Determination of construction parameters and construction method of intermediate supports at end supports of steel truss bridges

Abstract

The present application relates to a method for determining the construction parameters of the intermediate support of the end support of a steel truss bridge and a construction method, which constructs a finite element model of the entire bridge; applies a preset constant load to obtain the reaction force T0 of the intermediate support of the end support under the action of the constant load; applies a preset live load and additional force to obtain the maximum reaction force T1 and the minimum reaction force T2 of the intermediate support of the end support under the action of the live load and additional force; deletes the intermediate support of the end support, applies a downward unit force F in the middle of the end beam, and obtains the deflection δ in the span of the end beam under the action of F; based on T0, T1, T2, F and δ, obtains the construction parameters of the intermediate support of the end support. The present application conveniently obtains the construction parameters of the intermediate support of the end support, guides the installation and construction of the intermediate support of the end support, and makes the main constant load borne by the side support of the end support, thereby maximizing the reaction reserve of the end support or minimizing the pressure weight of the end support, and ensuring that the intermediate support of the end support has a good service life and bearing capacity.

Description

Technical Field

[0001] The present application relates to the technical field of bridge construction, and in particular to a method for determining construction parameters of an intermediate support at an end support point of a steel truss bridge and a construction method. Background Art

[0002] For two-main-truss railway steel truss bridges (including various bridge types such as suspension bridges, cable-stayed bridges, and arch bridges with steel truss main beams), when the lower layer is a two-track railway, the truss width is approximately 15m, which can meet the railway driving requirements of the lower layer. However, when the lower layer is a four-track railway, or a two-track railway + a highway or sidewalk, the truss width should generally be 30-40m to meet the driving requirements of the lower layer.

[0003] When the girder width is wide, in order to reduce the impact of temperature load on the train track, increase the vertical stiffness of the end cross beam, reduce the vertical displacement of the end cross beam under live load, and protect the beam end telescopic adjuster, a vertical end support intermediate support can be set in the middle of the end cross beam.

[0004] The middle support of this end support is generally a longitudinal movable support. Its main function is to limit the lateral displacement of the main beam and reduce the vertical displacement of the end beam under the action of live load. Therefore, its vertical direction generally only bears live load.

[0005] The installation of the middle support at the end support point is also a difficult problem.

[0006] If the middle support of the end support point is installed when the second phase of constant load construction is completed and no other measures are taken, the middle support of the end support point is likely to generate negative reaction force under the action of live load and additional force, affecting its service life.

[0007] If the middle support of the end support is installed directly before the completion of the second phase of constant load construction, the middle support of the end support may bear too much constant load, resulting in insufficient bearing capacity or insufficient constant load reaction reserve of the side support of the end support in the middle of the end beam.

[0008] Therefore, obtaining the relevant construction parameters of the intermediate support of the end support, such as the minimum vertical bearing capacity value and the lifting height of the end beam during installation, and using the relevant construction parameters to construct the intermediate support of the end support to ensure the life and other performance of the intermediate support of the end support, as well as ensuring sufficient constant load reaction force reserve of the side support of the end support, has become the key point of the installation of the intermediate support of the end support. However, there is currently no relevant report on how to obtain the relevant construction parameters of the intermediate support of the end support. Summary of the Invention

[0009] The embodiment of the present application provides a method for determining the construction parameters of the intermediate support of the end support of a steel truss bridge and a construction method. The relevant construction parameters of the intermediate support of the end support can be obtained more conveniently to guide the installation and construction of the intermediate support of the end support. The main constant load is borne by the side support of the end support, thereby maximizing the reaction reserve of the end support or minimizing the pressure weight of the end support, ensuring that the intermediate support of the end support has a good service life and bearing capacity.

[0010] In a first aspect, a method for determining construction parameters of intermediate supports at end supports of a steel truss bridge is provided, comprising:

[0011] Constructing a finite element model of the entire bridge, the finite element model comprising an end support and an intermediate support located between the end beam and the side pier;

[0012] Apply a preset constant load to obtain the reaction force of the middle support at the lower end support point under the action of the constant load;

[0013] Apply preset live load and additional force to obtain the maximum reaction force and minimum reaction force of the middle support of the lower end support under the action of the live load and additional force;

[0014] Deleting the middle supports of the end supports in the full-bridge finite element model, and applying a downward unit force in the middle of the end beam to obtain the deflection of the end beam in the middle of the span under the unit force;

[0015] Based on the reaction force of the middle support of the end support under the action of constant load, the maximum reaction force and minimum reaction force, unit force and deflection of the middle support of the end support under the action of live load and additional force, the construction parameters of the middle support of the end support are obtained. The construction parameters include the design value of the vertical minimum bearing capacity of the middle support of the end support and the lifting height of the end beam during installation.

