A method for closing a midspan of a steel structure cable-stayed bridge

Abstract

This invention discloses a method for mid-span closure of a steel cable-stayed bridge in the field of bridge construction, including: based on the design length L 设 Operating space L 操 and the length l of each steel beam segment 无应力 Change l 温度 and compression amount l 压缩 Calculate the pre-adjustment value Δ of steel beam segment 0#. 调整 Based on the centerline of the main tower and the pre-adjustment value Δ 调整 Adjust the installation position of steel beam segment 0; construct other steel beam segments on both sides of steel beam segment 0, controlling the unbalanced force of the horizontal component of the tension cable on each steel beam segment towards the mid-span and less than the sum of the frictional resistance on each steel beam segment, forming a closure joint between the two main towers; hoist the closure segment steel beam to the closure joint, install traction and limiting devices at the closure joint, and use the traction and limiting devices to perform the closure operation; weld the steel beams on both sides of the closure joint to the closure segment steel beam; this is to solve the problem of difficult mid-span closure operation of cable-stayed bridges caused by the complex influence of temperature and tensioning equipment.

Description

Technical Field

[0001] This invention belongs to the field of bridge construction technology, specifically relating to a method for mid-span closure of a steel cable-stayed bridge. Background Technology

[0002] Long-span cable-stayed bridges typically employ steel main beams, generally constructed using cantilever construction, with closure occurring midway through the middle span. Mid-span closure is the final and most crucial step in the main bridge structure construction, directly impacting the final bridge configuration. Furthermore, during mid-span closure, the main beam reaches its maximum cantilever, making it highly susceptible to external loads and environmental factors that significantly influence the structural alignment and internal forces. Therefore, a rational closure plan is essential for rapid and high-precision closure, forming a unified structure and enhancing safety.

[0003] Currently, the following closure methods are commonly used for the mid-span closure of long-span steel cable-stayed bridges: (1) Temperature closure: The length of the closure segment is determined by continuously observing the closure gap at the construction site, and the beam is cut on site. This method relies on the structural temperature change to adjust the closure gap, which has a certain degree of uncertainty. When the temperature prediction deviation is too large, it is easy to cause closure failure; (2) Incremental closure: The temporary constraint of the tower and beam is released in advance during closure, and jacks are set at the junction of the tower and beam. The closure gap is manually controlled for the installation of the closure segment. This method requires the setting of jacks during closure, and there are many procedures. When the incremental thrust is large, the bearing capacity of the relevant components needs to be considered. Summary of the Invention

[0004] The purpose of this invention is to provide a method for mid-span closure of a steel cable-stayed bridge, so as to solve the problem of difficult operation of mid-span closure of cable-stayed bridges due to the influence of temperature and complex tensioning equipment.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for mid-span closure of a steel cable-stayed bridge includes:

[0007] Calculate the temperature of each steel beam segment of the cable-stayed bridge at a set temperature T. s And the length l under stress-free conditions 无应力 The steel beams of the cable-stayed bridge include the steel beams from section 0# to section N#, as well as the steel beams of the closure section;

[0008] The actual time for the closure of the mid-span of the cable-stayed bridge was determined based on the construction schedule, and the ambient temperature T at the time of the mid-span closure was obtained using weather forecasting equipment. h ; and length l 无应力 Comparison calculations at ambient temperature T h The change in thermal expansion and contraction of each section of the steel beam l 温度 ;

[0009] Initially, the centerline of steel beam segment 0 of the cable-stayed bridge is aligned with the centerline of the main tower. The compression amount l of each steel beam segment under the action of the stay cables is calculated. 压缩 ; Obtain the design length L from the centerline of steel beam segment 0 to the closure point. 设 Operational space L for hoisting and closure 操 ;

[0010] Based on the design length L 设 Operating space L 操 and the length l of each steel beam segment 无应力 Change l 温度 and compression amount l 压缩 Calculate the pre-adjustment value Δ of steel beam segment 0#. 调整 ;

[0011] Based on the centerline of the main tower and the pre-adjustment value Δ 调整 Adjust the installation position of steel beam segment 0; construct other steel beam segments along both sides of steel beam segment 0, forming a closure joint between the two main towers; designate the steel beams on both sides of the closure joint as steel beam A and steel beam B respectively;

[0012] Adjust the elevation and rotation angle of steel beams A and B; hoist the closure section steel beam to the closure joint, and weld steel beam A to the closure section steel beam and steel beam B to the closure section steel beam to complete the closure.

