Construction method of steel box girder cable-stayed bridge main girder

Abstract

The application provides a construction method of a steel box girder cable-stayed bridge main girder, which comprises the following steps: A, positioning and welding of the side span No. n-3 beam segments in sequence; then, positioning and welding of the side span No. 1 beam segment; finally, positioning and welding of the side span No. 2 beam segment; B, removing the temporary connection between the two beam segments at the bridge pier, and installing the beam segment far from the midspan on the support of the bridge pier; C, construction of the beam segment S0, and then temporary consolidation of the beam segment S0 on the cable tower, and moving the crane to the position where the crane front support point is located on the steel beam S0; and D, construction of the midspan No. 1-n beam segments, and synchronous tensioning of the corresponding cable stays on the main span side and the side span side during the construction of each beam segment. The method of the application is the single cantilever assembly method of the steel box girder from the side span to the midspan, the construction is carried out by using the single-side crane, the counterweight trolley is symmetrically arranged at the side span position, the problems of the construction condition limitation and the influence on the construction period are solved, and the structural safety is ensured.

Description

Technical Field

[0001] This invention relates to the field of cable-stayed bridge technology, specifically to a construction method for the main girder of a steel box girder cable-stayed bridge. Background Technology

[0002] The construction of the main girder of a conventional steel box girder cable-stayed bridge generally adopts the double cantilever symmetrical splicing method. That is, after the steel box girder segments are completed in the steel structure processing plant, they are transported to the lifting point at the bridge site by transport ships. Then, the bridge deck cranes lift them simultaneously from both sides of the main tower to ensure the force balance on both sides of the main girder. This also reduces the bending moment at the base of the main tower caused by unbalanced construction of the main girder, and improves the stress on the main tower and its foundation.

[0003] However, some bridges are constrained by construction conditions at their locations, such as shallow water levels, the need to construct the main beams during the dry season, and side spans located on the shore, making it impossible for transport ships to reach the corresponding lifting positions. In such cases, using the conventional symmetrical cantilever assembly method would be impractical due to construction limitations and would significantly impact the construction schedule. Summary of the Invention

[0004] To address the above problems, the present invention provides the following technical solution:

[0005] A construction method for the main girder of a steel box girder cable-stayed bridge includes the following steps:

[0006] Step A: Position and weld beam segments n to 3 of the side span one by one; then position and weld beam segment 1 of the side span; finally position and weld beam segment 2 of the side span.

[0007] Among them, the No. 1 beam segment of the side span is located on the support next to the pier, and the nth to 3rd beam segments of the side span are located on the support of the side span;

[0008] Among them, in the side spans, some side span beam segments from the piers to the middle span are temporarily connected to each other; other segments are welded together.

[0009] The number of side span beam segments is n, and the number of middle span beam segments is n; the side spans and the middle spans are connected by the intermediate segment S0;

[0010] Step B: Remove the temporary connection between the two beam segments at the pier and install the beam segment furthest from the mid-span onto the pier's support;

[0011] Step C: Construct beam segment S0, then temporarily fix it to the cable tower, and move the crane forward until the front support of the crane is located at steel beam S0;

[0012] Step D: Construction of beam segments 1 to n in the middle span. During the construction of each beam segment, the corresponding stay cables on the main span side and the side span side are tensioned simultaneously to enable the middle span to close.

[0013] If the side span beam segment connected by the side cable is previously temporarily connected to the two adjacent beam segments, it is necessary to weld it to the tensioned beam segment before hoisting the beam segment.

[0014] Specifically, it includes:

[0015] Step D1: Lifting, positioning, marking, and welding of beam segment No. 1 in the middle span;

[0016] Step D2: First, release all the remaining temporary connections on the side span. Then, lift, position, mark, and weld the No. 2 beam segment in the middle span. Finally, the No. 1 stay cable is simultaneously tensioned for the first time on the main span side and the side span side.

[0017] Step D3: First, the front support of the crane moves from the side span to the middle span; then, a moving trolley is set up for counterweight; finally, the No. 1 cable-stayed cable is tensioned for the second time on the main span side and the side span side.

[0018] Step D4: First, the No. 3 beam segment in the middle span is lifted, positioned, marked, and welded; then, the No. 2 stay cable is simultaneously tensioned for the first time on the main span side and the side span side.

[0019] Then, the bridge deck crane moves forward towards the middle span, while the counterweight trolley on the side span moves backward to a symmetrical position;

[0020] Finally, the second tensioning was performed on the main span side and the side span side of the No. 2 cable;

[0021] Step D5, repeat step D4, until the construction of all beam segments corresponding to the pre-temporarily connected side spans of the mid-span beam segment is completed;

[0022] Next, construction began on the two span beams at the piers, and the corresponding mid-span beams.

[0023] Finally, the remaining side span beam segments are constructed, corresponding to the middle span beam segments, to complete the closure of the middle span.

[0024] Step E: First, hoist the main beam for closing the middle span so that the middle spans on both sides can be closed.

[0025] Afterwards, the temporary consolidation, crane, mobile trolley, side span support, and pier-side support of the main tower at point S0 were dismantled.

[0026] Finally, the bridge deck was constructed, and the bridge was completed.

