Construction control and operation and maintenance evaluation method for large-span continuous rigid frame bridge

Abstract

The invention discloses a construction control and operation and maintenance evaluation method for a large-span continuous rigid frame bridge, and belongs to the technical field of bridge construction management. The method comprises four parts of construction stage pre-camber prediction, box girder bottom plate pre-stress state evaluation, construction stage box girder internal force state analysis and rigid frame bridge operation and maintenance state evaluation considering concrete creep. The method comprises the following specific steps: firstly, establishing a large-span continuous rigid frame bridge mechanical model according to bridge mechanical characteristics and material characteristics; secondly, considering short-term shrinkage of concrete, and evaluating a box girder bottom plate steel wire bundle prestress state and a box girder internal force state; thirdly, predicting the pre-camber of the cantilever assembly bridge forming state, and putting forward construction control measures according to the pre-camber; and finally, considering the long-term creep effect of the concrete, and evaluating the long-term operation and maintenance state bridge line shape. According to the construction control and operation and maintenance evaluation method for the large-span continuous rigid frame bridge, a control scheme is provided for construction and operation and maintenance of the large-span continuous rigid frame bridge.

Description

Technical Field

[0001] The invention relates to the technical field of bridge construction management, and in particular to a method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge. Background Art

[0002] Large-span continuous rigid frame bridges are an important form of bridges that span deep valleys. The main span of this type of bridge is usually around 150 to 200 meters. It has the characteristics of smooth linear shape and stable formation. It is the main form of transportation structure in western China. However, the secondary internal forces of continuous rigid frame bridges are relatively complex, which is an inevitable result of ensuring the smooth linear shape of the bridge; and because the concrete structure has a large deadweight, the prestressed state varies greatly at different construction stages, making it difficult to control the linear shape of the bridge. Although the existing methods take into account the shrinkage and creep characteristics of concrete, it is still difficult to achieve accurate evaluation efficiently in the face of the actual construction and operation and maintenance needs of large-span continuous rigid frame bridges. Summary of the invention

[0003] The purpose of the present invention is to provide a method for construction control and operation and maintenance evaluation of a large-span continuous rigid frame bridge, introduce the short-term shrinkage and long-term creep of concrete into the constitutive matrix of the bridge, mainly use positive analysis, and predict the pre-arch degree of the large-span continuous rigid frame bridge in the construction stage based on the displacement difference before and after the system conversion, and propose bridge construction measures accordingly, and evaluate the bridge line shape in the long-term operation and maintenance status to ensure driving stability, so as to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge comprises the following steps:

[0006] S1: Mechanical model of long-span continuous rigid frame bridge;

[0007] S2: Prediction of pre-camber during construction stage;

[0008] S3: Assessment of prestress state of box girder bottom plate;

[0009] S4: Analysis of internal force state of box girder during construction stage;

[0010] S5: Rigid frame bridge operation and maintenance status assessment.

[0011] Furthermore, the specific steps of S1 are: using the principle of construction mechanics, a mechanical model of a long-span continuous rigid frame bridge is established, in which it is assumed that the bridge is in a static equilibrium state at each construction stage, and the short-term shrinkage characteristic data of concrete is included in the constitutive matrix of the box girder unit.

[0012] Furthermore, the specific steps of S2 are: before and after the bridge is closed, the structural system conversion characteristics are considered, and the pre-arch degree of the long-span continuous rigid frame bridge during the construction phase is predicted based on the displacement difference before and after the system conversion.

[0013] Furthermore, the specific steps of S3 are: with the goal of controlling the cracking of the box girder bottom slab concrete, analyzing the prestressing values ​​of the bottom slab steel wire bundles at different cantilever construction stages.

[0014] Furthermore, the specific steps of S4 are: with the goal of preventing sudden changes in the bending moment of the box girder, analyzing the internal force state of the box girder at different cantilever construction stages, and formulating construction control measures based on the prediction results.

[0015] Furthermore, the specific steps of S5 are as follows: on the basis of the mechanical model of the construction stage, the creep effect of concrete is introduced to evaluate the alignment of the bridge in the long-term operation and maintenance status to ensure driving stability.

[0016] Furthermore, the specific steps are as follows: first, a mechanical model of a large-span continuous rigid frame bridge is established based on the mechanical characteristics and material properties of the bridge; second, the short-term shrinkage of concrete is considered to evaluate the prestressed state of the steel wire bundles in the bottom plate of the box girder and the internal force state of the box girder; then, the pre-arch degree of the cantilever assembled bridge is predicted, and construction control measures are proposed accordingly; finally, the long-term creep effect of concrete is considered to evaluate the bridge line shape in the long-term operation and maintenance state.

[0017] Furthermore, based on the short-term shrinkage and long-term creep characteristics of concrete, the constitutive matrix of the rigid frame bridge is modified to form a time-varying mechanical model of the large-span continuous rigid frame bridge, and a construction control and operation and maintenance evaluation model is established.