[0016] In some embodiments, the lifting height h of the end beam during installation is calculated using a first formula, which includes:

[0017]

[0018] Where T2 is the minimum reaction force of the middle support of the end support under the action of live load and additional force, F is the downward unit force applied in the middle of the end beam, and δ is the deflection of the end beam in the middle of the span under the action of unit force F.

[0019] In some embodiments, the design value T of the vertical minimum bearing capacity of the intermediate support at the end support is calculated using a second formula, which includes:

[0020] T=T0+T1-T2

[0021] Among them, T0 is the reaction force of the middle support of the lower end support under the action of constant load, T1 is the maximum reaction force of the middle support of the lower end support under the action of live load and additional force, and T2 is the minimum reaction force of the middle support of the lower end support under the action of live load and additional force.

[0022] In some embodiments, the maximum reaction force T1 of the middle support of the lower end support under the action of live load and additional force is greater than 0, and the minimum reaction force T2 of the middle support of the lower end support under the action of live load and additional force is less than 0.

[0023] In a second aspect, a system for determining construction parameters of intermediate supports at end supports of a steel truss bridge is provided, comprising:

[0024] The first module is used to: construct a finite element model of the entire bridge, wherein the finite element model of the entire bridge includes an end support and an intermediate support located between the end cross beam and the side pier;

[0025] The second module is used to: apply a preset constant load to obtain the reaction force of the middle support of the lower end support under the constant load; apply a preset live load and additional force to obtain the maximum reaction force and minimum reaction force of the middle support of the lower end support under the live load and additional force;

[0026] The third module is used to: delete the middle support of the end support in the finite element model of the full bridge, and apply a downward unit force in the middle of the end beam to obtain the deflection of the end beam in the middle of the span under the unit force;

[0027] The fourth module is used to obtain the construction parameters of the middle support of the end support based on the reaction force of the middle support of the end support under the action of constant load, the maximum reaction force and minimum reaction force, unit force and deflection of the middle support of the end support under the action of live load and additional force. The construction parameters include the design value of the vertical minimum bearing capacity of the middle support of the end support and the lifting height of the end beam during installation.

[0028] In some embodiments, the lifting height h of the end beam during installation is calculated using a first formula, which includes:

[0029]

[0030] Where T2 is the minimum reaction force of the middle support of the end support under the action of live load and additional force, F is the downward unit force applied in the middle of the end beam, and δ is the deflection of the end beam in the middle of the span under the action of unit force F.

[0031] In some embodiments, the design value T of the vertical minimum bearing capacity of the intermediate support at the end support is calculated using a second formula, which includes:

[0032] T=T0+T1-T2

[0033] Among them, T0 is the reaction force of the middle support of the lower end support under the action of constant load, T1 is the maximum reaction force of the middle support of the lower end support under the action of live load and additional force, and T2 is the minimum reaction force of the middle support of the lower end support under the action of live load and additional force.

[0034] In some embodiments, the maximum reaction force T1 of the middle support of the lower end support under the action of live load and additional force is greater than 0, and the minimum reaction force T2 of the middle support of the lower end support under the action of live load and additional force is less than 0.

[0035] In a third aspect, a method for constructing an intermediate support at a steel truss bridge end point is provided, comprising:

[0036] After completing the installation of the end support side supports below the end crossbeam, lift the end crossbeam at the installation position of the end support middle support;

[0037] Install the end support middle support at the installation position of the end support middle support;

[0038] Release the end crossbeam to sit on the middle support of the end support point;

[0039] Among them, the end cross beam lifting height h and the vertical minimum bearing capacity design value of the end support intermediate support are obtained by using any of the above-mentioned methods for determining the construction parameters of the end support intermediate support of the steel truss bridge.

[0040] In some embodiments, the steel truss bridge is a beam bridge, a suspension bridge, a cable-stayed bridge, a cable-stayed-suspension coordinated system bridge, or an arch bridge whose main beams are steel trusses.