[0013] Preferably, based on the design length L 设 Operating space L 操 and the length l of each steel beam segment 无应力 Change l 温度 and compression amount l 压缩 Calculate the pre-adjustment value Δ of steel beam segment 0#. 调整 The methods include:

[0014] Based on the length l of each steel beam segment 无应力 Calculate the total length L from the centerline of the main tower to the closure point under stress-free conditions. 无应力 ;

[0015] Based on the changes in each section of the steel beam l 温度 Calculate at ambient temperature T h The total change L of thermal expansion and contraction of the steel beams in each section from the centerline of the main tower to the closure point 温度 ;

[0016] According to the compression amount l of each steel beam segment 压缩 Calculate the total compression L of the steel beams from the centerline of the main tower to the closure point under the action of the stay cables. 压缩 ;

[0017] Calculate the pre-adjustment value Δ of steel beam segment 0#. 调整 The formula is: Δ 调整 =L无应力 -L 设 +L 温度 -L 压缩 +L 操 .

[0018] Preferably, the method for welding steel beam B to the closure segment steel beam includes:

[0019] A traction device and a limiting device are installed between steel beam B and the closure section steel beam. The limiting device is used to restrict the width of the weld between steel beam B and the closure section steel beam. A small traction device is used to assist in adjusting the elevation, rotation angle, axis, etc. of steel beam B and the closure section steel beam until the width of the weld between steel beam B and the closure section steel beam meets the welding requirements. Steel beam B and the closure section steel beam are then welded together to complete the closure.

[0020] Preferably, the method for installing the traction device between steel beam B and the closure section steel beam includes:

[0021] A first anchor block and a jack are installed on steel beam B. The first anchor block provides a force-bearing point for the jack. A second anchor block is installed on the closure section of the steel beam. One end of the tie rod is fixed to the second anchor block, and the other end of the tie rod is connected to the jack. The jack drives the tie rod to move.

[0022] Preferably, the traction device is removed after the weld width between steel beam B and the closure section steel beam meets the welding requirements.

[0023] Preferably, the limiting device includes a top plate and a connecting plate; the connecting plate is vertically connected to the middle of the top plate to form a T-shaped limiting device; the width of the top plate is greater than the weld width between steel beam B and the closure section steel beam.

[0024] Preferably, the method for installing the limiting device between steel beam B and the closure section steel beam includes: placing one side of the top plate on the steel beam B and the other side of the top plate on the closure section steel beam; and placing the connecting plate in the weld between the steel beam B and the closure section steel beam.

[0025] Preferably, it also includes: during the construction of other steel beams along both sides of the 0# steel beam, controlling the unbalanced force of the horizontal component of the tension cable on each steel beam to be directed towards the mid-span and less than the sum of the frictional resistance on each steel beam.

[0026] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0027] This invention is based on the design length L 设 Operating space L 操 and the length l of each steel beam segment 无应力 Change l 温度 and compression amount l 压缩Calculate the pre-adjustment value Δ of steel beam segment 0#. 调整 Based on the centerline of the main tower and the pre-adjustment value Δ 调整 The installation position of the No. 0 segment steel beam was adjusted; the problem of difficult mid-span closure operation of cable-stayed bridge due to temperature and complex tensioning equipment was avoided. The present invention does not require the installation of a jacking device at the main tower. The closure operation can be completed by setting a small anti-pull device at the closure joint, which ensures the efficiency and quality of cable-stayed bridge closure. Attached Figure Description

[0028] Figure 1 This is a front view of the steel cable-stayed bridge with the center line of the 0# segment steel beam and the main tower aligned, as provided by this invention.

[0029] Figure 2 This invention provides the structure of the 0# segment steel beam and the main tower;

[0030] Figure 3 This is a diagram showing the positional relationship between the closure section steel beam, steel beam A, and steel beam B provided by the present invention.

[0031] Figure 4 This is a structural diagram of the traction device provided by the present invention;

[0032] Figure 5 This is a structural diagram of the limiting device provided by the present invention.

[0033] In the diagram: 1 is the main tower, 2 is the steel beam, 21 is the 0# segment steel beam, 2A is steel beam A, 2B is steel beam B, 3 is the closure segment steel beam, 4 is the traction device, 41 is the first anchor block, 42 ​​is the second anchor block, 43 is the jack, 44 is the tie rod, 5 is the limiting device, 51 is the top plate, and 52 is the connecting plate. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0035] It should be noted that in the description of this invention, the terms "front," "rear," "left," "right," "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "front," "rear," "left," "right," "upper," and "lower" used in the description of this invention refer to the directions shown in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0036] like Figures 1 to 5 As shown, a method for mid-span closure of a steel cable-stayed bridge includes:

[0037] Calculate the temperature of each steel beam segment 2 of the cable-stayed bridge at a set temperature T. s And the length l under stress-free conditions 无应力 The steel beams 2 of the cable-stayed bridge include steel beams from section 0# to section N# and the steel beams 3 of the closure section;