[0027] Preferably, step A specifically includes:

[0028] Step A1: Construction of side span supports and pier-side supports for the main tower;

[0029] Among them, a space is formed between the side span support and the main tower pier support for hoisting each section of steel beam to the side span support;

[0030] Step A2: Lifting and splicing crane and crane sliding frame; wherein, the crane is fixed to the crane sliding frame, and the crane moves on the side span support through the crane sliding frame;

[0031] Step A3: Drag the crane sliding bracket and the crane to the support pipe at the front support point of the crane; wherein, the support pipe is pre-fixed to the side span support;

[0032] Step A4: After anchoring the crane to the sliding support, use the crane to lift the nth beam segment of the side span onto the side span support; wherein, the nth beam segment of the side span is located at the end of the side span support closer to the middle span; the steel beam SA12 is located in front of the support pipe;

[0033] Step A5: Drag the whole structure. The crane moves forward passively with the crane sliding support, so that the front support point of the crane is transferred to the nth beam segment of the side span. Cut off the support pipe used to support the front support point of the crane. Drag the nth beam segment of the side span, the crane, and the sliding support backward as a whole.

[0034] Step A6: After the front support of the crane is pulled into place to accommodate the n-1th beam segment of the side span, hoist the n-1th beam segment of the side span to the side span support and weld it to the nth beam segment of the side span.

[0035] Step A7: Move the crane forward until the front support of the crane is located on the (n-1)th beam segment of the side span, remove the crane sliding support, and finally drag the whole crane backward; at this time, the crane has been transferred to the steel beam and can move on the steel beam on its own.

[0036] Step A8: After the whole structure is pulled into place, hoist the n-2nd beam segment of the side span to the side span support and weld it to the n-1st beam segment of the side span.

[0037] Step A9: When the crane moves forward on its own until the front support of the crane is located at the n-2th beam segment of the side span, drag the whole thing backward.

[0038] After the entire structure is towed into place, hoist the n-3rd beam segment of the side span to the side span support, and weld it after matching it with the n-2nd beam segment of the side span.

[0039] Repeat step A9 until the pre-designed beam segment to be pulled to the pier is installed, and the i-th beam segment of the side span away from the middle span is installed; where 4≤i≤n-3;

[0040] Step A10: When the crane moves forward until the front support of the crane is located on the i-th beam segment of the side span, the entire structure is pulled backward.

[0041] Once the entire structure is in place, the i-1th beam segment of the side span is temporarily connected to the ith beam segment of the side span after being matched.

[0042] Step A11: Repeat step A10 until the third beam segment of the side span is matched with the fourth beam segment of the side span and then temporarily connected.

[0043] Preferably, step B specifically includes: moving the crane forward until the front support of the crane is located at the third beam segment of the side span, removing the temporary connection between the i-th beam segment and the (i-1)-th beam segment of the side span; and installing the support under the i-th beam segment of the side span to avoid the i-th beam segment to the n-th beam segment of the side span affecting the tensioning process of other segments of the side span.

[0044] Preferably, step C specifically includes:

[0045] Step C1: Hoist the steel beam S0 to the support frame next to the pier;

[0046] Step C2: After pushing the steel beam S0 into place, hoist the No. 1 beam segment of the side span to the support next to the pier and weld it to the steel beam S0.

[0047] Step C3: Hoist the No. 2 beam segment of the side span and weld the No. 2 beam segment of the side span to the No. 1 beam segment of the side span, and the No. 2 beam segment of the side span to the No. 3 beam segment of the side span;

[0048] Step C4: Temporarily fix the steel beam S0 to the cable tower;

[0049] Step C5: The crane moves forward until the front support of the crane is located on the steel beam S0. At this time, the crane moves to the middle span.

[0050] Preferably, step D1 specifically involves: using a crane to lift the first beam segment of the mid-span to the support next to the pier, and then welding it after matching it with the steel beam S0.

[0051] Preferably, step D3 specifically includes:

[0052] First, the crane was modified to reduce its weight, and then the support frame next to the pier was removed.

[0053] Then, the crane moved forward until its front support was located on the second beam segment of the mid-span.

[0054] Next, a moving trolley is set up on the side span to provide counterweight to simulate the weight of the crane, and its position is consistent with that of the crane on the middle span;

[0055] Finally, the first stay cables A1 and J1 were tensioned for the second time.

[0056] Preferably, step D4 specifically includes:

[0057] The crane lifted the No. 3 beam segment of the middle span, and then welded the No. 3 beam segment of the middle span and the No. 2 beam segment of the middle span; after the welding was completed, the No. 2 stay cables A2 and J2 were tensioned for the first time;

[0058] The crane is moved forward until its front support point is located in the third beam segment of the middle span, and the trolley is moved backward until its front support point is located in the third beam segment of the side span.

[0059] Then, the second tensioning of the second stay cables A2 and J2 was carried out;

[0060] Finally, the No. 1 inclined cable A1 was tensioned for the third time.

[0061] Preferably, step D5 specifically includes:

[0062] Step D51: Weld beam segment 3 and beam segment 4 of the side span;

[0063] The crane lifted the fourth beam segment of the mid-span.

[0064] Welding of beam segment 3 and beam segment 4 in the middle span;

[0065] After welding was completed, the No. 3 stay cables A3 and J3 were tensioned for the first time.

[0066] The crane is moved forward until its front support is located in the 4th beam segment of the middle span, and the moving trolley is moved backward until its front support is located in the 4th beam segment of the side span.

[0067] The second tensioning of cable-stayed cable A3 and J3; the third tensioning of cable-stayed cable A2;

[0068] Repeat the above steps until the second tensioning of cable i-3, Ji-3 and the third tensioning of cable i-4, Ai-4, are completed;

[0069] Step D52: Weld the (i-1)th beam segment of the side span to the ith beam segment of the side span;

[0070] Hoisting the i-1 beam segment in the middle span, and tensioning the i-2 stay cables Ai-2 and Ji-2 for the first time;

[0071] The crane is moved forward until the front support point of the crane is located at the i-1 beam segment of the middle span. The moving trolley remains in its original position, and a heavy object is placed on the moving trolley to perform ballast on the side span.