[0041] The beneficial effects of the technical solution provided by this application include:

[0042] The embodiment of the present application provides a method for determining the construction parameters and construction method of the intermediate support of the end support of a steel truss bridge. The present application uses a finite element model to simulate the stress conditions during the actual construction process, and calculates the vertical minimum bearing capacity design value of the intermediate support of the end support and the lifting height of the end cross beam during installation to guide the installation and construction of the intermediate support of the end support. The main constant load is borne by the side support of the end support, which maximizes the reaction reserve of the end support or minimizes the pressure weight of the end support, ensuring that the intermediate support of the end support has a good service life and bearing capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0044] Figure 1A schematic diagram of a typical two-main-truss five-span continuous beam restraint system provided in an embodiment of the present application;

[0045] Figure 2 This is a layout diagram of the end support middle support and end support side support provided in the embodiment of the present application.

[0046] In the figure: 1. End cross beam; 2. End support intermediate support; 3. End support side support; 4. Main tower pier; 5. Auxiliary pier; 6. Side pier; 7. Main truss centerline; 8. Bridge centerline. DETAILED DESCRIPTION

[0047] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0048] The steel truss bridge mentioned in this application includes a two-main-truss railway steel truss bridge.

[0049] The main beam of the double-main-truss railway steel truss bridge adopts a steel truss beam, which can be a beam bridge, a suspension bridge, a cable-stayed bridge, a cable-stayed-suspension coordinated system bridge or an arch bridge.

[0050] For example, see Figure 1 As shown in FIG, a typical two-main-truss five-span continuous beam restraint system is provided, which includes two main tower piers 4, two auxiliary piers 5 and two side piers 6, as well as two main-truss center lines 7 and the bridge center line 8. Three supports are provided at the side piers 6, as shown in FIG. Figure 2 As shown, the three supports at the side pier 6 are respectively an end support middle support 2 and two end support side supports 3.

[0051] Since the main truss of the steel truss is the main force-transmitting component, the reaction force of the end support side support 3 is usually much greater than the reaction force of the end support middle support 2.

[0052] Typically, five-span continuous cable-stayed bridges, cable-stayed and suspension bridges, or suspension bridges have a low reaction reserve under dead load at the end supports. In some cases, negative reaction forces may occur at the end supports under the action of primary loads, necessitating additional weighting. To increase the pressure reserve of the end support or reduce the additional weight, the reaction force sharing between the intermediate and side supports of the end supports is determined, and then the intermediate supports are installed.

[0053] Before installation, it is necessary to determine the construction parameters of the end supports and intermediate supports, and the method provided in this application can be used specifically.

[0054] The embodiment of the present application provides a method for determining construction parameters of an intermediate support at a steel truss bridge end point, characterized in that the method includes:

[0055] 101: Construct a finite element model of the entire bridge, wherein the finite element model of the entire bridge includes an end support intermediate support 2 located between an end cross beam 1 and a side pier.

[0056] At this time, the end cross beam 1 does not need to be lifted, that is, the lifting height h of the end cross beam 1 is 0.

[0057] 102: Apply a preset constant load to obtain the reaction force T0 of the middle support 2 of the lower end support under the action of the constant load; apply a preset live load and additional force to obtain the maximum reaction force T1 and the minimum reaction force T2 of the middle support 2 of the lower end support under the action of the live load and the additional force.

[0058] In step 102, dead load (including ballast), live load, additional force, etc. are applied according to regulations, and construction phases are established according to the subsequent actual construction process.

[0059] It will be appreciated that the aforementioned preset dead load, live load, and additional force are known in advance because the entire actual bridge construction process is known. Therefore, the dead load, live load, and additional force required to be applied during construction are also known, namely, the aforementioned preset dead load, live load, and additional force. In step 102, the previously known dead load, live load, and additional force are applied to the finite element model to reproduce the actual bridge construction conditions. This ensures that the reaction forces associated with the end supports and intermediate supports 2 obtained in the finite element model are close to the reaction forces generated during the subsequent actual bridge construction process.

[0060] 103: Delete the middle support 2 of the end support in the full bridge finite element model, apply a downward unit force F to the middle of the end cross beam 1, and obtain the deflection δ of the mid-span of the end cross beam 1 under the action of the unit force F.

