A method for installing a main truss of a steel truss bridge

Abstract

The present application relates to a kind of steel truss installation construction technology field, in particular to a kind of main truss installation method of steel truss bridge, comprising the following installation steps: step S1: installation vertical web member, step S2: installation upper chord, step S3: the upper chord elevation retest, adjustment, step S4: installation lower chord, step S4: installation diagonal web member, step S6: the lower chord elevation retest, adjustment, step S7: repeat step S1-S6, complete the installation of main truss.It is convenient to install upper chord again through first support device and / or second support device by being provided with first support device and second support device at the junction of vertical web member both ends, by being provided with third support device between diagonal web member and lower chord, first lifting device between diagonal web member and upper chord and first lifting device between upper chord and lower chord, it is convenient to adjust third support device, first lifting device and second lifting device after installing lower chord.

Description

Technical Field

[0001] This invention relates to the field of steel truss installation and construction technology, and particularly to a method for installing the main truss of a steel truss bridge. Background Technology

[0002] Steel truss bridges are mainly composed of truss members. The main truss is generally a triangular truss or an N-shaped truss, and is mostly used in double-deck bridges. The web members and node plates are usually connected by butt joints or insert joints with splice plates. Depending on the bridge width, a structure of two or more main trusses is selected. Long-span steel truss cable-stayed bridges spanning rivers are mostly erected using the cantilever method. During the cantilever construction, no temporary supports are required, and the members are sequentially suspended and assembled onto another pier (abutment).

[0003] Pre-assembly of the main truss of steel trusses is generally carried out on a special jig, with each member in a stress-free state. The main trusses are mostly pre-assembled in a "flat-hanging" manner, and the pre-assembly alignment of the relative nodes between the two main trusses differs from that of the cantilever. In the actual on-site installation process, due to manufacturing errors during production and installation errors during installation, the members of the main truss still need to be re-measured and readjusted after installation. The traditional installation method is to weld the members of the main truss after positioning and then install bolts. When readjustment is required, the original welded joints must be cut open and readjusted. This is not only time-consuming and labor-intensive, but also extremely inefficient when multiple adjustments are required. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by providing a method for installing the main truss of a steel truss bridge, thereby facilitating multiple adjustments to the members of the main truss during installation, reducing the workload of the main truss installation, and improving installation efficiency.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A method for installing the main truss of a steel truss bridge, based on existing lower chords and existing upper chords, wherein the front end of the existing lower chord extends beyond the existing upper chord, the method comprising the following steps:

[0007] Step S1: Install vertical web member: Install the vertical web member at the front end of the existing lower chord, and set a first support device at the connection between the vertical web member and the existing lower chord. The first support device is used to adjust the vertical relative position between the vertical web member and the existing lower chord.

[0008] Step S2: Install the upper chord: The rear end of the upper chord is connected to the existing upper chord, the front part of the upper chord is connected to the vertical web member, and a second support device is set at the connection between the vertical web member and the upper chord member. The second support device is used to adjust the vertical relative position between the vertical web member and the upper chord member.

[0009] Step S3: Re-measurement and adjustment of the upper chord elevation: Measure whether the upper chord elevation reaches the theoretical elevation range. If not, adjust the height of the first support device and / or the second support device to bring the upper chord elevation to the theoretical elevation range, and then temporarily lock the upper chord.

[0010] Step S4: Install the lower chord: Install the lower chord at the front end of the existing lower chord;

[0011] Step S5: Install the diagonal brace: The upper part of the diagonal brace is connected to the upper chord, the lower part of the diagonal brace is connected to the front part of the lower chord, a first lifting device is provided between the diagonal brace and the upper chord, a second lifting device is provided between the lower chord and the upper chord, and a third support device is provided between the diagonal brace and the lower chord. The third support device is used to adjust the angle and / or vertical relative position between the diagonal brace and the lower chord.

[0012] Step S6: Re-measurement and adjustment of the lower chord elevation: Measure whether the elevation of the lower chord reaches the theoretical elevation range. If it does not reach the theoretical elevation range, adjust the third support device, the first lifting device and the second lifting device to make the lower chord elevation reach the theoretical elevation range, and then temporarily lock the lower chord.

[0013] Step S7: Repeat steps S1-S6 to complete the installation of the main truss.

[0014] The present invention discloses a method for installing the main truss of a steel truss bridge. During the installation of the upper chord, a first support device and a second support device are installed at the connection points of the vertical web members. This facilitates readjustment of the upper chord after installation using the first and / or second support devices, thus avoiding the situation where the upper chord is difficult to adjust after installation. Simultaneously, during the installation of the lower chord, a third support device is installed between the diagonal web members and the lower chord, a first lifting device is installed between the diagonal web members and the upper chord, and a first lifting device is installed between the upper and lower chords. This facilitates adjustment of the lower chord after installation using the third support device, the first lifting device, and the second lifting device, thus avoiding the situation where the lower chord is difficult to adjust after installation. Furthermore, the method for installing the main truss of a steel truss bridge, by setting up support devices and lifting devices, makes the re-measurement and adjustment of the main truss segments after installation more convenient, simple to operate, and highly efficient.