[0072] The second tensioning of cable i-2, Ai-2 and Ji-2, and the third tensioning of cable i-3, Ai-3;

[0073] Repeat step D52 until the mid-span i-th beam segment is installed, the i-1-th stay cable Ai-1 and Ji-1 are tensioned for the second time, and the i-2-th stay cable Ai-3 is tensioned for the third time;

[0074] Step D531: Hoist the (i+1)th beam segment of the mid-span, and then weld the (i)th beam segment of the mid-span and the (i+1)th beam segment of the mid-span.

[0075] After welding is completed, the i-th stay cable Ai and Ji are tensioned for the first time;

[0076] The crane is moved forward until its front support point is located in beam segment i+1 of the mid-span.

[0077] The second tensioning of cable i, Ai and Ji, and the third tensioning of cable i-1, Ai-1;

[0078] Step D532: Hoist the (i+2)th beam segment of the mid-span, and then weld the (i+1)th beam segment of the mid-span and the (i+2)th beam segment of the mid-span.

[0079] After welding is completed, the i+1 stay cables Ai+1 and Ji+1 are tensioned for the first time.

[0080] The crane is moved forward until its front support point is located in beam segment i+2 of the mid-span.

[0081] The second tensioning of the i+1th stay cable Ai+1 and Ji+1;

[0082] Repeat step D532 until the nth beam segment in the middle span is installed.

[0083] Preferably, step E further includes: a fourth tensioning of the first stay cable A1 and J1.

[0084] Preferably, the construction method is carried out simultaneously on both sides of the center of the main bridge.

[0085] Compared with the prior art, the advantages of the present invention are:

[0086] (1) The construction problem of the main beam of the cable-stayed bridge is solved by using a single cantilever assembly method of steel box girder from the side span to the middle span. With this method, the steel box girder of the side span is welded in advance and erected in advance, which can effectively save more than 3 months of construction time and is not affected by the depth of the water or the dry season. It has good economic benefits.

[0087] (2) The main beam construction method uses a single-sided crane to move from the side span to the middle span. Counterweight trolleys are symmetrically set at the side span. However, due to the weight of the crane on the bridge deck, there is still a certain deviation. Due to the asymmetrical construction, the unbalanced force on both sides of the main beam will gradually accumulate during the construction process, which will lead to unfavorable stress on the tower. In order to ensure the structural safety of the tower, multiple tensioning is carried out. Attached Figure Description

[0088] Figures 1-10 A schematic diagram of the main bridge construction procedures A1-A10;

[0089] Figures 11-13 A schematic diagram of construction procedure A11 for the main bridge;

[0090] Figure 14A schematic diagram of construction procedure B for the main bridge;

[0091] Figures 15-19 A schematic diagram of the main bridge construction procedures C1-C5;

[0092] Figures 20-22 A schematic diagram of the main bridge construction procedures D1-D3;

[0093] Figure 23 A schematic diagram of the main bridge construction sequence D4-D52;

[0094] Figure 24 A schematic diagram of construction sequence D52 for the main bridge;

[0095] Figure 25 A schematic diagram of the main bridge construction sequence D52-D53;

[0096] Figure 26 This is a schematic diagram of construction procedure E for the main bridge. Detailed Implementation

[0097] The present invention will now be described in more detail with reference to the accompanying drawings, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0098] Step A: Position and weld beam segments n to 3 of the side span one by one; then, position and weld beam segment 1 of the side span; finally, position and weld beam segment 2 of the side span; wherein, beam segment 1 of the side span is located on the support next to the pier, and beam segments n to 3 of the side span are located on the support of the side span.

[0099] Among them, in the side spans, some side span beam segments from the piers to the middle span are temporarily connected to each other; other segments are welded together.

[0100] The number of side span beam segments is n, and the number of middle span beam segments is n; the side spans and the middle spans are connected by the intermediate segment S0;

[0101] Step A1: Construction of the side span supports and the pier-side supports of the main tower, such as... Figure 1 As shown.

[0102] Among them, a space is formed between the side span support and the main tower pier support for hoisting each section of steel beam to the side span support;

[0103] Step A2: Lifting and splicing bridge crane and crane sliding frame; such as Figure 2 As shown.

[0104] At this stage, the crane cannot move on its own and must be secured to the crane's sliding frame, which then moves the crane. After the SA11 segment is hoisted, the entire crane is transferred to the steel beam, and then the crane moves on its own from the steel beam.

[0105] The crane's sliding frame and traveling track are positioned in the same direction. This is to address the issue of the crane not being directly anchored to the support and able to travel before the steel beams support it. The sliding frame was designed to solve the initial problems of crane anchoring and travel.

[0106] Step A3: Drag the crane sliding bracket and the crane to the support pipe at the front fulcrum of the crane, as shown. Figure 3 As shown in the figure. The support pipe is pre-fixed to the side span support.

[0107] Before step A7, the crane still needs to be anchored to the sliding support and moved via the sliding support. Without the crane's sliding support, the crane cannot be anchored to the side span support. The towing is achieved by installing four sets of continuous jack systems on the side span support, connected to steel strands and anchor pullers, using the jacks for traction to achieve backward movement.

[0108] Step A4: After anchoring the crane to the sliding support, use the crane to lift the steel beam SA12 onto the side span support. Figure 4 As shown.

[0109] Specifically, steel beam SA12 is located at the end of the side span support near the middle span; steel beam SA12 is located in front of the support pipe;

[0110] "Front direction" refers to the direction closer to the mid-span.