[0061] 104: Based on the reaction force T0 of the end support middle support 2 under the action of constant load, the maximum reaction force T1 and the minimum reaction force T2 of the end support middle support 2 under the action of live load and additional force, the unit force F and the deflection δ, the construction parameters of the end support middle support 2 are obtained, and the construction parameters include the design value of the vertical minimum bearing capacity of the end support middle support 2 and the lifting height of the end cross beam 1 during installation.

[0062] The lifting height h of the end beam 1 during installation is calculated using the first formula, which includes:

[0063]

[0064] Where T2 is the minimum reaction force of the middle support 2 of the end support under the action of live load and additional force, F is the downward unit force applied in the middle of the end cross beam 1, and δ is the deflection of the end cross beam 1 in the middle of the span under the action of unit force F.

[0065] The design value T of the vertical minimum bearing capacity of the intermediate support 2 at the end support is calculated using the second formula, which includes:

[0066] T=T0+T1-T2

[0067] Among them, T0 is the reaction force of the middle support 2 of the lower end support under the action of constant load, T1 is the maximum reaction force of the middle support 2 of the lower end support under the action of live load and additional force, and T2 is the minimum reaction force of the middle support 2 of the lower end support under the action of live load and additional force.

[0068] It can be understood that the maximum reaction force T1 of the middle support 2 at the lower end support under the action of live load and additional force is greater than 0, that is, T1>0, and the minimum reaction force T2 of the middle support 2 at the lower end support under the action of live load and additional force is less than 0, that is, T2<0.

[0069] It can be seen that this application uses a finite element model to simulate the stress conditions during the actual construction process, and calculates the vertical minimum bearing capacity design value of the end support middle support 2 and the lifting height of the end beam 1 during installation to guide the installation and construction of the end support middle support. The main constant load is borne by the end support side support, which maximizes the reaction reserve of the end support or minimizes the pressure weight of the end support, ensuring that the end support middle support has a good service life and bearing capacity.

[0070] Based on the above-mentioned method for determining the construction parameters of the intermediate support of the steel truss bridge end support, the embodiment of the present application further provides a system for determining the construction parameters of the intermediate support of the steel truss bridge end support, which includes a first module, a second module, a third module and a fourth module, wherein:

[0071] The first module is used to construct a finite element model of the entire bridge, which includes an end support intermediate support 2 located between the end cross beam 1 and the side pier.

[0072] The second module is used to: apply a preset constant load to obtain the reaction force T0 of the middle support 2 of the lower end support under the action of the constant load; apply a preset live load and additional force to obtain the maximum reaction force T1 and minimum reaction force T2 of the middle support 2 of the lower end support under the action of the live load and additional force.

[0073] The third module is used to: delete the middle support 2 of the end support in the full-bridge finite element model, and apply a downward unit force F in the middle of the end crossbeam 1 to obtain the deflection δ of the mid-span of the end crossbeam 1 under the action of the unit force F.

[0074] The fourth module is used to obtain the construction parameters of the end support intermediate support 2 based on the reaction force T0 of the end support intermediate support 2 under the action of constant load, the maximum reaction force T1 and minimum reaction force T2 of the end support intermediate support 2 under the action of live load and additional force, unit force F and deflection δ. The construction parameters include the design value of the vertical minimum bearing capacity of the end support intermediate support 2 and the lifting height of the end cross beam 1 during installation.

[0075] The present application also provides a method for constructing an intermediate support at a steel truss bridge end support, which includes:

[0076] 201: After completing the installation of the end support side support 3 below the end cross beam 1, the end cross beam 1 is lifted up by h at the installation position of the end support middle support 2. The lifting height h of the end cross beam 1 is obtained by the above-mentioned method for determining the construction parameters of the end support middle support of the steel truss bridge.

[0077] Before step 201 , the bridge superstructure and auxiliary structures have been installed.

[0078] In step 201, only the end support side supports 3 are installed, and the end support middle supports 2 are not installed temporarily.

[0079] 202: Install the end support intermediate support 2 at the installation position of the end support intermediate support 2, wherein the vertical minimum bearing capacity design value of the selected end support intermediate support 2 is obtained by the above-mentioned method for determining the construction parameters of the end support intermediate support of the steel truss bridge.

[0080] Specifically, after the end support and the intermediate support 2 are placed, grouting is performed to fix them.

[0081] 203: Remove the lifting device and release the end crossbeam 1 to sit on the middle support 2 of the end support and the side support 3 of the end support.

