Asymmetrically loaded steel truss girder cable-stayed bridge side span closure construction control method

Abstract

The application discloses a kind of asymmetric load steel truss girder cable-stayed bridge side span closure construction control methods, it is characterized in that, include the following steps: S1, install the steel truss girder of store beam section on side pier;S2, adjust the upstream / downstream elevation of cantilever section steel truss girder to upstream / downstream elevation is located at the same level height;S3, closure section steel truss girder and cantilever section steel truss girder butt joint;S4, adjust the first elevation and first vertical angle of closure section steel truss girder and the butt joint end of store beam section steel truss girder, until it reaches design elevation and design vertical angle;S5, adjust the second elevation, second vertical angle, second lateral bending and second lateral angle of store beam section steel truss girder and the butt joint end of closure section steel truss girder, until it is respectively same with first elevation, first vertical angle, first lateral bending and first lateral angle;S6, butt joint store beam section steel truss girder and closure section steel truss girder, and closure is completed.The application has the advantages that keep steel truss girder smooth, reduce closure difficulty.

Description

Technical Field

[0001] This invention relates to the field of steel truss cable-stayed bridges. More specifically, this invention relates to a method for controlling the construction of a side span closure of a steel truss cable-stayed bridge under asymmetrical loads. Background Technology

[0002] With the continuous development of long-span steel truss cable-stayed bridges, bridge spans are also constantly being updated. In particular, double-deck steel truss cable-stayed bridges for both road and rail use have seen rapid development due to their superior traffic capacity. For example, the Shanghai-Nantong Yangtze River Bridge and the Changtai Yangtze River Bridge both have spans exceeding 1,000 meters. For multi-lane cable-stayed bridges for both road and rail use, the railway deck is usually located in the middle lane of the lower layer of the steel truss girder. The main girder maintains a symmetrical distribution of the primary and secondary dead loads upstream and downstream. This type of bridge has significant advantages in construction control. However, since the railway line is located in the middle of the bridge deck, the railway and highway usually need to be separated after crossing the bridge. This requires the design of specially designed ramps to allow the highway lanes on both sides of the railway line to converge. The design of these ramps inevitably occupies more land and leads to higher construction costs.

[0003] With the development of cable-stayed bridges for both railway and highway use in my country, the design is no longer limited to the railway line being located in the middle of the bridge deck. Instead, the railway and highway lanes are separated, with the upstream lane for railway and the downstream lane for highway, or vice versa. The advantage of this design is that after crossing the bridge, the railway and highway lines can be separated directly without the need for dedicated ramps, reducing land occupation. However, the upstream and downstream load distribution of this type of steel truss cable-stayed bridge is asymmetrical, with the dead load on the railway side typically being much larger than that on the highway. The asymmetrical transverse load and lateral stiffness of the main girder, along with the potential for height differences between the upstream and downstream sections, inevitably pose significant challenges to controlling the main girder alignment during construction. This is especially true at the closure section of the side spans, where there is a certain cable-free zone, increasing the difficulty of closure and making it difficult to guarantee closure accuracy. Summary of the Invention

[0004] Another objective of this invention is to provide a construction control method for the side span closure of a cable-stayed bridge under asymmetrical loads, which avoids the height difference between the upstream and downstream sides caused by asymmetrical loads, maintains the smoothness of the steel truss girder, and reduces the difficulty of closure.

[0005] To achieve these objectives and other advantages according to the present invention, a method for controlling the construction of the side span closure of an asymmetric load steel truss cable-stayed bridge is provided. This method involves connecting and closing the steel truss section located at the side span with the cantilever section located in the middle span using a closure segment steel truss. The side span closure construction control method includes the following steps:

[0006] S1. Hoist the steel truss beam section to the top of the side pier and install it on the side pier;

[0007] S2. Tension the stay cables of the cantilever steel truss section to the target cable force, and adjust the upstream / downstream elevation of the cantilever steel truss section to the same horizontal level.