[0015] Preferably, the adjustment of the vertical web member and the existing lower chord member in step S1 specifically includes the following steps:

[0016] S11: The vertical web member is connected to the existing lower chord member by a first punch, and there is a first gap between the first punch and the punch hole of the vertical web member;

[0017] S12: The gap between the vertical web member and the existing lower chord member is filled by the first support device;

[0018] S13: Adjust the height of the support pad of the first support device appropriately according to the adjustment direction of the vertical web rod. If it needs to be lowered, make the upper part of the punch hole of the vertical web rod contact the first punch and move the first gap to the bottom of the first punch. If it needs to be raised, make the lower part of the punch hole of the vertical web rod contact the first punch and move the first gap to the top of the first punch.

[0019] Preferably, the adjustment of the vertical web member and the upper chord member in step S2 specifically includes the following steps:

[0020] S21: The vertical web member is connected to the upper chord member by a second punch, and there is a second gap between the second punch and the punch hole of the upper chord member;

[0021] S22: The gap between the vertical web member and the upper chord member is filled by the second support device;

[0022] S23: Adjust the height of the support pad of the second support device appropriately according to the adjustment direction of the upper chord. If it needs to be lowered, make the upper part of the upper chord punch hole contact the second punch and move the second gap to the lower part of the second punch. If it needs to be raised, make the lower part of the upper chord punch hole contact the second punch and move the second gap to the upper part of the second punch.

[0023] Preferably, the adjustment of the diagonal web member and the lower chord member in step S5 specifically includes the following steps:

[0024] S51: The diagonal web member is connected to the lower chord member by a third punch, and there is a third gap between the third punch and the punch hole of the diagonal web member;

[0025] S52: The gap between the inclined web member and the lower chord member is filled by a three-support device;

[0026] S53: Determine the lengthening or shortening of the diagonal brace based on the adjustment direction of the lower chord, and appropriately adjust the support height of the third support device. If the lower chord needs to be lowered, lengthen the diagonal brace, bring the upper part of the diagonal brace punch hole into contact with the third punch, and transfer the third gap to the lower part of the third punch. If the lower chord needs to be raised, shorten the diagonal brace, bring the lower part of the diagonal brace punch hole into contact with the third punch, and transfer the third gap to the upper part of the third punch.

[0027] Preferably, step S3 further includes: installing a cross brace located below the upper chord, the cross brace being used to connect the two vertical web members along the cross-sectional direction of the steel truss bridge.

[0028] Preferably, step S7 further includes: installing the upper bridge panel and the lower bridge panel.

[0029] Preferably, the first support device, the second support device, and the third support device all include wedges or jacks.

[0030] Preferably, the first lifting device includes a chain hoist and a sling.

[0031] Preferably, the second lifting device consists of a tensioning end, a pull rod, and a fixed end. The tensioning end is connected to the end of the upper chord, the fixed end is connected to the end of the lower chord, and the pull rod is used to connect the tensioning end and the fixed end.

[0032] Preferably, it also includes a method for adjusting the height difference between the members of the main truss:

[0033] Step A: Determine the diameter of the punch used for adjustment;

[0034] Step B: Calculate the theoretical height difference adjustment amount for the chord segments based on the selected punch diameter;

[0035] Step C: Analysis of the adjustable length of the web member;

[0036] Step D: Set up auxiliary adjustment devices.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] 1. The present invention discloses a method for installing the main truss of a steel truss bridge. During the installation of the upper chord, a first support device and a second support device are set at the connection points of the vertical web members. This facilitates readjustment of the upper chord after installation using the first and / or second support devices, thus avoiding the situation where the upper chord is difficult to adjust after installation. Simultaneously, during the installation of the lower chord, a third support device is set between the diagonal web members and the lower chord, a first lifting device is set between the diagonal web members and the upper chord, and a first lifting device is set between the upper and lower chords. This facilitates adjustment of the lower chord after installation using the third support device, the first lifting device, and the second lifting device, thus avoiding the situation where the lower chord is difficult to adjust after installation. Furthermore, the method for installing the main truss of a steel truss bridge, by setting up support devices and lifting devices, makes the re-measurement and adjustment of each member of the main truss after installation more convenient, simple to operate, and highly efficient in adjustment. Attached image description:

[0039] Figure 1 This is a schematic diagram of the installation process of the present invention.

[0040] Figure 2 This is a schematic diagram of the main truss of the steel truss bridge of the present invention.

[0041] Figure 3 This is a cross-sectional schematic diagram of the main truss of the steel truss bridge of the present invention.

[0042] Figure 4 This is a schematic diagram of the installation of the vertical web members of the main truss of the steel truss bridge according to the present invention.

[0043] Figure 5 yes Figure 4 A schematic diagram of direction A.

[0044] Figure 6 yes Figure 5 A schematic diagram of direction B.

[0045] Figure 7 This is a schematic diagram of the installation of the upper chord of the main truss of the steel truss bridge according to the present invention.

[0046] Figure 8 yes Figure 7 A schematic diagram of direction C.

[0047] Figure 9 yes Figure 8 A schematic diagram of direction D.

[0048] Figure 10 This is a schematic diagram of the horizontal connection installation of the main truss of the present invention.

[0049] Figure 11 This is a schematic diagram of the installation of the lower chord of the main truss of the present invention.