[0111] To stabilize the crane, it needs to be anchored to the sliding support.

[0112] Step A5: Drag the entire assembly (crane + crane sliding bracket). The crane moves forward passively along with the crane sliding bracket, transferring the front support point of the crane to the steel beam SA12. Cut off the support pipe supporting the front support point of the crane, and then drag the steel beam SA12, crane, and sliding bracket backward as a whole. Figure 5 As shown.

[0113] The principle is the same as in step A3. At this point, half of the crane has been transferred to the steel beam, while the other half is still on the sliding frame. The transfer is not yet complete.

[0114] Step A6: After the crane's front support is pulled into position (enough to accommodate one steel beam SA11), hoist steel beam SA11 to the side span support and weld it to steel beam SA12. (Example:) Figure 6 As shown.

[0115] The crane's front support point needs to be supported on a relatively rigid surface such as a diaphragm. "In place" means moving it to the diaphragm position permitted by the design. All support points must be at the diaphragm position; four diaphragms are designed within a single steel beam segment.

[0116] The reason for pulling back is that the SA12 segment needs to be pulled back to make room for the SA11 segment to be placed on the support.

[0117] Step A7: Move the crane forward until its front fulcrum is above the first partition plate of steel beam SA11 near the main tower (cable tower). At this point, remove the sliding support. Finally, drag steel beams SA11 and SA12, along with the crane, backward as a whole. Figure 7 As shown.

[0118] At this point, the bridge crane has been transferred onto the steel beam and can move independently on it. Therefore, the sliding support frame is no longer needed. The main function of the sliding support frame is to provide a platform for anchoring the crane.

[0119] The dragging is done as before, using a jack system.

[0120] Step A8: After the entire structure is pulled into place, hoist steel beam SA10 to the side span support and weld it to steel beam SA11. (The rest of the text appears to be unrelated and possibly machine-translated gibberish.) Figure 8 As shown.

[0121] Step A9: The crane moves forward automatically until its front fulcrum is above the first partition plate of steel beam SA10 near the main tower (cable tower). Then, the steel beams SA12, SA11, SA10, and the crane are pulled backward as a whole. Figure 9 As shown.

[0122] Once the entire structure is in place, the steel beam SA9 is hoisted onto the side span support and then welded to match the steel beam SA10.

[0123] In other words, the fulcrum is moved forward first, then the entire beam is moved backward to make room for the next steel beam. The entire beam must be pulled backward using jacks to create space for the next steel beam to be hoisted.

[0124] Step A10: Move the crane forward until its front fulcrum is above the first partition plate of steel beam SA9 near the main tower (cable tower). Then, drag steel beams SA12, SA11, SA10, SA9, and the crane backward as a whole. Figure 10 As shown.

[0125] Once the entire structure is in place, steel beam SA8 is hoisted to the side span support and matched with steel beam SA9. A temporary connection is then made using rigid clamps or similar materials. This temporary connection is used to minimize losses from cable tensioning and to ensure structural balance on both sides of the tower during the hoisting of the mid-span.

[0126] Step A11: Repeat step A10 until the third beam segment of the side span is matched with the fourth beam segment of the side span and then temporarily connected.

[0127] Specifically:

[0128] Repeat step A10 until steel beam SA5 and steel beam SA6 are matched, then temporarily connected using rigid clamps or similar methods. Figure 11 As shown.

[0129] That is, the connection between SA5 and SA9 all adopts the above-mentioned temporary connection.

[0130] Setting up temporary connections in the tensioning area can be understood as minimizing imbalances during tensioning.

[0131] To improve the stress on the cable tower as much as possible during and after the process.

[0132] like Figure 12 As shown, the crane moves forward until the front support of the crane is above the first partition of the steel beam SA5 near the main tower (cable tower), and then the steel beams SA12 to SA5 and the crane as a whole are dragged backward.

[0133] After the front support of the crane is pulled into place, the steel beam SA4 is hoisted to the side span support, and then welded or temporarily connected to the steel beam SA5.

[0134] like Figure 13 As shown, the crane moves forward until the front support of the crane is above the first partition of the steel beam SA4 near the main tower (cable tower), and then the steel beams SA12 to SA4 and the crane as a whole are dragged backward.

[0135] After the front support of the crane is pulled into place, the steel beam SA3 is hoisted to the side span support and matched with the steel beam SA4. Then, it is welded or temporarily connected using rigid plates or similar means.

[0136] J is the mid-span beam segment, which is in an open area, so welding is required.

[0137] Welding is necessary between SA3 and SA4 because SA2 is the gap section of the side span support. The crane needs to travel from SA4 to SA3, passing through SA2, SA1, etc., and these sections are welded together to meet the stress requirements.

[0138] Step B: Remove the temporary connection between the two beam segments (SA8 and SA9) at the pier, and install the beam segment away from the mid-span onto the pier support.

[0139] like Figure 14 As shown: Check and adjust the position of steel beams SA12 to SA3 to ensure that the design requirements are met.

[0140] Then, the crane moves forward until the front support of the crane is above the second partition plate of the steel beam SA3 near the main tower (cable tower).

[0141] At this point, we are approaching the gap where the steel beam will be lifted (between the pier support and the side span support). If we follow the previous method, the support would still be on the first diaphragm, and the structure would not be able to withstand the stress. Therefore, we need to support it on the second diaphragm.

[0142] Finally, the temporary connection between SA8 and SA9 is removed (in order to move in a symmetrical direction as much as possible for subsequent tensioning).

[0143] Side span support installation: The supports are installed under segment SA9. The temporary connection is released so that segments 9-12 will not affect the tensioning process of segment 8. The supports are permanent and fixed to the pier. Side span supports are located on both sides of the pier.