[0008] S3. Hoisting and connecting the closure section steel truss beam with the cantilever section steel truss beam;

[0009] S4. Adjust the first elevation and first vertical rotation angle of the connection end between the closure section steel truss and the storage section steel truss until they reach the design elevation and design vertical rotation angle; obtain the first lateral bending amount and first lateral rotation angle of the connection end between the closure section steel truss and the storage section steel truss.

[0010] S5. Adjust the second elevation, second vertical rotation angle, second lateral deflection, and second lateral rotation angle at the joint end of the steel truss girder of the storage section and the steel truss girder of the closure section, so that they are the same as the first elevation, first vertical rotation angle, first lateral deflection, and first lateral rotation angle, respectively.

[0011] S6. Connect the steel truss girder of the storage section and the steel truss girder of the closure section, and the closure is completed.

[0012] Preferably, in step S1, the initial installation position of the steel truss beam of the storage section on the side pier is a first distance pre-offset from its preset installation position to the side span.

[0013] Preferably, the first distance S satisfies the following relationship:

[0014] S≥ΔS1+ΔS2+ΔS3+ΔS4;

[0015] In the formula: ΔS1 is the intersection distance of the diagonal web members of adjacent steel truss segments; ΔS2 is the remaining amount of compression compensation for the steel truss; ΔS3 is the elongation of the steel truss segment due to temperature change; ΔS4 is the operating distance.

[0016] Preferably, in step S2, adjusting the upstream and downstream elevations of the cantilever steel truss section to be at the same horizontal level is based on the upstream / downstream elevation. The downstream / upstream elevation of the cantilever steel truss section is adjusted by adjusting the cable lengths of the downstream / upstream side stay cables. The specific adjustment process is as follows:

[0017] S21. Calculate the upstream and downstream weight deviations of multiple steel truss segments located in the cable-free zone; take the sum of the multiple weight deviations as the upstream and downstream weight deviation ΔG of the cantilever steel truss segment. i ;

[0018] S22, Based on the upstream and downstream weight deviation ΔG of the cantilever steel truss section i The difference ΔTi between the upstream and downstream cable forces of the cable to be adjusted is calculated using the following formula:

[0019]

[0020] S23. Obtain the cumulative elevation difference Δh between the upstream and downstream sections of the cantilever steel truss girder. i ;

[0021] S24. Based on the difference ΔTi between the upstream and downstream cable forces of the stay cable and the cumulative elevation difference Δh between the upstream and downstream sections of the cantilever steel truss girder. i The stress-free cable lengths of the upstream / downstream stay cables relative to the stress-free cable lengths of the downstream / upstream stay cables are calculated using the following formula:

[0022]

[0023] Where: xi—the difference between the longitudinal coordinate of the anchor point at the end of the cable-stayed tower and the longitudinal coordinate of the anchor point at the end of the beam;

[0024] yi — The difference between the x-coordinate of the anchor point at the end of the cable-stayed tower and the x-coordinate of the anchor point at the end of the beam, to be adjusted;

[0025] zi — The difference between the vertical coordinates of the anchor point at the cable tower end and the vertical coordinates of the anchor point at the beam end, to be adjusted;

[0026] E—the elastic modulus of the cable;

[0027] A—Effect cross-sectional area of ​​the cable-stayed cable;

[0028] q—Severity of the cable-stayed line;

[0029] S1i—is the unstressed cable length of the downstream / upstream stay cable;

[0030] S2i—is the stress-free cable length of the stay cable to be adjusted on the upstream / downstream side.

[0031] Preferably, in step S4, a jack is installed at the top of the auxiliary pier located below the cantilever steel truss section, and the first elevation and the first vertical rotation angle are adjusted to the design elevation and the design vertical rotation angle by means of the jack.

[0032] Preferably, in step S6, after adjusting the storage section steel truss to the preset installation position, the storage section steel truss and the closure section steel truss are connected to complete the side span closure construction.