[0050] Figure 12 This is a schematic diagram of the installation of the main truss diagonal web members of the present invention.

[0051] Figure 13 This is a schematic diagram of the installation of the support device and lifting device of the main truss of the present invention.

[0052] Figure 14 yes Figure 13 A schematic diagram of direction E.

[0053] Figure 15 This is a schematic diagram of the main truss installation section control points of the present invention.

[0054] Figure 16 This is a simplified schematic diagram of the main truss installation section control points of the present invention.

[0055] Figure 17 This is a simplified diagram of the arrangement of punch holes in the main truss chord connection nodes of the present invention.

[0056] Figure 18 This is a schematic diagram of the punch holes and punch arrangement of the main truss chord connection nodes of the present invention.

[0057] Figure 19 This is a schematic diagram of the rotation angle of the main truss chord connection node of the present invention. Figure 1 .

[0058] Figure 20 This is a schematic diagram of the rotation angle of the main truss chord connection node of the present invention. Figure 2 .

[0059] Figure 21 This is a schematic diagram of the rotation coordinate change at the cantilever end of the main truss chord of the present invention.

[0060] Figure 22 This is a schematic diagram (length adjustment) of the punch hole misalignment adjustment at the connection point between the main truss web members and the chord members of the present invention.

[0061] Figure 23 This is a schematic diagram of the adjustment (shortening) of the punch hole misalignment at the connection point between the main truss web member and the chord member of the present invention.

[0062] Figure 24 This is a schematic diagram showing the change of the vertical rotation control point of the main truss chord in this invention.

[0063] Figure 25 This is a schematic diagram of the force on the punches and punch holes between the main truss chords of the present invention.

[0064] The markings in the diagram are: 1-Upper chord, 2-Lower chord, 3-Vertical web member, 4-Diagonal web member, 5-Horizontal bracing, 6-First support device, 7-Second support device, 8-Third support device, 9-First lifting device, 10-Second lifting device, 11-Stay cable, 13-Splice plate, 131-Splice plate bolt hole, 14-Chord to be installed, 141-Chord to be installed punch hole, 15-Installed chord, 151-Installed chord punch hole, 16-Main pier, 17-Existing lower chord, 18-Existing upper chord, 19-Upper bridge deck, 20-Lower bridge deck, 121-Small punch, 122-Large punch. Detailed Implementation

[0065] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0066] Example 1

[0067] like Figures 1-3 As shown, a method for installing the main truss of a steel truss bridge, based on an existing lower chord 17 and an existing upper chord 18, wherein the front end of the existing lower chord 17 extends beyond the existing upper chord 18, the installation method includes the following steps:

[0068] Step S1: Install vertical web member 3: The lower chord 17 already has a vertical web member 3 installed at its front end, such as... Figures 4-6 As shown, when installing the vertical web member 3, a bridge erecting machine on the main truss segment that has already been installed is used for hoisting. During the hoisting process, the vertical web member 3 must be kept vertical. A first support device 6 is set at the connection between the vertical web member 3 and the existing lower chord member 17. The first support device 6 is used to adjust the vertical relative position between the vertical web member 3 and the existing lower chord member 17.

[0069] Step S2: Install the upper chord 1: as follows Figures 7-9 As shown, the rear end of the upper chord 1 is connected to the existing upper chord 18, the front part of the upper chord 1 is connected to the vertical web member 3, and a second support device 7 is provided at the connection between the vertical web member 3 and the upper chord 1. The second support device 7 is used to adjust the vertical relative position between the vertical web member 3 and the upper chord 1.

[0070] Among them, the upper chord 1 is hoisted by the bridge erecting machine. In order to ensure the stability of the upper chord 1 hoisting process, it is advisable to adopt the multi-point hoisting method to ensure that the upper chord 1 is horizontal during the installation process and does not tilt.

[0071] Step S3: Re-measurement and adjustment of the elevation of the upper chord 1: After the upper chord 1 is installed, use a level to measure whether the elevation of the upper chord 1 reaches the theoretical elevation range of the upper chord. If it does not reach the theoretical elevation range, adjust the height of the first support device 6 and / or the second support device 7 to make the elevation of the upper chord 1 reach the theoretical elevation range of the upper chord. Then, temporarily lock the upper chord 1.

[0072] The theoretical elevation range of the upper chord consists of the theoretical elevation value of the upper chord plus the error range.

[0073] When adjusting the upper chord 1, a bridge erecting machine is used to lift its end appropriately according to the weight of the upper chord 1. Then, the height of the first support device 6 and / or the second support device 7 is adjusted as needed until the adjustment amount meets the theoretical elevation value range. Then, a re-measurement is carried out until there are no errors. The upper chord 1 is temporarily locked. The temporary locking can be achieved by inserting a small number of high-strength bolts into the punch holes.

[0074] Step S4: Install the lower chord 2: as follows Figure 11 As shown, a lower chord 2 is installed at the front end of the existing lower chord 17;

[0075] Step S5: Install diagonal brace 4: as shown Figures 12-13As shown, the upper part of the diagonal web member 4 is connected to the upper chord member 1, the lower part of the diagonal web member 4 is connected to the front part of the lower chord member 2, a first lifting device 9 is provided between the diagonal web member 4 and the upper chord member 1, a second lifting device 10 is provided between the lower chord member 2 and the upper chord member 1, and a third support device 8 is provided between the diagonal web member 4 and the lower chord member 2. The third support device 8 is used to adjust the angle and / or vertical relative position between the diagonal web member 4 and the lower chord member 2.