[0038] The actual time for the closure of the mid-span of the cable-stayed bridge was determined based on the construction schedule, and the ambient temperature T at the time of the mid-span closure was obtained using weather forecasting equipment. h ; and length l 无应力 Comparison calculations at ambient temperature T h The change in thermal expansion and contraction of each section of the steel beam 2 温度 ;

[0039] Initially, the centerline of steel beam segment 21 (0#) of the cable-stayed bridge is aligned with the centerline of the main tower 1. The compression amount l of each steel beam segment 2 under the action of the stay cables is calculated. 压缩 ; Obtain the design length L from the centerline 21 of steel beam segment 0 to the closure point. 设 Operational space L for hoisting and closure 操 ;

[0040] Based on the design length L 设 Operating space L 操 and the length l of each steel beam segment 无应力 Change l 温度 and compression amount l 压缩 Calculate the pre-adjustment value Δ of steel beam segment 0#. 调整 The specific process is as follows:

[0041] Based on the length l of each steel beam segment 2 无应力 Calculate the total length L from the centerline of main tower 1 to the closure point under stress-free conditions. 无应力 ;

[0042] Based on the change in each section of steel beam 2 l 温度 Calculate at ambient temperature T h The total change L of thermal expansion and contraction of the steel beams in each section from the centerline of the main tower 1 to the closure point 温度 ;

[0043] According to the compression amount l of each section of steel beam 2 压缩 Calculate the total compression L of the steel beams from the centerline of main tower 1 to the closure point under the action of the stay cables. 压缩 ;

[0044] Calculate the pre-adjustment value Δ of steel beam segment 0#. 调整 The formula is: Δ 调整 =L 无应力 -L 设 +L 温度 -L 压缩 +L 操 .

[0045] like Figure 2 As shown, based on the centerline of main tower 1, according to the pre-adjustment value Δ 调整 The installation position of steel beam 21 in segment 0 was adjusted to avoid the difficulties in the mid-span closure operation of the cable-stayed bridge caused by temperature and complex tensioning equipment, thus ensuring the efficiency and quality of the cable-stayed bridge closure. Other steel beams 2 were erected on both sides of steel beam 0, forming a closure joint between the two main towers 1. During the erection of other steel beams on both sides of steel beam 0, the unbalanced force of the horizontal component of the cable force on each steel beam 2 was controlled to be less than the sum of the frictional resistance on each steel beam 2 in the mid-span direction, thus preventing the steel beams from sliding significantly on their own after the temporary constraints of the towers and beams were removed, and ensuring the miniaturization of the tensioning equipment at the closure joint. The steel beams 2 on both sides of the closure joint are designated as steel beam A2A and steel beam B2B, respectively.

[0046] Adjust the elevation and rotation angle of steel beams A2A and B2B; such as Figure 3 As shown, the closure section steel beam is hoisted to the closure joint, and steel beam A2A is directly welded to the closure section steel beam 3;

[0047] like Figure 4 As shown, a traction device 4 is installed between steel beam B2B and the closure section steel beam 3. The traction device 4 includes a first anchor block 41, a second anchor block 42, a jack 43, and a tie rod 44. The specific method for installing the traction device 4 is as follows:

[0048] A first anchor block 41 and a jack 43 are installed on steel beam B2B. The first anchor block 41 provides a force-bearing point for the jack 43. A second anchor block 42 is installed on the closure section steel beam 3. One end of the tie rod 44 is fixed to the second anchor block 42, and the other end of the tie rod 44 is connected to the jack 43. The jack 43 drives the tie rod 44 to move.

[0049] like Figure 5 As shown, a limiting device 5 is installed between steel beam B2B and the closure section steel beam 3; the limiting device 5 restricts the width of the weld between steel beam B2B and the closure section steel beam 3 to ensure a smooth closure process; the limiting device 5 includes a top plate 51 and a connecting plate 52; the connecting plate 52 is vertically connected to the middle of the top plate 51 to form a T-shaped limiting device 5; the width of the top plate 51 is greater than the width of the weld between steel beam B2B and the closure section steel beam 3; one side of the top plate 51 is placed on the steel beam B2B, and the other side of the top plate 51 is placed on the closure section steel beam 3; the connecting plate 52 is placed in the weld between steel beam B2B and the closure section steel beam 3, and the width of the connecting plate 52 is equal to the width of the weld between steel beam B2B and the closure section steel beam 3.