[0082] Example

[0083] Take a cable-stayed-suspension bridge as an example. Figure 1 and Figure 2 As shown, the bridge is a typical two-main-truss five-span continuous beam restraint system. The longitudinal span of the main beam is arranged as 126m+131m+988m+131m+126m, and the beam width W=35m.

[0084] Since the main truss of the steel truss is the main force-transmitting component, the reaction force of the end support side support is usually much greater than that of the end support middle support.

[0085] Typically, five-span continuous cable-stayed bridges, cable-stayed and suspension bridges, or suspension bridges have a low reaction reserve under dead load at the end supports. In some cases, negative reaction forces may occur at the end supports under the action of primary loads, necessitating additional weighting. To increase the pressure reserve of the end support or reduce the additional weight, clarify the reaction force sharing between the end support intermediate supports and the end support side supports, and adopt the following installation method for the end support intermediate supports.

[0086] S1: Construction of the bridge superstructure and accessories, installation of all bearings, but not the middle bearing 2 at the end support.

[0087] S2: At the middle support 2 of the end support point, lift the end cross beam 1 by Δ and maintain the lifting height unchanged.

[0088] S3: Install the middle support 2 of the end support and fix it with grouting.

[0089] S4: Release the lifting device at the middle support of the end support, and the installation of the middle support 2 of the end support is completed.

[0090] In the above step S2, the end cross beam 1 is lifted up and then the end support intermediate support 2 is installed. This is mainly to reserve a certain amount of pressure for the end support intermediate support 2 to ensure that no negative reaction force occurs in the support during the operation phase.

[0091] In the above step S2, the height Δ of the end cross beam 1 and the vertical minimum bearing capacity design value T of the end support intermediate support 2 are determined according to the following method.

[0092] S21: Establish a finite element model of the entire bridge. The dead load (including ballast), live load, additional force, etc. are applied according to regulations. The construction phase is established according to the above-mentioned construction process, in which the end cross beam 1 is temporarily not lifted.

[0093] S22: Read the support reaction force under various loads. The reaction force of the middle support 2 at the lower end support under a dead load is T0, the maximum reaction force of the middle support 2 at the lower end support under a live load and additional forces is T1, and the minimum reaction force of the middle support 2 at the lower end support under a live load and additional forces is T2 (T2 should be less than 0).

[0094] S23: In the finite element model of the full bridge, delete the middle support 2 at the end support, and apply a downward unit force F to the middle of the end cross beam 1. Read the deflection δ in the mid-span of the end cross beam 1 under the action of force F.

[0095] S24: Calculate the construction parameters of the middle support 2 of the end support.

[0096] Among them, the design value of the vertical minimum bearing capacity of the end support and intermediate support 2 is T=T0+T1-T2.

[0097] The lifting height of the end beam 1 during installation

[0098] It is known that in step S21, T0=0, T1=3549 kN, and T2=-836 kN.

[0099] In step S23 , when F=1 kN, δ=0.00672 mm.

[0100] From this we can get T = 0 + 3549 + 836 = 4385 kN.

[0101]

[0102] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0103] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0104] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for determining the construction parameters of the intermediate supports at the end supports of a steel truss bridge, characterized in that: It includes: Constructing a full-bridge finite element model, the full-bridge finite element model comprising an end support intermediate support (2) located between the end cross beam (1) and the side pier; Applying a preset constant load to obtain the reaction force of the middle support (2) at the lower end support point under the action of the constant load; Applying a preset live load and additional force to obtain a maximum reaction force and a minimum reaction force of the middle support (2) at the lower end support point under the action of the live load and additional force; the maximum reaction force T1 of the middle support (2) at the lower end support point under the action of the live load and additional force is greater than 0, and the minimum reaction force T2 of the middle support (2) at the lower end support point under the action of the live load and additional force is less than 0; Deleting the middle support (2) of the end support in the full bridge finite element model, and applying a downward unit force in the middle of the end cross beam (1), and obtaining the deflection of the end cross beam (1) in the mid-span under the unit force; Based on the reaction force of the end support middle support (2) under the action of a constant load, the maximum reaction force and the minimum reaction force, the unit force and the deflection of the end support middle support (2) under the action of a live load and an additional force, the construction parameters of the end support middle support (2) are obtained, and the construction parameters include the design value of the vertical minimum bearing capacity of the end support middle support (2) and the lifting height of the end cross beam (1) during installation.