[0033] The present invention has at least the following beneficial effects: by first adjusting the upstream and downstream of the cantilever steel truss section to have virtually no height difference, making it smooth, the present invention can facilitate the subsequent connection and closure of the stored steel truss section with the cantilever steel truss section through the closure section steel truss section, thus reducing the difficulty of closure.

[0034] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the cross-sectional structure of the cable-stayed bridge of the present invention;

[0036] Figure 2 This is a schematic diagram of step S3 of the present invention;

[0037] Figure 3 This is a schematic diagram of step S4 of the present invention;

[0038] Figure 4 for Figure 3 Enlarged view of A in the middle;

[0039] Figure 5 This is a schematic diagram of the steel truss segment of the present invention;

[0040] Explanation of reference numerals on the accompanying drawings:

[0041] 1. Main girder of cable-stayed bridge; 2. Closing section steel truss girder; 3. Storage section steel truss girder; 4. Cantilever section steel truss girder; 5. Side pier; 6. Side pier support; 7. Cable stays; 8. Lower chord; 9. Diagonal web members; 10. Upper chord; 11. Auxiliary pier; 12. First vertical corner; 13. Second vertical corner; 14. Bridge deck crane. Detailed Implementation

[0042] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0043] It should be noted that in the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0044] like Figure 1-5 As shown, this invention provides a method for controlling the construction of the side span closure of an asymmetric load steel truss cable-stayed bridge. The method involves connecting the existing steel truss section 3 at the side span with the cantilever steel truss section 4 at the middle span via the closure section steel truss 2. The side span closure construction control method includes the following steps:

[0045] S1. Hoist the steel truss beam section 3 to the top of the side pier 5 and install it on the side pier 5.

[0046] The crane vessel is anchored and positioned to transport the stored steel truss girder 3 to the side pier 5. The crane vessel is then used to lift the stored steel truss girder 3 to the top of the side pier 5 for initial installation. To ensure the stability of the stored steel truss girder 3 during installation, a side pier support 6 can be installed on the side wall of the side pier 5 to support the stored steel truss girder 3.

[0047] S2. Tension the stay cables 7 of the cantilever steel truss 4 to the target cable force, and adjust the upstream / downstream elevation of the cantilever steel truss 4 to the same horizontal level.

[0048] like Figure 1 As shown, if the upstream lane is a railway and the downstream lane is a highway, the weight on the upstream railway side is greater than that on the downstream highway side, and the center of gravity of the main girder 1 of the cable-stayed bridge is biased towards the upstream railway side; if the upstream lane is a highway and the downstream lane is a railway, the center of gravity of the section is biased towards the downstream railway. Therefore, there is asymmetry between the upstream and downstream sections of the steel truss girder segment, making closure difficult. In order to ensure smooth connection of the steel truss girder and reduce the difficulty of subsequent closure, the height difference between the upstream and downstream of the cantilever steel truss girder 4 is controlled to be Δh≈0 after the stay cables 7 of the cantilever steel truss girder 4 are tensioned, so that the upstream and downstream of the cantilever steel truss girder 4 are smooth. The "stress-free cable length" is used for control when the stay cables 7 are tensioned.

[0049] Adjusting the upstream and downstream elevations of the cantilever steel truss girder 4 to be at the same horizontal level is based on the on-site construction conditions. The upstream / downstream elevations are used as a reference, and the downstream / upstream elevations of the cantilever steel truss girder 4 are adjusted by adjusting the cable lengths of the downstream / upstream side stay cables 7. If the center of gravity of the section is biased upstream, the upstream elevation is adjusted based on the downstream elevation; if the center of gravity is biased downstream, the downstream elevation is adjusted based on the upstream elevation. The specific adjustment process is as follows:

[0050] S21. Calculate the upstream and downstream weight deviations of multiple steel truss segments located in the cable-free zone; take the sum of multiple weight deviations as the upstream and downstream weight deviation ΔG of the cantilever steel truss segment 4. i ΔG i This refers to the weight deviation that the cantilever section steel truss beam 4 and cable 7 need to overcome;