[0050] The elevation, rotation angle, and axis of steel beam B2B and the closure segment steel beam 3 are adjusted by traction device 4 until the weld width between steel beam B2B and the closure segment steel beam 3 meets the welding requirements. After the weld width between steel beam B and the closure segment steel beam meets the welding requirements, traction device 4 is removed. Steel beam B2B and the closure segment steel beam 3 are then welded to complete the closure. The mid-span closure method of this implementation avoids the need to push the steel beam during closure, thus reducing the closure risk.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for mid-span closure of a steel cable-stayed bridge, characterized in that, include Calculate the temperature of each steel beam segment of the cable-stayed bridge at a set temperature T. s And the length l under stress-free conditions 无应力 The steel beams of the cable-stayed bridge include the steel beams from section 0# to section N#, as well as the steel beams of the closure section; The actual time for the closure of the mid-span of the cable-stayed bridge was determined based on the construction schedule, and the ambient temperature T at the time of the mid-span closure was obtained using weather forecasting equipment. h ; and length l 无应力 Comparison calculations at ambient temperature T h The change in thermal expansion and contraction of each section of the steel beam l 温度 ; Initially, the centerline of steel beam segment 0 of the cable-stayed bridge is aligned with the centerline of the main tower. The compression amount l of each steel beam segment under the action of the stay cables is calculated. 压缩 ; Obtain the design length L from the centerline of steel beam segment 0 to the closure point. 设 Operational space L for hoisting and closure 操 ; Based on the design length L 设 Operating space L 操 and the length l of each steel beam segment 无应力 Change l 温度 and compression amount l 压缩 Calculate the pre-adjustment value Δ of steel beam segment 0#. 调整 ; Based on the centerline of the main tower and the pre-adjustment value Δ 调整 Adjust the installation position of steel beam segment 0; construct other steel beam segments along both sides of steel beam segment 0, forming a closure joint between the two main towers; designate the steel beams on both sides of the closure joint as steel beam A and steel beam B respectively; Adjust the elevation and rotation angle of steel beams A and B; hoist the closure section steel beam to the closure joint, and weld steel beam A to the closure section steel beam and steel beam B to the closure section steel beam to complete the closure.

2. The method for mid-span closure of a steel cable-stayed bridge according to claim 1, characterized in that, Based on the design length L 设 Operating space L 操 and the length l of each steel beam segment 无应力 Change l 温度 and compression amount l 压缩 Calculate the pre-adjustment value Δ of steel beam segment 0#. 调整 The methods include: Based on the length l of each steel beam segment 无应力 Calculate the total length L from the centerline of the main tower to the closure point under stress-free conditions. 无应力 ; Based on the changes in each section of the steel beam l 温度 Calculate at ambient temperature T h The total change L of thermal expansion and contraction of the steel beams in each section from the centerline of the main tower to the closure point 温度 ; According to the compression amount l of each steel beam segment 压缩 Calculate the total compression L of the steel beams from the centerline of the main tower to the closure point under the action of the stay cables. 压缩 ; Calculate the pre-adjustment value Δ of steel beam segment 0#. 调整 The formula is: Δ 调整 =L 无应力 -L 设 +L 温度 -L 压缩 +L 操 .

3. The method for mid-span closure of a steel cable-stayed bridge according to claim 1, characterized in that, The methods for welding steel beam B to the closure section steel beam include: A traction device and a limiting device are installed between steel beam B and the closure section steel beam. The limiting device is used to restrict the width of the weld between steel beam B and the closure section steel beam. A small traction device is used to assist in adjusting the elevation, rotation angle, and axis of steel beam B and the closure section steel beam until the width of the weld between steel beam B and the closure section steel beam meets the welding requirements. Steel beam B and the closure section steel beam are then welded together to complete the closure.

4. The method for mid-span closure of a steel cable-stayed bridge according to claim 3, characterized in that, The method for installing a traction device between steel beam B and the closure section steel beam includes: A first anchor block and a jack are installed on steel beam B. The first anchor block provides a force-bearing point for the jack. A second anchor block is installed on the closure section of the steel beam. One end of the tie rod is fixed to the second anchor block, and the other end of the tie rod is connected to the jack. The jack drives the tie rod to move.

5. The method for mid-span closure of a steel cable-stayed bridge according to claim 3, characterized in that, The limiting device includes a top plate and a connecting plate; the connecting plate is vertically connected to the middle of the top plate to form a T-shaped limiting device; the width of the top plate is greater than the weld width between steel beam B and the closure section steel beam.

6. The method for mid-span closure of a steel cable-stayed bridge according to claim 5, characterized in that, The method for installing a limiting device between steel beam B and the closure section steel beam includes: placing one side of the top plate on the steel beam B and the other side of the top plate on the closure section steel beam; and placing a connecting plate in the weld between the steel beam B and the closure section steel beam.

7. The method for mid-span closure of a steel cable-stayed bridge according to claim 1, characterized in that, Also includes: During the construction of other steel beams along both sides of steel beam segment 0, the unbalanced force of the horizontal component of the tension cable on each steel beam is controlled to be directed towards the mid-span and less than the sum of the frictional resistance on each steel beam segment.

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