjust the relevant design parameters. During the construction stage of the corrugated steel web box girder lining concrete, adjust the concrete placement temperature and conduct concrete surface thermal insulation treatment to reduce the early-age cracking risk of the corrugated steel web box girder lining concrete, which helps to improve the safety of bridge engineering.

[0060] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made by those skilled in the art without creative efforts within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for analyzing the risk of cracking of lined concrete of a corrugated steel web box girder, characterized in that: The following steps are involved: Set displacement boundary conditions and temperature boundary conditions, establish a corrugated steel web lining concrete model, perform numerical calculations on the corrugated steel web lining concrete model, and analyze the numerical calculation results; Based on the numerical calculation results, the shrinkage effect, creep, concrete mold temperature and concrete surface insulation measures are taken into consideration to analyze the impact of various factors on the cracking risk of corrugated steel web lining concrete. According to the influence of various factors, during the design stage of the inner lining concrete of the corrugated steel web box girder, the influence of shrinkage and creep effects on the crack resistance of the inner lining concrete is calculated, and then the relevant design parameters are adjusted. During the construction stage of the inner lining concrete of the corrugated steel web box girder, the concrete mold entry temperature is adjusted and the concrete surface insulation treatment is carried out.

2. A method for analyzing cracking risk of lined concrete of a corrugated steel web box girder as claimed in claim 1, characterized in that: When setting the displacement boundary, consider the restraint effect of the diaphragm and the restraint effect of the cast part on the uncast part.

3. A method for analyzing cracking risk of lined concrete of a corrugated steel web box girder as claimed in claim 2, characterized in that: The corrugated steel web lining concrete model includes multiple segments, wherein segment N-1 simulates the cast segment, and the concrete is considered to be solidified, and the concrete hydration heat is not considered; segment N is the current concrete casting part, and it is considered that there is concrete hydration heat in this part; The displacement in three directions is constrained at the concrete interface between the cast segments N-1 and N-2. The influence of the diaphragm is considered at the front end of the concrete in segment N to constrain the lateral displacement. At the same time, the displacement in three directions is constrained at the top and bottom.

4. A method for analyzing cracking risk of lined concrete of a corrugated steel web box girder as claimed in claim 1, characterized in that: When setting the temperature boundary, the thermal convection model is used to simulate the external heat loss, and the temperature boundary is set according to the simulation results.

5. A method for analyzing the risk of cracking of the inner lining concrete of a corrugated steel web box girder as claimed in claim 1, characterized in that When analyzing the anti-cracking performance of the lining concrete based on the numerical simulation results, the vertical stress of the lining concrete is compared with and without considering the shrinkage effect to determine the influence of the shrinkage effect on the anti-cracking performance of the lining concrete.

6. A method for analyzing the risk of cracking of the inner lining concrete of a corrugated steel web box girder as claimed in claim 1, characterized in that When analyzing the anti-cracking performance of the lining concrete based on the numerical simulation results, the vertical stress of the lining concrete under the two conditions of concrete shrinkage plus creep and concrete shrinkage is compared to determine the influence of creep on the anti-cracking performance of the lining concrete.

7. A method for analyzing the risk of cracking of the inner lining concrete of a corrugated steel web box girder as claimed in claim 1, characterized in that When analyzing the anti-cracking performance of the lining concrete based on the numerical simulation results, the vertical stress of the lining concrete at different temperatures when the lining concrete is put into the mold is compared to determine the influence of the concrete entering the mold temperature on the anti-cracking performance of the lining concrete.

8. A method for analyzing the risk of cracking of the inner lining concrete of a corrugated steel web box girder as claimed in claim 1, characterized in that When analyzing the anti-cracking performance of lining concrete based on numerical simulation results, the vertical stress of lining concrete under different convection coefficients on the surface of lining concrete is compared to determine the influence of surface convection coefficient on the anti-cracking performance of lining concrete, and then determine the influence of concrete surface insulation measures on the anti-cracking performance of lining concrete.

9. A method for analyzing cracking risk of lined concrete of a corrugated steel web box girder as claimed in claim 1, characterized in that: The process of determining the cracking risk of the target corrugated steel web lining concrete under the target environment includes: according to the influence of various considerations and combined with the numerical simulation results, determining whether the target corrugated steel web lining concrete has a cracking risk under the use environment of the target area, the set concrete mold temperature, and the proposed concrete surface insulation measures.

10. A system for analyzing the risk of cracking of the inner lining concrete of a corrugated steel web box girder, characterized in that: include: The model simulation module is configured to set displacement boundary conditions and temperature boundary conditions, establish a corrugated steel web lining concrete model, perform numerical calculations on the corrugated steel web lining concrete model, and analyze the numerical calculation results; The impact analysis module is configured to analyze the impact of various factors on the cracking risk of the corrugated steel web lining concrete based on the numerical calculation results, taking shrinkage effect, creep, concrete mold entry temperature and concrete surface insulation measures as considerations; The parameter adjustment module is configured to calculate the influence of shrinkage and creep effects on the crack resistance of the lining concrete according to the influence of various considerations during the design stage of the lining concrete of the corrugated steel web box girder, and then adjust the relevant design parameters. During the construction stage of the lining concrete of the corrugated steel web box girder, the concrete mold entry temperature is adjusted and the concrete surface insulation treatment is performed.

Images