[0051] S22, Based on the upstream and downstream weight deviation ΔG of the cantilever steel truss section 4 i The difference ΔTi between the upstream and downstream cable forces of the cable to be adjusted (cable 7) is calculated using the following formula:

[0052]

[0053] S23. Measure and obtain the cumulative elevation difference Δh between the upstream and downstream sides of the cantilever steel truss girder 4. i ;

[0054] Before tensioning the 7-stayed cable, a level was used to measure the upstream and downstream elevations H1 and H2 of the lower chord at the joint between the cantilever section steel truss 4 and the closure section steel truss 2, respectively, i.e., the cumulative elevation difference Δh between the upstream and downstream sections. i =H1-H2;

[0055] S24. Based on the difference ΔTi between the upstream and downstream cable forces of cable 7 and the cumulative elevation difference Δh between the upstream and downstream sides of the cantilever steel truss girder 4. i The unstressed cable length of cable 7 on the upstream / downstream side is calculated relative to the unstressed cable length on the downstream / upstream side using the following formula:

[0056]

[0057] In the formula: xi—the difference between the longitudinal coordinate of the anchor point at the tower end of the cable-stayed cable 7 and the longitudinal coordinate of the anchor point at the beam end;

[0058] yi — The difference between the abscissa of the anchor point at the tower end of cable-stayed cable 7 and the abscissa of the anchor point at the beam end;

[0059] zi — The difference between the vertical coordinates of the anchor point at the cable tower end and the vertical coordinates of the anchor point at the beam end, to be adjusted;

[0060] E—The elastic modulus of cable 7;

[0061] A—Effective cross-sectional area of ​​cable-stayed bridge 7;

[0062] q—Heavy weight of cable-stayed bridge line 7;

[0063] S1i—is the length of the stress-free cable 7 of the downstream / upstream stay cable;

[0064] S2i—is the stress-free cable length of the cable 7 to be adjusted on the upstream / downstream side;

[0065] Based on the calculated stress-free cable length of cable 7, the cable length of the corresponding side cable 7 is adjusted to the calculated value, and the upstream and downstream elevation adjustments of the cantilever section steel truss beam 4 are completed.

[0066] S3. Hoisting and connecting the closure section steel truss beam 2 with the cantilever section steel truss beam 4;

[0067] like Figure 2As shown, the connection sequence between the closure section steel truss 2 and the cantilever section steel truss 4 is as follows: installation of the lower chord 8 → installation of the diagonal web members 9 → installation of the upper chord 10 → welding of the upper and lower bridge decks. The connection adjustment measures are as follows: the installation of the lower chord 8 is mainly achieved by adjusting the spatial posture of the closure section steel truss 2 using the lifting equipment of the bridge deck crane 14, so that the lower chord 8 of the closure section steel truss 2 and the lower chord 8 of the cantilever section steel truss 4 are properly aligned; during the installation of the diagonal web members 9, the connection is achieved by adjusting the lower chord 8 of the closure section steel truss 2 and the cantilever section steel truss 4. 4. Tie rods are installed on the upper chord 10 and the diagonal web members 9. Under the action of the hook of the bridge deck crane 14, the diagonal web members 9 are installed in conjunction with the tie rods. During the installation of the upper chord 10, the tie rods symmetrically arranged at the upper chord 10 are used to install the upper chord 10. Finally, the misalignment between the upper and lower bridge decks is adjusted by the clamping plate, and the bridge decks are welded. After all the high bolts and the upper and lower bridge decks are welded, the bridge deck crane 14 releases the hook, and the installation of the closure section steel truss 2 is completed.