[0076] Step S6: Re-measurement and adjustment of the elevation of the lower chord 2: After the lower chord 2 is installed, use a level to measure whether the elevation of the lower chord 2 reaches the theoretical elevation range of the lower chord. If it does not reach the theoretical elevation range, adjust the third support device 8, the first lifting device 9 and the second lifting device 10 to make the elevation of the lower chord 2 reach the theoretical elevation range of the lower chord. Then, temporarily lock the lower chord 2.

[0077] The theoretical elevation range of the lower chord consists of the theoretical elevation value of the lower chord plus the error range.

[0078] When adjusting the lower chord 2, a bridge erecting machine is used. The end of the lower chord 2 is lifted appropriately according to its weight. Then, the height of the third support device 8 and the length of the first lifting device 9 and the second lifting device 10 are adjusted as needed until the adjustment meets the theoretical elevation value range. Then, a re-measurement is carried out until there are no errors. The lower chord 2 is temporarily locked. The temporary locking can be achieved by inserting a small number of high-strength bolts into the punch holes.

[0079] Step S7: Repeat steps S1-S6 to complete the installation of the main truss.

[0080] The present invention discloses a method for installing the main truss of a steel truss bridge. During the installation of the upper chord 1, a first support device 6 and a second support device 7 are set at the connection points of the two ends of the vertical web members 3. This facilitates readjustment of the upper chord 1 after installation using the first support device 6 and / or the second support device 7, thus avoiding the situation where the upper chord 1 is inconvenient to adjust after installation. Simultaneously, during the installation of the lower chord 2, a third support device 8 is set between the diagonal web members 4 and the lower chord 2, a first lifting device 9 is set between the diagonal web members 4 and the upper chord 1, and a first lifting device 9 is set between the upper chord 1 and the lower chord 2. This facilitates adjustment of the lower chord 2 after installation using the third support device 8, the first lifting device 9, and the second lifting device 10, thus avoiding the situation where the lower chord 2 is inconvenient to adjust after installation. Furthermore, the method for installing the main truss of a steel truss bridge disclosed in this invention, by setting up support devices and lifting devices, makes the re-measurement and adjustment of the main truss segments after installation more convenient, simple to operate, and highly efficient in adjustment.

[0081] In a preferred manner, the adjustment of the vertical web member 3 and the existing lower chord member 17 in step S1 specifically includes the following steps:

[0082] S11: The vertical web member 3 is connected to the existing lower chord member 17 through the first punch, and there is a first gap between the first punch and the punch hole;

[0083] S12: The gap between the vertical web member 3 and the existing lower chord member 17 is filled by the first support device 6;

[0084] S13: Adjust the support height of the first support device 6 appropriately according to the adjustment direction of the vertical web member 3. During adjustment, the bridge erecting machine does not release the hook, and the upward lifting force of the bridge erecting machine is equal to the weight of the vertical web member 3, so that the vertical web member 3 is in a state of force balance. Since the lower end of the vertical web member 3 is connected to the existing lower chord 17 through the first punch, there is a first gap between the first punch and the punch hole. Adjust the position of the first gap to adjust the vertical relative position of the vertical web member 3 on the existing lower chord 17. If it is necessary to lower the vertical web member 3, that is, adjust it downward, so that the upper part of the punch hole of the vertical web member 3 contacts the first punch, and the first gap is transferred to the lower part of the first punch, so that the vertical web member 3... If the vertical height is reduced, the height of the first support device 6 is adjusted to fill the gap between the vertical web member 3 and the existing lower chord 17, thus fixing the vertical web member 3 and the existing lower chord 17 relative to each other, thereby completing the adjustment of the vertical web member 3. If the vertical web member 3 needs to be raised, i.e., adjusted upwards, the lower part of the punch hole is made to contact the first punch, and the first gap is moved to the upper part of the first punch, so that the vertical height of the vertical web member 3 increases. Then the height of the first support device 6 is adjusted to fill the gap between the vertical web member 3 and the existing lower chord 17, thus fixing the vertical web member 3 and the lower suspension rod 1 of the previous stage relative to each other, thereby completing the relative height adjustment of the vertical web member 3.