[0018] Furthermore, the continuity of construction control and operation and maintenance evaluation; on the one hand, considering the short-term shrinkage of concrete, the stress state of the reinforcement tendons in the bottom plate of the box girder of the rigid frame bridge and the internal force characteristics of the box girder are predicted, and then the structural pre-arch at the moment of cantilever construction is analyzed, and construction control measures are proposed accordingly; on the other hand, the creep effect of concrete is introduced to evaluate the bridge line shape in the long-term operation and maintenance status to ensure driving stability; through the above-mentioned status evaluation, the applicability and safety of large-span continuous rigid frame bridges in the construction and operation and maintenance stages are guaranteed.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. Based on the shrinkage characteristics of concrete and the displacement difference before and after the conversion of the bridge system, the present invention establishes a construction mechanics model of a large-span continuous rigid frame bridge. Through positive analysis, the pre-arch degree, prestress of the steel wire bundles in the bottom plate of the box beam and the internal force state in the construction stage are predicted, and reasonable construction measures are determined accordingly to ensure construction safety.

[0021] 2. The present invention takes into account the long-term creep characteristics of concrete. On the basis of the state prediction in the construction phase, it continues to carry out the linear evaluation of the long-term operation and maintenance state of the bridge. According to the evaluation results, it judges the potential deformation trend of the structure to ensure the driving smoothness of the long-term operation and maintenance stage of the large-span continuous rigid frame bridge and ensure the applicability of the structure.

[0022] 3. The present invention provides quantitative technical support for the overall control of large-span continuous rigid frame bridges through construction safety and long-term applicability evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flowchart of the implementation steps of the present invention;

[0024] Figure 2 This is a construction mechanics model diagram of a long-span continuous rigid frame bridge of the present invention;

[0025] Figure 3 It is a pre-camber diagram of the bridge in the completed state of the present invention;

[0026] Figure 4 It is the stress state diagram of the steel wire bundle of the box girder bottom plate of the present invention;

[0027] Figure 5 The bending moment diagram of the bridge at the closing moment of the present invention;

[0028] Figure 6 It is a line diagram of the bridge during the operation period of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] See also Figure 1-6 In an embodiment of the present invention, a method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge is provided, comprising the following steps:

[0031] S1: Mechanical model of long-span continuous rigid frame bridge;

[0032] S2: Prediction of pre-camber during construction stage;

[0033] S3: Assessment of prestress state of box girder bottom plate;

[0034] S4: Analysis of internal force state of box girder during construction stage;

[0035] S5: Rigid frame bridge operation and maintenance status assessment.

[0036] Taking a super-large bridge across the Yellow River under construction as an example, the operation steps of this embodiment are described. The bridge is 340 meters long, and the spans of each span are 90+160+90 meters respectively. It is a continuous rigid frame bridge. For a rigid frame bridge with such a span, there are problems of construction system conversion and pre-camber of the completed bridge.

[0037] Step 1: Assume that the bridge is in a static equilibrium state at each construction stage, that is, the overall static equilibrium equation of the bridge is

[0038] [K]{Δ}={F} (1)

[0039] In the above formula: K is the bridge stiffness matrix, Δ is the bridge displacement vector, and F is the gravity load.

[0040] The shrinkage creep time history parameters of concrete are:

[0041]

[0042] Where: tt s is the age of concrete and the age at which shrinkage begins; Ac is the cross-sectional area of ​​the component; u is the circumference of the section where the component is in contact with the air.

[0043] According to the principle of construction mechanics, a finite element model of a long-span continuous rigid frame bridge can be established, such as Figure 2 shown.

[0044] Step 2: Import the stress and strain relationship of concrete shrinkage creep into the constitutive matrix. The corresponding finite element stiffness matrix will also change. Consider the influence of concrete shrinkage creep on the unit stiffness matrix during the construction stage and the bridge completion stage, and then obtain the deformation difference of the bridge system conversion at different construction stages, and then predict the pre-camber during the construction stage.

[0045] Δ 成桥预拱度 =Δ 竣工梁端标高 -Δ 设计梁端标高 (3)

[0046] In the above formula, Δ is the bridge displacement vector, and the subscripts are the pre-camber of the completed bridge, the elevation of the completed beam end, and the elevation of the designed beam end. Figure 3 This is the result of the camber prediction for the completed bridge.

[0047] Step 3: To control the cracking of the box girder bottom slab concrete, based on the above construction mechanics principles, the prestressing values ​​of the bottom slab wire bundles at different cantilever construction stages can be analyzed, such as Figure 4 shown.