[0068] S4. Adjust the first elevation and first vertical rotation angle 12 at the joint end of the closure section steel truss beam 2 and the storage section steel truss beam 3 until they reach the design elevation and design vertical rotation angle; obtain the first lateral bending amount and first lateral rotation angle at the joint end of the closure section steel truss beam 2 and the storage section steel truss beam 3; the design elevation and design vertical rotation angle are the target elevation and target vertical rotation angle for construction monitoring;

[0069] like Figure 3 , Figure 4 As shown, since the closure section steel truss is located in a cable-free zone, adjusting its first elevation and first vertical rotation angle 12 at the connection point with the storage section steel truss 3 is quite difficult. Therefore, the first elevation and first vertical rotation angle 12 are indirectly adjusted by adjusting the elevation and vertical rotation angle of the cantilever section steel truss 4, which is integrated with the closure section steel truss. Specifically, multiple vertical jacks are symmetrically installed between the auxiliary pier 11 and the cantilever section steel truss 4. The first elevation and first vertical rotation angle 12 are adjusted to the design elevation and design height by pushing with the vertical jacks. Calculate the vertical rotation angle; due to the asymmetry of the upstream and downstream cable forces of the cable-stayed bridge, the sum of the lateral horizontal components of the upstream and downstream cable forces is not zero. If the upstream / downstream cable forces are large, the lateral horizontal components of the upstream / downstream cable forces will be large, which will cause the steel beam to have a lateral bending amount and lateral rotation angle downstream / upstream. Therefore, in order to ensure the smooth connection of the beam segment at the closure section, it is also necessary to obtain the first lateral bending amount and the first lateral rotation angle at the connection end of the closure section steel truss beam 2 and the storage section steel truss beam 3, so as to guide and adjust the installation posture of the storage section steel truss beam 3.

[0070] S5. Adjust the second elevation, second vertical rotation angle 13, second lateral bending amount and second lateral rotation angle at the docking end of the steel truss beam 3 of the storage section and the steel truss beam 2 of the closure section, so that they are the same as the first elevation, first vertical rotation angle 12, first lateral bending amount and first lateral rotation angle respectively.

[0071] Multiple pads and multiple horizontal jacks are set on the top of the side pier 5 and the top of the side pier support 6. By adjusting the height of the pads, the second elevation and the second vertical rotation angle 13 are adjusted to be the same as the first elevation and the first vertical rotation angle 12, respectively. By adjusting the horizontal jacks, the second lateral bending amount and the second lateral rotation angle are adjusted to be the same as the first lateral bending amount and the first lateral rotation angle, respectively, so that the steel truss beam 3 of the beam storage section and the steel truss beam 2 of the closure section tend to be consistent, so as to ensure the subsequent closure accuracy. At the same time, the alignment of the two ends of the closure opening is re-measured. If there is a difference, the steel truss beam 3 of the beam storage section is further fine-tuned so that the axis and inclination angle of the lower chord 8 end are matched with the axis and inclination angle of the lower chord 8 of the steel truss beam 2 of the closure section.

[0072] S6. Connect the steel truss beam 3 of the storage section and the steel truss beam 2 of the closure section, and the closure is completed.

[0073] This invention establishes a cable adjustment mechanism by relating the asymmetric loads and cable forces between the upstream and downstream sections, ensuring that there is essentially no height difference between the upstream and downstream sections of the cantilever steel truss 4, maintaining smoothness. This facilitates the subsequent connection and closure of the storage section steel truss 3 with the cantilever steel truss 4 via the closure section steel truss 2, reducing the difficulty of closure in the cable-free zone. By adjusting the elevation and vertical rotation of the connection points of the closure section steel truss 2 and the storage section steel truss 3, the elevation, axis, and rotation on both sides of the closure joint of the side span are kept consistent, achieving the goal of rapid and precise closure of the steel truss segments in the cable-free zone of the side span.