[0085] In a preferred embodiment, the adjustment of the vertical web member 3 and the upper chord member 1 in step S2 specifically includes the following steps:

[0086] S21: The vertical web member 3 is connected to the upper chord member 1 through the second punch, and the second punch and the punch hole are the second gap;

[0087] S22: The gap at the connection surface between the vertical web member 4 and the upper chord member 1 is filled by the second support device 7;

[0088] S23: Adjust the support height of the second support device 7 appropriately according to the adjustment direction of the upper chord 1. During adjustment, the bridge erecting machine should not loosen its hook. The upward lifting force of the bridge erecting machine should be equal to the weight of the upper chord 1 itself, so that the upper chord 1 is in a state of force balance. Since the upper chord 1 and the upper end of the vertical web member 3 are connected by the second punch, there is a second gap between the second punch and the punch hole. The vertical relative position between the upper chord 1 and the vertical web member 3 is adjusted by adjusting the position of the second gap. If it is necessary to lower the upper chord 1, that is, when adjusting the end of the upper chord 1 downward, the upper part of the punch hole of the upper chord 1 should contact the second punch, and the second gap should be moved to the lower part of the second punch, so that the end of the upper chord 1... If the height of the head decreases in the vertical direction, the second support device 7 is adjusted to fill the gap between the connecting surfaces of the upper chord 1 and the vertical web member 3, so that the bottom surface of the upper chord 1 is relatively fixed with the vertical web member 3, thereby completing the relative height adjustment of the upper chord 1; if it is necessary to raise the upper chord 1, that is, when the end of the upper chord 1 is adjusted upward, the lower part of the punch hole of the upper chord 1 contacts the second punch, the second gap is transferred to the upper part of the second punch, so that the height of the end of the upper chord 1 in the vertical direction increases, and the second support device 7 is adjusted to fill the gap between the connecting surfaces of the upper chord 1 and the vertical web member 3, so that the bottom surface of the upper chord 1 is relatively fixed with the vertical web member 3, thereby completing the relative height adjustment of the upper chord 1.

[0089] One preferred approach, the adjustment of the diagonal web member 4 and the lower chord member 2 in step S5, specifically includes the following steps:

[0090] S51: The diagonal web member 4 is connected to the lower chord member 2 through the third punch, and there is a third gap between the third punch and the punch hole;

[0091] S52: The gap between the inclined web member 4 and the lower chord member 2 is filled by the third support device 8;

[0092] S53: Determine the lengthening or shortening of the diagonal brace 4 based on the adjustment direction of the lower chord 2. Adjust the support height of the third support device 8 appropriately, and use the bridge erecting machine to appropriately lift the front end of the lower chord 2 to bring it into a state of force balance. This allows for adjustment of the relative position between the lower chord 2 and the diagonal brace 4. Since the front part of the lower chord 2 is connected to the diagonal brace 4 via a third punch, there is a third gap between the third punch and the punch hole. Adjusting the position of the third gap adjusts the length of the diagonal brace 4, thereby adjusting the elevation of the front part of the lower chord 2. If it is necessary to lower the lower chord 2, lengthen the diagonal brace 4, bringing the upper part of the punch hole of the diagonal brace 4 into contact with the third punch, and shifting the third gap to the lower part of the third punch, so that the diagonal brace 4 is aligned with the lower chord 2. The length of the lower chord 2 is increased by adjusting the third support device 8 to fill the gap between the diagonal brace 4 and the lower chord 2, thus fixing the diagonal brace 4 and the lower chord 2 relative to each other and completing the relative height adjustment of the lower chord 2. If the lower chord 2 needs to be raised, the diagonal brace 4 is shortened, and the lower part of the punch hole of the diagonal brace 4 is brought into contact with the third punch. The third gap is moved to the upper part of the third punch, reducing the length of the diagonal brace 4 along its length direction. This causes the end of the lower chord 2 to shift upward. The gap between the diagonal brace 4 and the lower chord 2 is then filled by adjusting the third support device 8, thus fixing the diagonal brace 4 and the lower chord 2 relative to each other and completing the relative height adjustment of the lower chord 2.

[0093] A preferred method, such as Figure 10 As shown, step S3 further includes: installing a cross brace 5 located below the upper chord 1. The cross brace 5 is used to connect two vertical web members 3 along the cross-sectional direction of the steel truss bridge, as shown. Figure 3 .

[0094] In one preferred manner, step S7 further includes: installing the upper bridge panel 19 and the lower bridge panel 20; further, after step S3, as... Figure 10 As shown, an upper bridge panel 19 is installed between the upper chord members 1 to fix the distance between the two upper chord members 1 along the cross-sectional direction of the steel truss bridge; after step S5, as... Figure 13 As shown, a lower bridge panel 20 is installed between the lower chord members 2 to fix the distance between the two lower chord members 2 along the cross-section direction of the steel truss bridge.

[0095] In a preferred embodiment, the first support device 6, the second support device 7, and the third support device 8 all include wedges or jacks. Furthermore, when using wedges as support devices, the height can be adjusted by replacing different wedges or by increasing or decreasing the number of wedges. When using jacks, mechanical jacks and hydraulic jacks are included.

[0096] A preferred method, such as Figure 13As shown, the first lifting device 9 is connected to the end of the upper chord 1 and the upper part of the inclined web 4 at both ends. The first lifting device 9 includes a chain hoist and a sling. The first lifting device 9 is used to balance the weight of the inclined web 4. When the lower chord 2 is adjusted, the first lifting device 9 is first relaxed. After the lower chord 2 is adjusted, the first lifting device 9 is tightened.