[0048] Step 4: To prevent sudden changes in box girder bending moment, analyze the internal force state of the box girder at different cantilever construction stages, such as Figure 5As shown. According to the above analysis results, after the concrete strength of the cantilever beam section of the bridge reaches the designed tension strength, the prestressed tendons should be tensioned in time, and the tensioning sequence of the prestressed tendons should meet the design and specification requirements. Prestressed construction should adopt a double control method, with stress control as the main method and elongation value as the verification method. Grouting should be carried out in time after tensioning is completed. The design strength of cement slurry should not be lower than the design strength of the beam section, and an appropriate amount of expansion agent should be added.

[0049] Step 5: Based on the mechanical model of the construction phase, evaluate the bridge alignment in the long-term operation and maintenance status to ensure driving stability, such as Figure 6 shown.

[0050] In summary: A method for construction control and operation and maintenance evaluation of a large-span continuous rigid frame bridge of the present invention comprises four parts: prediction of pre-arch in the construction stage, evaluation of the prestressed state of the box girder bottom plate, analysis of the internal force state of the box girder in the construction stage, and evaluation of the operation and maintenance state of the rigid frame bridge considering concrete creep. The specific steps are: first, a mechanical model of a large-span continuous rigid frame bridge is established based on the mechanical characteristics and material properties of the bridge; second, the short-term shrinkage of concrete is considered to evaluate the prestressed state of the steel wire bundles of the box girder bottom plate and the internal force state of the box girder; then, the pre-arch of the cantilever assembled bridge state is predicted, and construction control measures are proposed accordingly; finally, the long-term creep effect of concrete is considered to evaluate the bridge line shape in the long-term operation and maintenance state, so as to provide a control scheme for the construction and operation and maintenance of large-span continuous rigid frame bridges.

[0051] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge, characterized in that: The following steps are involved: S1: Mechanical model of long-span continuous rigid frame bridge; S2: Prediction of pre-camber during construction stage; S3: Assessment of prestress state of box girder bottom plate; S4: Analysis of internal force state of box girder during construction stage; S5: Rigid frame bridge operation and maintenance status assessment.

2. A method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge as claimed in claim 1, characterized in that: The specific steps of S1 are: using the principles of construction mechanics, a mechanical model of a long-span continuous rigid frame bridge is established. In this model, it is assumed that the bridge is in a static equilibrium state at each construction stage, and the short-term shrinkage characteristic data of concrete is included in the constitutive matrix of the box girder unit.

3. The method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge according to claim 1, characterized in that: The specific steps of S2 are: before and after the bridge is closed, the structural system conversion characteristics are considered, and based on the displacement difference before and after the system conversion, the pre-arch degree of the large-span continuous rigid frame bridge during the construction phase is predicted.

4. A method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge as claimed in claim 1, characterized in that: The specific steps of S3 are: with the goal of controlling the cracking of the box girder bottom slab concrete, the prestressing values ​​of the bottom slab steel wire bundles at different cantilever construction stages are analyzed.

5. The method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge according to claim 1, characterized in that: The specific steps of S4 are: with the goal of preventing sudden changes in the box girder bending moment, analyze the internal force state of the box girder at different cantilever construction stages, and formulate construction control measures based on the prediction results.

6. The method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge according to claim 1, characterized in that: The specific steps of S5 are: based on the mechanical model of the construction stage, the concrete creep effect is introduced to evaluate the bridge alignment in the long-term operation and maintenance status to ensure driving stability.

7. The method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge according to claim 1, characterized in that: The specific steps are as follows: first, a mechanical model of a large-span continuous rigid frame bridge is established based on the mechanical characteristics and material properties of the bridge; second, the short-term shrinkage of concrete is considered to evaluate the prestressed state of the steel wire bundles in the box girder bottom plate and the internal force state of the box girder; then, the pre-arch degree of the cantilever assembled bridge is predicted, and construction control measures are proposed accordingly; finally, the long-term creep effect of concrete is considered to evaluate the bridge line shape in the long-term operation and maintenance state.

8. The method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge according to claim 1, characterized in that: Based on the short-term shrinkage and long-term creep characteristics of concrete, the constitutive matrix of the rigid frame bridge is modified, a time-varying mechanical model of the large-span continuous rigid frame bridge is formed, and a construction control and operation and maintenance evaluation model is established.

9. The method for construction control and operation and maintenance evaluation of a long-span continuous rigid frame bridge according to claim 1, characterized in that: The continuity of construction control and operation and maintenance evaluation; on the one hand, considering the short-term shrinkage of concrete, predict the stress state of the reinforcement tendons in the bottom plate of the box girder of the rigid frame bridge and the internal force characteristics of the box girder, and then analyze the structural pre-arch at the moment of cantilever construction, and propose construction control measures accordingly; on the other hand, introduce the concrete creep effect, evaluate the bridge line shape in the long-term operation and maintenance status, and ensure driving stability; through the above-mentioned status evaluation, ensure the applicability and safety of the large-span continuous rigid frame bridge during the construction and operation and maintenance stages.

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