2. The method for determining construction parameters of the intermediate support at the end support of a steel truss bridge according to claim 1, characterized in that: During installation, the lifting height h of the end beam (1) is calculated using a first formula, which includes: Wherein, T2 is the minimum reaction force of the middle support (2) of the end support under the action of live load and additional force, F is the downward unit force applied in the middle of the end beam (1), and δ is the deflection of the end beam (1) at the mid-span under the action of unit force F.

3. The method for determining construction parameters of the intermediate support at the end support of a steel truss bridge according to claim 1, characterized in that: The design value T of the vertical minimum bearing capacity of the intermediate support (2) at the end support is calculated using the second formula, which includes: T=T0+T1-T2 Wherein, T0 is the reaction force of the middle support (2) of the lower end support under the action of the constant load, T1 is the maximum reaction force of the middle support (2) of the lower end support under the action of the live load and the additional force, and T2 is the minimum reaction force of the middle support (2) of the lower end support under the action of the live load and the additional force.

4. A system for determining construction parameters of intermediate supports at the end supports of a steel truss bridge, characterized in that: It includes: The first module is used to: construct a full-bridge finite element model, wherein the full-bridge finite element model includes an end support intermediate support (2) located between the end cross beam (1) and the side pier; The second module is used to: apply a preset constant load to obtain the reaction force of the lower end support middle support (2) under the action of the constant load; apply a preset live load and an additional force to obtain the maximum reaction force and the minimum reaction force of the lower end support middle support (2) under the action of the live load and the additional force; the maximum reaction force T1 of the lower end support middle support (2) under the action of the live load and the additional force is greater than 0, and the minimum reaction force T2 of the lower end support middle support (2) under the action of the live load and the additional force is less than 0; The third module is used to: delete the middle support (2) of the end support in the finite element model of the full bridge, and apply a downward unit force to the middle of the end beam (1) to obtain the deflection of the end beam (1) in the mid-span under the action of the unit force; The fourth module is used to obtain the construction parameters of the end support intermediate support (2) based on the reaction force of the end support intermediate support (2) under the action of the constant load, the maximum reaction force and the minimum reaction force, the unit force and the deflection of the end support intermediate support (2) under the action of the live load and the additional force, the construction parameters including the design value of the vertical minimum bearing capacity of the end support intermediate support (2) and the lifting height of the end cross beam (1) during installation.

5. The system for determining construction parameters of intermediate supports at the end supports of a steel truss bridge according to claim 4, characterized in that: During installation, the lifting height h of the end beam (1) is calculated using a first formula, which includes: Wherein, T2 is the minimum reaction force of the middle support (2) of the end support under the action of live load and additional force, F is the downward unit force applied in the middle of the end beam (1), and δ is the deflection of the end beam (1) at the mid-span under the action of unit force F.

6. The system for determining construction parameters of intermediate supports at the end supports of a steel truss bridge according to claim 4, characterized in that: The design value T of the vertical minimum bearing capacity of the intermediate support (2) at the end support is calculated using the second formula, which includes: T=T0+T1-T2 Wherein, T0 is the reaction force of the middle support (2) of the lower end support under the action of the constant load, T1 is the maximum reaction force of the middle support (2) of the lower end support under the action of the live load and the additional force, and T2 is the minimum reaction force of the middle support (2) of the lower end support under the action of the live load and the additional force.

7. A method for constructing an intermediate support at the end support of a steel truss bridge, characterized in that: It includes: After completing the installation of the end support side support (3) below the end cross beam (1), the end cross beam (1) is lifted up at the installation position of the end support middle support (2); Installing the end support point intermediate support (2) at the installation position of the end support point intermediate support (2); Release the end crossbeam (1) to seat on the middle support (2) of the end support point; The lifting height h of the end cross beam (1) and the design value of the vertical minimum bearing capacity of the end support intermediate support (2) are obtained by adopting the method for determining the construction parameters of the end support intermediate support of the steel truss bridge as described in any one of claims 1 to 3.

8. The method for constructing an intermediate support at a steel truss bridge end point according to claim 7, wherein: The steel truss bridge is a beam bridge, a suspension bridge, a cable-stayed bridge, a cable-stayed-suspension coordinated system bridge or an arch bridge whose main beams are steel trusses.

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