[0097] A preferred method, such as Figure 14 As shown, the second lifting device 10 consists of a tensioning end 101, a tie rod 102, and a fixed end 103. The tensioning end 101 is installed at the end of the upper chord 1, the fixed end 103 is installed at the end of the lower chord 2, and the tie rod 102 is installed between the tensioning end 101 and the fixed end 102. The length of the tie rod 102 is adjusted by the tensioning end 101, thereby controlling the tightening and loosening of the second lifting device 10. The second lifting device 10 is used to balance the weight of the lower chord 2. When adjusting the lower chord 2, the second lifting device 10 is first in a relaxed state. After the lower chord 2 is adjusted, the second lifting device 10 is tightened. Furthermore, the tensioning end 101 and the fixed end 102 are reaction supports, and the tie rod 102 is a precision-rolled threaded steel bar with a diameter greater than or equal to 32mm.

[0098] In a preferred embodiment, step S7 further includes: connecting the upper chord 1 to the main pier 16 via the stay cable 11, so that the main truss is less prone to deflection under the tension of the main pier 16.

[0099] A preferred approach also includes a method for adjusting the height difference of the main truss chord members. The principle is to utilize the minute gap between the punch and the punch hole to create a small vertical rotation angle between the upper chord 1 and the lower chord 2 around the connection node. The lengths of the vertical web members 3 and the diagonal web members 4 can be adjusted within the gap range between the punch and the punch hole, allowing the elevation of the cantilever end of the chord member to be adjusted upwards or downwards. This enables the elevation of the cantilever ends of the upper chord 1 and the lower chord 2 to be adjusted within a certain range. The steps are as follows:

[0100] Step A: Determine the diameter of the punch used for adjustment:

[0101] According to the "Technical Specification for Construction of High-Speed ​​Railway Bridges and Culverts J1148-2018", the nominal diameter of the punch used for assembly should be 0.1mm to 0.3mm smaller than the design hole diameter (φA) (the upper limit should be used for cantilever assembly). The punch diameter selected for cantilever assembly of steel trusses is: φM1 = φA - 0.3mm. According to the "Technical Specification for High-Strength Bolt Connection of Steel Structures JGJ82-2011", the minimum punch diameter can be: φM2 = φB - 1.0mm (φB is the nominal diameter of the punch hole).

[0102] Step B: Calculate the theoretical height difference adjustment amount for the chord segments based on the selected punch diameter:

[0103] Based on the pre-camber of the steel truss girder during fabrication, the relative coordinates of the chord members of the cantilever segment to be installed are determined relative to the already installed beam segments. The intersection points of the axes of all truss members in the main truss are the theoretically calculated control coordinates. For example... Figures 15-16 As shown, taking point a0 as the origin, the coordinates of the remaining control points a1, a2, a3, e1, e2, e3, and e4 can be determined based on the theoretical alignment of the steel truss beam manufacturing process.

[0104] Among them, such as Figure 17 As shown, in the steel truss bridge, C is the end of the chord to be installed 14, and D is the end of the chord 15 that has been installed. The connection between the end C of the chord to be installed and the end D of the chord 15 is made by butt joint of splice plate 13. The ends of the chord to be installed 14 and the chord 15 that have been installed are arranged with punch holes at a certain interval.

[0105] like Figure 18 As shown, the end D of the installed chord 15 is fixed. The splicing plate 13 and the end D of the installed chord 15 are connected by a large punch 122 with a diameter of φM1 at the upper right corner and a small punch 121 with a diameter of φM2 at the lower left corner. The maximum gap between the small punch 121 and the punch hole is d = φM2 - φB = 1mm.

[0106] The direction pointing to the installed chord 15 is defined as the right, and the direction pointing to the chord 14 to be installed is defined as the left.

[0107] like Figure 19 As shown, the splicing plate 13 rotates counterclockwise around the large punch 122 in the upper right corner until the punch hole 131 in the lower left corner of the splicing plate contacts the small punch 121. Its rotation radius is the center distance R between the two holes. When the punch hole 131 in the lower left corner of the splicing plate contacts the small punch 121, the punch hole 151 of the installed chord is located above the punch hole 131 in the splicing plate, which is the maximum rotation angle a°=sin-1(d÷R).

[0108] like Figure 20 As shown, when the end C of the chord member 14 to be installed rotates counterclockwise by a° around its upper right corner large punch 122, its lower left corner small punch 121 contacts the two punch hole plates. At this time, the punch hole 151 of the already installed chord member is located above the punch hole 131 of the splicing plate, and the punch hole 141 of the chord member to be installed is located below the punch hole 131 of the splicing plate. At this point: the connecting end C of the chord member to be installed rotates downwards by 2a° = 2sin⁻¹(d÷R) compared to the connecting end D of the already installed chord member.

[0109] Similarly, if the large and small punches are interchanged, they can be rotated upwards by 2a°.