[0144] Step C: Construct beam segment S0, then temporarily fix it to the cable tower, and move the crane forward until the front support of the crane is located at steel beam S0.

[0145] Step C1, as follows Figure 15 As shown, the steel beam S0 is hoisted to the support next to the pier;

[0146] Step C2, as follows Figure 16 As shown, after pushing the steel beam S0 into place (center, initially on the side), the steel beam SA1 is hoisted to the support next to the pier and matched and welded with the steel beam SA0.

[0147] Finally, steel beams SA1 and S0 were adjusted according to the bridge's design alignment. That is, before welding, the positions of these two beam segments were adjusted based on the longitudinal and transverse slopes.

[0148] Step C3, as follows Figure 17 As shown, steel beam SA2 is hoisted and welded to steel beam SA1 and steel beam SA3.

[0149] Before welding, the beam alignment, elevation, and corresponding mileage of steel beams SA3, SA2, and SA2 were adjusted, taking into account the longitudinal and transverse slopes to ensure that the entire beam was smooth in the bridge direction.

[0150] Step C4, as follows Figure 18 As shown, the mileage and elevation values ​​of steel beam S0 are determined, and steel beam S0 on the pier top is temporarily fixed; it is temporarily fixed on the pylon to ensure the safety of the main beam under stress during cantilever construction.

[0151] Step C5, as follows Figure 19 As shown, the crane moves forward until its front support point is located on steel beam S0, at which point the crane moves to the middle span.

[0152] Step D: Construction of beam segments 1 to n in the middle span. During the construction of each beam segment, the corresponding stay cables on the main span side and the side span side are tensioned simultaneously to enable the middle span to close.

[0153] If the side span beam segment connected by the side cable is previously temporarily connected to the two adjacent beam segments, it is necessary to weld it to the tensioned beam segment before hoisting the beam segment.

[0154] Step D1: Lifting, positioning, marking, and welding of the first beam segment in the middle span.

[0155] like Figure 20 As shown, the crane lifts the steel beam SJ1 to the support next to the pier, and then welds it to the steel beam S0.

[0156] Step D2: Release all temporary connections on the side spans. Then, lift, position, mark, and weld the No. 1 beam segment in the middle span. Finally, the No. 1 stay cable is simultaneously tensioned for the first time on the main span side and the side span side.

[0157] like Figure 21 As shown, first disconnect the temporary connections between steel beam SA3 and steel beam SA4, steel beam SA5 and steel beam SA6, steel beam SA6 and steel beam SA7, and steel beam SA7 and steel beam SA8.

[0158] Afterwards, the crane lifted steel beam SJ2, which was then matched with steel beam SJ1 and welded together.

[0159] First release it, then hoist SJ2. This is also to ensure that the hoisting and tensioning are done in a symmetrical direction as much as possible.

[0160] Finally, the stay cables A1 and J1 were tensioned for the first time; among them, stay cable A1 connects the tower and the steel beam SA2, and stay cable J1 connects the tower and the steel beam SJ2.

[0161] Figure 21 Compared to version 20, the front support point did not move forward to SJ1 for two reasons: firstly, for balance, and secondly, for stress. At this point, the crane had not yet undergone weight reduction modifications, and the force was relatively large. Moving it forward would have caused the steel beam to be unable to withstand the localized stress.

[0162] Step D3: The front support of the crane moves from the side span to the middle span;

[0163] Then, a mobile trolley is set up for counterweight application;

[0164] Finally, the second tensioning was performed on the main span side and the side span side of the No. 2 cable;

[0165] like Figure 22 As shown, the crane was modified to reduce its weight, and then the support next to the pier was removed.

[0166] Then, the crane moves forward until the front support of the crane is above the second diaphragm of the steel beam SJ2, away from the main tower (cable tower).

[0167] Next, a mobile trolley was set up on the side span to provide counterweight and simulate the weight of the crane. The front support point of the mobile trolley was located above the second diaphragm of steel beam SA2 away from the main tower (cable tower), that is, it was aligned with the crane position on the middle span.

[0168] Finally, the stay cables A1 and J1 were tensioned a second time. After rebalancing and moving the tower, an unbalanced moment was generated.

[0169] Step D4: Lifting, positioning, marking, and welding of beam segment No. 3 in the middle span; simultaneous first tensioning of cable No. 2 on the main span side and side span side;

[0170] The bridge deck crane moves forward towards the middle span, while the counterweight trolley on the side span moves forward to a symmetrical position.

[0171] Second tensioning of the No. 2 cable-stayed cable on the main span and side span sides;

[0172] like Figure 23 As shown: Step (1) The crane lifts the steel beam SJ3, adjusts the alignment, elevation and mileage of the steel beam SJ3, and then welds SJ3 and SJ2.

[0173] After welding, the stay cables A2 and J2 are tensioned for the first time. Stay cable A2 connects the tower to the steel beam SA3, and stay cable J2 connects the tower to the steel beam SJ3.

[0174] The crane is moved forward until its front support point is located above the second partition of SJ3, which is furthest from the main tower (cable tower).

[0175] The moving trolley is moved back to the position above the second partition of SA3, which is away from the main tower (socket tower).

[0176] The second tensioning of cable stays A2 and J2 was performed. After they were in place, the third tensioning of cable stay A1 was performed.

[0177] The middle span does not require a third tensioning. Because the side spans are constructed in advance, and the cranes are not symmetrically positioned but travel from the side spans to the middle span, the unbalanced forces are mainly caused by the side spans (since the side spans were constructed in advance, and the middle span was constructed later, resulting in a weight mismatch). Therefore, the third tensioning is to further eliminate its influence.