[0074] In another technical solution, in step S1, the initial installation position of the steel truss beam 3 on the side pier 5 is a first distance pre-offset from its preset installation position to the side span; the first distance S satisfies the following relationship:

[0075] S≥ΔS1+ΔS2+ΔS3+ΔS4;

[0076] In the formula: ΔS1 is the intersection distance of the diagonal web members 9 of adjacent steel truss segments; ΔS2 is the remaining amount of compression compensation of the steel truss; ΔS3 is the elongation of the steel truss segment due to temperature change; ΔS4 is the operating distance.

[0077] In this technical solution, when initially installing the storage section steel truss girder 3, its installation position is pre-offset by a first distance S towards the side span to reserve space for lifting the closure section steel truss girder 2 in advance, avoiding obstruction by the storage section steel truss girder 3 during the lifting and installation of the closure section steel truss girder 2; where ΔS1 is the intersection distance of the diagonal web members 9 of the storage section steel truss girder 3 and the diagonal web members 9 of the closure section steel truss girder 2. When the steel truss girder segments are connected, the center lines of the diagonal web members 9 are aligned, but during the lifting of the girder segment, there may be a situation where the diagonal web members 9 intersect with the lower chord members 8 and diagonal web members 9 of the already erected girder segment, so this space must be reserved during lifting; for large-span steel truss cable-stayed bridges, after the bridge is completed, in the longitudinal direction of the cable stays 7 Under the action of the horizontal component force, the steel truss girder is subjected to longitudinal compression. Therefore, during the steel girder manufacturing stage, longitudinal compression compensation must be carried out. When the side span is closed, the initial tension of the cable 7 is about 60% to 70% of the cable force of the completed bridge. The remaining amount of compression compensation ΔS2 of the steel girder must also be reserved in advance. The temperature of the steel truss girder during hoisting will also cause a change in the mileage direction relative to the design temperature. Therefore, the elongation ΔS3 due to temperature change during hoisting also needs to be reserved in advance. The hoisted girder segment will sway to a certain extent during the hoisting process. In order to avoid the impact of the hoisted girder segment on the already erected girder segment, a certain operating distance ΔS4 needs to be reserved, which can be taken as 5cm to 10cm.

[0078] In another technical solution, in step S6, after adjusting the storage section steel truss beam 3 to the preset installation position, the storage section steel truss beam 3 and the closure section steel truss beam 2 are connected to complete the side span closure construction.

[0079] In this technical solution, after the posture of both ends of the closure section is adjusted and positioned, at a suitable time when the temperature is stable, the longitudinal movement of the storage section steel truss 3 to the first distance S is selected. Then, lateral tensioning is performed to connect the storage section steel truss 3 and the closure section steel truss 2. First, the lower chord 8 is closed. After driving in 50% of the drift pins and installing 30% of the high bolts, the upper chord 10 is closed by raising and lowering the storage section steel truss 3 using a lifting beam, normal tensioning, or an adaptive splicing plate. 50% of the drift pins are driven in and 30% of the high bolts are installed in time. After the upper and lower chords 8 are closed, the diagonal web members 9 are connected. Finally, the upper and lower bridge decks are welded to achieve the side span closure. After the side span is closed, the storage section steel truss 3 is laterally pushed by the lateral jacks at the side pier 5 so that the axis of the storage section steel truss 3 returns to the design theoretical position. Then, lateral locking constraints are applied, and the closure is completed.

[0080] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A construction control method for the side span closure of an asymmetric load steel truss cable-stayed bridge, characterized in that the closure segment steel truss is used to connect the existing steel truss segment at the side span with the cantilever steel truss segment at the middle span for closure, wherein... The construction control method for the side span closure includes the following steps: S1. Hoist the steel truss beam section to the top of the side pier and install it on the side pier; S2. Tension the stay cables of the cantilever steel truss section to the target cable force, and adjust the upstream / downstream elevation of the cantilever steel truss section to the same horizontal level. S3. Hoisting and connecting the closure section steel truss beam with the cantilever section steel truss beam; S4. Adjust the first elevation and first vertical rotation angle of the connection end between the closure section steel truss and the storage section steel truss until they reach the design elevation and design vertical rotation angle; obtain the first lateral bending amount and first lateral rotation angle of the connection end between the closure section steel truss and the storage section steel truss. S5. Adjust the second elevation, second vertical rotation angle, second lateral deflection, and second lateral rotation angle at the joint end of the steel truss girder of the storage section and the steel truss girder of the closure section, so that they are the same as the first elevation, first vertical rotation angle, first lateral deflection, and first lateral rotation angle, respectively. S6. Connect the steel truss girder of the storage section and the steel truss girder of the closure section, and the closure is completed.