[0110] Step C: Analysis of the adjustable length of the web member:

[0111] like Figure 21As shown, let A be the connection end between the chord 14 to be installed and the chord 15 already installed. Then, the chord can rotate upward or downward around A through the gap between the large punch 122 and the punch hole. The rotation point is A(0,0), and the end of the chord is B(xb,yb). If the chord rotates downward by 2a° to point B'(xb',yb'), we can obtain the following from the geometric relationship:

[0112] ΔX=[sin(a)×L×2]×sin(a); Δy=[sin(a)×L×2]×cos(a)

[0113] From the above formula, the coordinates of B' are: B'(xb-ΔX, yb-Δy)

[0114] Where L is the length of the chord;

[0115] like Figures 22-23 As shown, during the assembly of the steel truss girder, the actual maximum adjustable angle of the upper and lower chords is limited by the adjustable length of the vertical web members 3 and diagonal web members 4 between the upper and lower chords. Therefore, small punch 121 is selected for the first, second, and third punches during installation. Since the use of angled adjustment chords will cause the punch holes in the punch hole plate layers to intersect, the allowable intersect adjustment length ΔL1 of a single vertical web member 3 and diagonal web member 4 through the punch hole plate is:

[0116] -d≤△L1≤+d

[0117] Similarly: the sum of the two ends of a single vertical web member 3 and a diagonal web member 4 can be adjusted by staggering the length △L2 through the punch pin hole plate as follows:

[0118] -2d≤△L2≤+2d

[0119] like Figure 16 and Figure 24 As shown, due to the limitation of the chord angle adjustment and the web member length adjustment by the diameter of the small punch 121, after the main truss members are assembled:

[0120] The upper chord 1 can rotate downwards by a maximum of α (α≤2a), at which point the vertical web member 3: a2'e1=a2e1-2d; conversely, it can rotate upwards by a maximum of α, at which point the vertical web member 3: a2'e1=a2e1+2d.

[0121] When the upper chord 1 rotates downward by α, the lower chord 2 rotates downward by a maximum of β (β≤2a). At this time, the diagonal web member 4 is: a2'e3'=a2e3+2d. Conversely, when the upper chord 1 rotates upward by α, the lower chord 2 rotates upward by a maximum of β. At this time, the diagonal web member 4 is: a2'e3'=a2e3-2d.

[0122] Step D: Set and adjust auxiliary devices:

[0123] During the adjustment of the chord, such as Figure 25 As shown, the gap between the small punch 121 and the punch hole is relatively large. Without auxiliary measures, the two punch hole plates will be misaligned vertically. After being subjected to force, the small punch 121 tilts until the punch surface and the punch hole surface are pressed together. Since the contact area between the punch hole and the small punch 121 is small, the punch hole surface is prone to plastic deformation due to local compression.

[0124] The adjustment amount at the end of the upper chord 1 is mainly affected and limited by the adjustable length of the vertical web member 3. Since the two ends of the vertical web member 3 are connected by small punches 121, the gap between the small punches 121 and the punch holes is large. Without auxiliary measures, the two punch hole plates will be misaligned vertically. In order to avoid damaging the punch hole surface after using the small punches 121, and to ensure that the small punches 121 are only used as a vertical adjustment control measure when the vertical web member 3 is installed, so that it is not subject to the vertical load of the two punch hole plates, a first support device 6 is set between the vertical web member 3 and the existing lower chord 17, and a second support device 7 is set between the vertical web member 3 and the upper chord 1. The vertical load generated by the self-weight of the upper chord 1 and the vertical web member 3 is transmitted through the first support device 6 → vertical web member 3 → second support device 7 → lower chord 2, eliminating the situation of transmitting the vertical load through the punch hole surface → punch → punch hole surface.

[0125] Similarly, the adjustment amount at the end of the lower chord 2 is mainly affected and limited by the adjustable length of the diagonal web member 4. When installing the lower chord 2 and the diagonal web member 4, in order to avoid damaging the punch hole surface after using the small punch 121, and to ensure that the small punch 121 is only used as a vertical adjustment control measure for the diagonal web member 4 so that it is not subject to the vertical load of the two punch hole plates, a first lifting device 9 is set between the diagonal web member 4 and the upper chord 1, and a third support device 8 is set between the diagonal web member 4 and the lower chord 2, so that the self-weight of the diagonal web member 4 is protected. The generated vertical load is transmitted through the first lifting device 9 and the third support device 8, eliminating the transmission of large loads through the punch hole surface → punch → punch hole surface. At the same time, a second lifting device 10 is set between the upper chord 1 and the lower chord 2. When the upper chord 1 is fixed, it balances the gravity generated by the lower chord 2, and avoids the lower chord 2 from exerting a downward pulling force on the small punch 121 due to its own weight during the adjustment process, which would cause the small punch 121 to be squeezed and damaged by the punch hole surface.