[0178] Step D5, repeat step D4, until all beam segments corresponding to the pre-temporarily connected side spans of the mid-span beam segment are constructed.

[0179] Next, construction began on the two span beams at the piers, and the corresponding mid-span beams.

[0180] Finally, construct the remaining side span beam segments corresponding to the middle span beam segments to complete the middle span closure:

[0181] Step D51, repeating step D4, involves the construction of all pre-temporarily connected beam segments in the mid-span corresponding to the side spans:

[0182] like Figure 23 As shown, (2) Adjust the line type, elevation and mileage of SA4 and SA5, and weld SA3 and SA4.

[0183] The crane lifted steel beam SJ4, adjusted the alignment, elevation and mileage of steel beam SJ4, and then welded the circumferential joints of SJ3 and SJ4.

[0184] After welding, the stay cables A3 and J3 were tensioned for the first time. Stay cable A3 connects the tower and the steel beam SA4, and stay cable J3 connects the tower and the steel beam SJ4.

[0185] The crane is moved forward until its front support point is located above the second partition of SJ4, away from the main tower (cable tower).

[0186] The moving trolley is moved back to the position above the second partition of SA4, which is away from the main tower (socket tower).

[0187] The second tensioning of cable stays A3 and J3 was performed. After they were in place, the third tensioning of cable stay A2 was performed.

[0188] like Figure 23 As shown, (3) the crane lifts the steel beam SJ5, adjusts the alignment, elevation and mileage of the steel beam SJ5, and then welds the circumferential joints of SJ4 and SJ5.

[0189] After welding, the stay cables A4 and J4 were tensioned for the first time. Stay cable A4 connects the tower to the steel beam SA5, and stay cable J4 connects the tower to the steel beam SJ5.

[0190] The crane is moved forward until its front support point is located above the second partition of SJ5, which is furthest from the main tower (cable tower).

[0191] The moving trolley is moved back to the position above the second partition of SA5, which is away from the main tower (socket tower).

[0192] The second tensioning of cable stays A4 and J4 was performed. After they were in place, the third tensioning of cable stay A3 was performed.

[0193] like Figure 23 As shown, (4) Adjust the SA6 alignment, elevation and mileage, and weld the SA5 and SA6 ring joints.

[0194] The crane lifted steel beam SJ6, adjusted its alignment, elevation, and mileage, and then welded the circumferential joints of SJ5 and SJ6.

[0195] After welding, the stay cables A5 and J5 were tensioned for the first time. Stay cable A5 connects the tower to the steel beam SA6, and stay cable J5 connects the tower to the steel beam SJ6.

[0196] The crane is moved forward until its front support point is located above the second partition of SJ6, which is furthest from the main tower (cable tower).

[0197] The moving trolley is moved back to the position above the second partition of SA6, which is away from the main tower (socket tower).

[0198] The second tensioning of cable stays A5 and J5 was performed. After they were in place, the third tensioning of cable stay A4 was performed.

[0199] Repeat the above steps until SA7 / SJ7-SA8 / SJ8 is installed.

[0200] Step D52, Construction of the two span beam segments at the piers, and the corresponding middle span beam segment:

[0201] Afterwards, the SA8 segment was welded to SA9, SJ8 was hoisted, and the stay cables A7 and J7 were tensioned for the first time. At this point, the front support point of the moving trolley was located above the second partition plate of SA7, which was furthest from the main tower (tower).

[0202] like Figure 24 The crane is moved forward until its front support point is located above the second partition plate of SJ8, which is furthest from the main tower (cable tower). The moving trolley remains in its original position, and heavy objects are placed on the moving trolley to weigh down the side spans in order to balance the imbalance caused by the crane in the middle span.

[0203] The second tensioning of cable stays A7 and J7 was carried out. After they were in place, the third tensioning of cable stay A6 was carried out.

[0204] Figure 25 As shown, (1) repeat the above steps to install to SJ10. This refers to the steps of installing SA8 until SJ9 is installed. Because these sections of the side span are the first ones that have already been welded.

[0205] Step D531: Construct the middle span beam segment corresponding to the remaining side span beam segment to achieve the closure of the middle span:

[0206] Figure 25 As shown, (1) hoist SJ10, adjust the alignment, elevation and mileage of steel beam SJ10, and then weld the circumferential joints of SJ9 and SJ10.

[0207] After welding, the stay cables A9 and J9 were tensioned for the first time. Stay cable A9 connects the tower to the steel beam SA10, and stay cable J9 connects the tower to the steel beam SJ10.

[0208] The crane is moved forward until its front support point is located above the second partition of SJ10, which is furthest from the main tower (cable tower).

[0209] The second tensioning of cable stays A9 and J9 was performed. After they were in place, the third tensioning of cable stay A8 was performed.

[0210] Step D532 Figure 25 As shown, (2) hoist SJ11, adjust the alignment, elevation and mileage of steel beam SJ11, and then weld the circumferential joints of SJ10 and SJ11.

[0211] After welding, the stay cables A10 and J10 were tensioned for the first time. Stay cable A10 connects the tower and the steel beam SA11, and stay cable J10 connects the tower and the steel beam SJ11.

[0212] The crane is moved forward until its front support point is located above the second partition of SJ11, away from the main tower (cable tower).

[0213] The second tensioning of cable stays A10 and J10.

[0214] Repeat the above steps to complete the installation of SJ12.

[0215] Step E: hoisting the mid-span closure main beam, removing the temporary consolidation at s0, dismantling the crane, moving the trolley and side span supports, and the pier-side supports of the main tower.