2. The construction control method for the side span closure of an asymmetric load steel truss cable-stayed bridge as described in claim 1, characterized in that, In step S1, the initial installation position of the steel truss beam of the storage section on the side pier is a first distance pre-offset from its preset installation position to the side span.

3. The construction control method for the side span closure of an asymmetric load steel truss cable-stayed bridge as described in claim 2, characterized in that, The first distance S satisfies the following relationship: S≥ΔS1+ΔS2+ΔS3+ΔS4; In the formula: ΔS1 is the intersection distance of the diagonal web members of adjacent steel truss segments; ΔS2 is the remaining amount of compression compensation for the steel truss; ΔS3 is the elongation of the steel truss segment due to temperature change; ΔS4 is the operating distance.

4. The construction control method for the side span closure of an asymmetric load steel truss cable-stayed bridge as described in claim 1, characterized in that, In step S2, adjusting the upstream and downstream elevations of the cantilever steel truss section to be at the same horizontal level is based on the upstream / downstream elevation. The downstream / upstream elevation of the cantilever steel truss section is adjusted by adjusting the cable lengths of the downstream / upstream side stay cables. The specific adjustment process is as follows: S21. Calculate the upstream and downstream weight deviations of multiple steel truss segments located in the cable-free zone; take the sum of the multiple weight deviations as the upstream and downstream weight deviation ΔG of the cantilever steel truss segment. i ; S22, Based on the upstream and downstream weight deviation ΔG of the cantilever steel truss section i The difference ΔTi between the upstream and downstream cable forces of the cable to be adjusted is calculated using the following formula: S23. Obtain the cumulative elevation difference Δh between the upstream and downstream sections of the cantilever steel truss. i ; S24. Based on the difference ΔTi between the upstream and downstream cable forces of the stay cable and the cumulative elevation difference Δh between the upstream and downstream sections of the cantilever steel truss girder. i The stress-free cable lengths of the upstream / downstream stay cables relative to the stress-free cable lengths of the downstream / upstream stay cables are calculated using the following formula: Where: xi—the difference between the longitudinal coordinate of the anchor point at the end of the cable-stayed tower and the longitudinal coordinate of the anchor point at the end of the beam; yi — The difference between the x-coordinate of the anchor point at the end of the cable-stayed tower and the x-coordinate of the anchor point at the end of the beam, to be adjusted; zi — The difference between the vertical coordinates of the anchor point at the cable tower end and the vertical coordinates of the anchor point at the beam end, to be adjusted; E—the elastic modulus of the cable; A—Effect cross-sectional area of ​​the cable-stayed cable; q—Severity of the cable-stayed line; S1i—is the unstressed cable length of the downstream / upstream stay cable; S2i—is the stress-free cable length of the stay cable to be adjusted on the upstream / downstream side.

5. The construction control method for the side span closure of an asymmetric load steel truss cable-stayed bridge as described in claim 1, characterized in that, In step S4, jacks are installed at the top of the auxiliary pier located below the cantilever steel truss section, and the first elevation and the first vertical rotation angle are adjusted to the design elevation and the design vertical rotation angle by means of the jacks.

6. The construction control method for the side span closure of an asymmetric load steel truss cable-stayed bridge as described in claim 2, characterized in that, In step S6, after adjusting the storage section steel truss to the preset installation position, the storage section steel truss and the closure section steel truss are connected to complete the side span closure construction.

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