[0126] The aforementioned adjustment auxiliary device facilitates secondary adjustments to each member of the main truss of the steel truss bridge after installation, avoiding the need for welding after positioning each member, thus protecting the punched pin plate and allowing for multiple adjustments. This results in improved operability and installation efficiency.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for installing the main truss of a steel truss bridge, characterized in that, Based on the existing lower chord (17) and the existing upper chord (18), the front end of the existing lower chord (17) extends out of the existing upper chord (18). The installation method includes the following steps: Step S1: Install vertical bracing (3): Install the vertical bracing (3) at the front end of the existing lower chord (17), and set a first support device (6) at the connection between the vertical bracing (3) and the existing lower chord (17). The first support device (6) is used to adjust the vertical relative position between the vertical bracing (3) and the existing lower chord (17). Step S2: Install the upper chord (1): The rear end of the upper chord (1) is connected to the existing upper chord (18), the front part of the upper chord (1) is connected to the vertical web member (3), and a second support device (7) is set at the connection between the vertical web member (3) and the upper chord (1). The second support device (7) is used to adjust the vertical relative position between the vertical web member (3) and the upper chord (1). Step S3: Re-measurement and adjustment of the elevation of the upper chord (1): Measure whether the elevation of the upper chord (1) reaches the theoretical elevation range of the upper chord. If it does not reach the theoretical elevation range, adjust the height of the first support device (6) and / or the second support device (7) to make the elevation of the upper chord (1) reach the theoretical elevation range of the upper chord. Then temporarily lock the upper chord (1). Step S4: Install the lower chord (2): Install the lower chord (2) at the front end of the existing lower chord (17); Step S5: Install the diagonal brace (4): The upper part of the diagonal brace (4) is connected to the upper chord (1), the lower part of the diagonal brace (4) is connected to the front part of the lower chord (2), and a first lifting device (9) is provided between the diagonal brace (4) and the upper chord (1), and a second lifting device (10) is provided between the lower chord (2) and the upper chord (1). A third support device (8) is provided between the diagonal brace (4) and the lower chord (2), and the third support device (8) is used to adjust the relative position between the diagonal brace (4) and the lower chord (2). Step S6: Re-measurement and adjustment of the elevation of the lower chord (2): Measure whether the elevation of the lower chord (2) reaches the theoretical elevation range of the lower chord. If it does not reach the theoretical elevation range, adjust the third support device (8), the first lifting device (9) and the second lifting device (10) to make the elevation of the lower chord (2) reach the theoretical elevation range of the lower chord. Then temporarily lock the lower chord (2). Step S7: Repeat steps S1-S6 to complete the installation of the main truss; The adjustment of the vertical web member (3) and the existing lower chord member (17) in step S1 specifically includes the following steps: S11: The vertical web member (3) is connected to the existing lower chord member (17) through a first punch, and there is a first gap between the first punch and the punch hole of the vertical web member (3); S12: The gap between the vertical web member (3) and the existing lower chord member (17) is filled by the first support device (6); S13: Adjust the support height of the first support device (6) appropriately according to the adjustment direction of the vertical brace (3). If it needs to be lowered, make the upper part of the punch hole of the vertical brace (3) contact the first punch and transfer the first gap to the lower part of the first punch. If it needs to be raised, make the lower part of the punch hole of the vertical brace (3) contact the first punch and transfer the first gap to the upper part of the first punch. The adjustment of the vertical web member (3) and the upper chord member (1) in step S2 specifically includes the following steps: S21: The vertical web member (3) is connected to the upper chord member (1) by a second punch, and there is a second gap between the second punch and the punch hole of the upper chord member (1); S22: The gap between the vertical web member (3) and the upper chord member (1) is filled by the second support device (7); S23: Adjust the support height of the second support device (7) appropriately according to the adjustment direction of the upper chord (1). If it needs to be lowered, make the upper part of the punch hole of the upper chord (1) contact the second punch and transfer the second gap to the lower part of the second punch. If it needs to be raised, make the lower part of the punch hole of the upper chord (1) contact the second punch and transfer the second gap to the upper part of the second punch. The adjustment of the inclined web member (4) and the lower chord member (2) in step S5 specifically includes the following steps: S51: The diagonal web member (4) is connected to the lower chord member (2) through a third punch, and there is a third gap between the third punch and the punch hole of the diagonal web member (4); S52: The gap between the inclined web member (4) and the lower chord member (2) is filled by the third support device (8); S53: Determine the lengthening or shortening of the inclined web member (4) according to the adjustment direction of the lower chord (2), and adjust the support height of the third support device (8) appropriately. If the lower chord (2) needs to be lowered, the inclined web member (4) is lengthened, the upper part of the punch hole of the inclined web member (4) is brought into contact with the third punch, and the third gap is transferred to the lower part of the third punch. If the lower chord (2) needs to be heightened, the inclined web member (4) is shortened, the lower part of the punch hole of the inclined web member (4) is brought into contact with the third punch, and the third gap is transferred to the upper part of the third punch. The first lifting device (9) includes a chain hoist and a sling; The second lifting device (10) consists of a tensioning end (101), a pull rod (102) and a fixed end (103). The tensioning end (101) is connected to the end of the upper chord (1), and the fixed end (103) is connected to the end of the lower chord (2). The pull rod (102) is used to connect the tensioning end (101) and the fixed end (103).

2. The method for installing the main truss of a steel truss bridge according to claim 1, characterized in that, Step S3 further includes: installing a cross brace (5) located below the upper chord (1), the cross brace (5) being used to connect the two vertical web members (3) along the cross section direction of the steel truss bridge.

3. The method for installing the main truss of a steel truss bridge according to claim 1, characterized in that, Step S7 further includes: installing the upper bridge panel (19) and the lower bridge panel (20).

4. The method for installing the main truss of a steel truss bridge according to claim 1, characterized in that, The first support device (6), the second support device (7) and the third support device (8) all include wedges or jacks.

5. The method for installing the main truss of a steel truss bridge according to claim 1, characterized in that, It also includes methods for adjusting the elevation of each member of the main truss: Step A: Determine the diameter of the punch used for adjustment; Step B: Calculate the theoretical height difference adjustment amount for the chord segments based on the selected punch diameter; Step C: Analysis of the adjustable length of the web member; Step D: Set up auxiliary adjustment devices.

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