[0216] like Figure 26 As shown, this allows the side span supports to detach (from the main beam), and the middle span to be hoisted to close the main beam.

[0217] The temporary fixing at point S0 of the main girder is removed, the main tower and main girder supports are in place, and the system is converted. During the hoisting process, the main girder was temporarily fixed at the tower location. Now that the main girder construction is complete, the permanent supports designed in the design will be installed. This is a standard procedure for cantilever bridge construction.

[0218] Dismantle the crane, mobile trolley, side span supports, and pier supports of the main tower.

[0219] The fourth tensioning of the cable-stayed cables A1 and A2.

[0220] Construction of the bridge deck system and ancillary facilities. Final coat of paint applied to the entire bridge.

[0221] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A construction method for the main girder of a steel box girder cable-stayed bridge, characterized in that, Includes the following steps: Step A: Position and weld beam segments n to 3 of the side span one by one; then position and weld beam segment 1 of the side span; finally position and weld beam segment 2 of the side span. Among them, the No. 1 beam segment of the side span is located on the support next to the pier, and the nth to 3rd beam segments of the side span are located on the support of the side span; Among them, in the side spans, some side span beam segments from the piers to the middle span are temporarily connected to each other; other segments are welded together. The number of side span beam segments is n, and the number of middle span beam segments is n; the side spans and the middle spans are connected by an intermediate segment S0; Specifically, it includes: Step A1: Construction of side span supports and pier-side supports for the main tower; Among them, a space is formed between the side span support and the main tower pier support for hoisting each section of steel beam to the side span support; Step A2: Lifting and splicing crane and crane sliding frame; wherein, the crane is fixed to the crane sliding frame, and the crane moves on the side span support through the crane sliding frame; Step A3: Drag the crane sliding bracket and the crane to the support pipe at the front support point of the crane; wherein, the support pipe is pre-fixed to the side span support; Step A4: After anchoring the crane to the sliding support, use the crane to lift the nth beam segment of the side span onto the side span support; wherein, the nth beam segment of the side span is located at the end of the side span support closer to the middle span; the steel beam SA12 is located in front of the support pipe; Step A5: Drag the whole structure. The crane moves forward passively with the crane sliding support, so that the front support point of the crane is transferred to the nth beam segment of the side span. Cut off the support pipe used to support the front support point of the crane. Drag the nth beam segment of the side span, the crane, and the sliding support backward as a whole. Step A6: After the front support of the crane is pulled into place to accommodate the n-1th beam segment of the side span, hoist the n-1th beam segment of the side span to the side span support and weld it to the nth beam segment of the side span. Step A7: Move the crane forward until the front support of the crane is located on the (n-1)th beam segment of the side span, remove the crane sliding support, and finally drag the whole crane backward; at this time, the crane has been transferred to the steel beam and can move on the steel beam on its own. Step A8: After the whole structure is pulled into place, hoist the n-2nd beam segment of the side span to the side span support and weld it to the n-1st beam segment of the side span. Step A9: When the crane moves forward on its own until the front support of the crane is located at the n-2th beam segment of the side span, drag the whole thing backward. After the entire structure is towed into place, hoist the n-3rd beam segment of the side span to the side span support, and weld it after matching it with the n-2nd beam segment of the side span. Repeat step A9 until the pre-designed beam segment to be pulled to the pier is installed, and the i-th beam segment of the side span away from the middle span is installed; where 4≤i≤n-3; Step A10: When the crane moves forward until the front support of the crane is located on the i-th beam segment of the side span, the entire structure is pulled backward. Once the entire structure is in place, the i-1th beam segment of the side span is temporarily connected to the ith beam segment of the side span after being matched. Step A11: Repeat step A10 until the third beam segment of the side span is matched with the fourth beam segment of the side span and then temporarily connected. Step B: Remove the temporary connection between the two beam segments at the pier and install the beam segment furthest from the mid-span onto the pier's support; Step C: Construct beam segment S0, then temporarily fix it to the cable tower, and move the crane forward until the front support of the crane is located at steel beam S0; Step D: Construction of beam segments 1 to n in the middle span. During the construction of each beam segment, the corresponding stay cables on the main span side and the side span side are tensioned simultaneously to enable the middle span to close. If the side span beam segment connected by the side cable is previously temporarily connected to the two adjacent beam segments, it is necessary to weld it to the tensioned beam segment before hoisting the beam segment. Specifically, it includes: Step D1: Lifting, positioning, marking, and welding of beam segment No. 1 in the middle span; Step D2: First, release all the remaining temporary connections on the side span. Then, lift, position, mark, and weld the No. 2 beam segment in the middle span. Finally, the No. 1 stay cable is simultaneously tensioned for the first time on the main span side and the side span side. Step D3: First, the front support of the crane moves from the side span to the middle span; then, a moving trolley is set up for counterweight; finally, the No. 1 cable-stayed cable is tensioned for the second time on the main span side and the side span side. Step D4: First, the No. 3 beam segment in the middle span is lifted, positioned, marked, and welded; then, the No. 2 stay cable is simultaneously tensioned for the first time on the main span side and the side span side. Then, the bridge deck crane moves forward towards the middle span, while the counterweight trolley on the side span moves backward to a symmetrical position; Finally, the second tensioning was performed on the main span side and the side span side of the No. 2 cable; Step D5, repeat step D4, until the construction of all beam segments corresponding to the pre-temporarily connected side spans of the mid-span beam segment is completed; Next, construction began on the two span beams at the piers, and the corresponding mid-span beams. Finally, construct the middle span beam segment corresponding to the remaining side span beam segment to complete the middle span closure; Step E: First, hoist the main beam for closing the middle span so that the middle spans on both sides can be closed. Afterwards, the temporary consolidation, crane, mobile trolley, side span support, and pier-side support of the main tower at point S0 were dismantled. Finally, the bridge deck was constructed, and the bridge was completed.

2. The construction method for the main girder of a steel box girder cable-stayed bridge according to claim 1, characterized in that, Step B specifically includes: moving the crane forward until the front support of the crane is located at the No. 3 beam segment of the side span, removing the temporary connection between the No. 1 beam segment and the (i-1) beam segment of the side span; and installing the support under the No. 1 beam segment of the side span to avoid the tensioning process of other segments of the side span being affected by the No. 1 beam segment to the nth beam segment of the side span.

3. The construction method for the main girder of a steel box girder cable-stayed bridge according to claim 1, characterized in that, Step C specifically includes: Step C1: Hoist the steel beam S0 to the support frame next to the pier; Step C2: After pushing the steel beam S0 into place, hoist the No. 1 beam segment of the side span to the support next to the pier and weld it to the steel beam S0. Step C3: Hoist the No. 2 beam segment of the side span and weld the No. 2 beam segment of the side span to the No. 1 beam segment of the side span, and the No. 2 beam segment of the side span to the No. 3 beam segment of the side span; Step C4: Temporarily fix the steel beam S0 to the cable tower; Step C5: The crane moves forward until the front support of the crane is located on the steel beam S0. At this time, the crane moves to the middle span.

4. The construction method for the main girder of a steel box girder cable-stayed bridge according to claim 1, characterized in that, Step D1 specifically involves: using a crane to lift the No. 1 beam segment of the mid-span to the support next to the pier, and then welding it after matching it with the steel beam S0.

5. The construction method for the main girder of a steel box girder cable-stayed bridge according to claim 1, characterized in that, Step D3 specifically involves: First, the crane was modified to reduce its weight, and then the support frame next to the pier was removed. Then, the crane moved forward until its front support was located on the second beam segment of the mid-span. Next, a moving trolley is set up on the side span to provide counterweight to simulate the weight of the crane, and its position is consistent with that of the crane on the middle span; Finally, the first stay cables A1 and J1 were tensioned for the second time.

6. The construction method for the main girder of a steel box girder cable-stayed bridge according to claim 1, characterized in that, Step D4 is as follows: The crane lifted the No. 3 beam segment of the middle span, and then welded the No. 3 beam segment of the middle span and the No. 2 beam segment of the middle span; after the welding was completed, the No. 2 stay cables A2 and J2 were tensioned for the first time; The crane is moved forward until its front support point is located in the third beam segment of the middle span, and the trolley is moved backward until its front support point is located in the third beam segment of the side span. Then, the second tensioning of the second stay cables A2 and J2 was carried out; Finally, the No. 1 inclined cable A1 was tensioned for the third time.

7. The construction method for the main girder of a steel box girder cable-stayed bridge according to claim 1, characterized in that, Step D5 is as follows: Step D51: Weld beam segment 3 and beam segment 4 of the side span; The crane lifted the fourth beam segment of the mid-span. Welding of beam segment 3 and beam segment 4 in the middle span; After welding was completed, the No. 3 stay cables A3 and J3 were tensioned for the first time. The crane is moved forward until its front support is located in the 4th beam segment of the middle span, and the moving trolley is moved backward until its front support is located in the 4th beam segment of the side span. The second tensioning of cable-stayed cable A3 and J3; the third tensioning of cable-stayed cable A2; Repeat the above steps until the second tensioning of cable i-3, cable i-3 and cable i-3, and the third tensioning of cable i-4, cable i-4, are completed; Step D52: Weld the (i-1)th beam segment of the side span to the ith beam segment of the side span; Hoisting the i-1 beam segment in the middle span, and tensioning the i-2 stay cables A i-2 and J i-2 for the first time; The crane is moved forward until the front support point of the crane is located at the i-1 beam segment in the middle span. The moving trolley remains in its original position, and a heavy object is placed on the moving trolley to perform ballast on the side span. The second tensioning of cable i-2 and cable i-2, and the third tensioning of cable i-3, cable i-3; Repeat step D52 until the mid-span i-th beam segment is installed, the i-1-th stay cable A i-1 and J i-1 are tensioned for the second time, and the i-2-th stay cable A i-3 is tensioned for the third time; Step D531: Hoist the (i+1)th beam segment of the mid-span, and then weld the (i)th beam segment of the mid-span and the (i+1)th beam segment of the mid-span. After welding is completed, the i-th stay cable Ai and Ji are tensioned for the first time; The crane is moved forward until its front support point is located in beam segment i+1 of the mid-span. The second tensioning of cable i, A i and J i, and the third tensioning of cable i-1, A i-1; Step D532: Hoist the (i+2)th beam segment of the mid-span, and then weld the (i+1)th beam segment of the mid-span and the (i+2)th beam segment of the mid-span. After welding is completed, the i+1 stay cables Ai+1 and Ji+1 are tensioned for the first time. The crane is moved forward until its front support point is located in beam segment i+2 of the mid-span. The second tensioning of the (i+1)th stay cable A i+1 and J i+1; Repeat step D532 until the nth beam segment in the middle span is installed.

8. The construction method for the main girder of a steel box girder cable-stayed bridge according to claim 1, characterized in that, Step E also includes: the fourth tensioning of the first stay cable A1 and J1.

9. The construction method for the main girder of a steel box girder cable-stayed bridge according to claim 1, characterized in that, This construction method was carried out simultaneously on both sides of the center of the main bridge.

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