A method for integral assembly of bridge steel structure segments based on aerial segmental assembly

Abstract

This invention discloses a method for the overall assembly of bridge steel structure segments based on aerial segmental assembly. An aerial work platform is cantilevered on the outer side of the already constructed bridge steel structure, allowing for the assembly of steel structure segments. The assembled segments are then hoisted to the target location for overall welding. Therefore, the construction method described in this invention has minimal impact on maritime and port operations. Furthermore, elevation calculations show that the aerial work platform has no impact on navigation clearance. Moreover, the welding of the assembled segments ensures the same construction quality as the overall segmental hoisting process.

Description

Technical Field

[0001] This invention relates to a method for the integral assembly of bridge steel structure segments, belonging to the field of bridge construction technology. Background Technology

[0002] Before steel structure assembly and construction, the selection of construction plan should focus on the following aspects: water conservancy and flood control assessment of construction plan, impact of temporary measures adopted in construction plan on waterway, and safety of temporary construction measures.

[0003] There are two main methods for assembling bridges: one is the segmental hoisting process, and the other is the bracket assembly process.

[0004] Typically, the segmental hoisting process involves assembling the segments at a temporary assembly site, transporting them by waterway to the bridge site, and then installing the main span segments using a bridge deck crane. The biggest advantages of this process are its maturity, minimal investment in temporary facilities, optimal economic benefits, and improved control over the overall welding quality and linearity of the steel structure. It has precedents across China, such as the Ningbo Sanguantang Bridge.

[0005] However, the segmental hoisting process presents the following difficulties: the transportation of segments on the river, the dredging of the waterway, the difficulty in transporting and launching large segmental components, the occupation of major waterways, and the closure of waterways.

[0006] The scaffolding assembly process involves setting up a temporary support system in the river, assembling segments, and then assembling the entire structure. The main challenge of this method lies in the fact that when using this method in channel bends, especially sharp bends, the design of the temporary support structure is extremely difficult to ensure the safety of the temporary measures. This is because, to ensure the misalignment of the channel bottom lines on both sides of the bend, the span of the beams in the temporary support structure must be large, which in turn affects the navigation clearance. Furthermore, there is the safety hazard of transport vessels colliding with the temporary supports during maritime transport accidents. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by providing a method for the integral assembly of steel structure segments for extra-large bridges. This method involves cantilevering an aerial work platform on the outer side of the already constructed bridge steel structure, allowing for the assembly of steel structure segments on this platform. The assembled segments are then hoisted to the target location for overall welding. Therefore, the construction method described in this invention has minimal impact on maritime and port operations. Furthermore, elevation calculations show that the aerial work platform does not affect navigation clearance. Moreover, the welding of the assembled segments after hoisting ensures the same construction quality as the integral segment hoisting process.

[0008] To achieve the above-mentioned technical objectives, the present invention will adopt the following technical solution:

[0009] A method for assembling bridge steel structure segments based on aerial segmental assembly includes the following steps:

[0010] Step 1: According to the plan, the main bridge steel structure is divided into several steel structure segments, and for each steel structure segment, the corresponding single truss, lower bridge deck system and upper bridge deck system are manufactured.

[0011] Step 2: Using the existing structure of the main bridge steel structure as the supporting foundation, install the platform forward movement equipment;

[0012] Step 3: Install the aerial work platform at the drive end of the platform forward-moving equipment;

[0013] Step 4: Activate the platform forward movement equipment to move the aerial work platform to the target location on the main bridge steel structure, and then stop the platform forward movement equipment.

[0014] Step 5: Transport the single truss, lower bridge deck system, and upper bridge deck system corresponding to the steel structure segment to be assembled to the aerial work platform via the side span;

[0015] Step 6: Complete the overall assembly of the single truss, lower bridge deck system, and upper bridge deck system on the aerial work platform to form the steel structure segment to be assembled;

[0016] Step 7: Hoist the steel structure segments to be assembled to the construction position to connect with the existing structure of the main bridge steel structure, and then use welding to connect the steel structure segments to be assembled with the existing structure of the main bridge steel structure.

[0017] Step 8: Activate the platform forward movement device to move the platform forward movement device to the next target location on the main bridge steel structure;

[0018] Step 9: Repeat steps 4 to 8 until the assembly of the entire main bridge steel structure is completed.

[0019] Preferably, in step two, the platform forward moving device includes a suspension beam, a lateral movement drive mechanism, and lifting jacks; wherein:

[0020] The aforementioned suspension beam spans the existing structure of the main bridge steel structure;

[0021] One end of the aerial work platform is suspended below the suspension beam, while the other end is cantilevered.

[0022] The lateral movement drive mechanism and the lifting jack are both installed on the lower surface of the suspension beam. When the lifting jack is in the retracted state, the lateral movement drive mechanism under the suspension beam can be linked with the aerial work platform. When the lifting jack is in the extended state, the lateral movement drive mechanism under the suspension beam can be disengaged from the aerial work platform.

[0023] Preferably, in step four, the specific movement process of the aerial work platform is as follows:

[0024] Step 4.1: Retract the piston rod of the lifting jack to the first limit position, so that the lateral drive mechanism under the suspension beam is connected to the aerial work platform;

[0025] Step 4.2: The forward-moving lateral drive mechanism causes the aerial work platform to extend relative to the suspended crossbeam until the aerial work platform reaches the target position of the main bridge steel structure.

[0026] Step 4.3: Extend the piston rod of the lifting jack to disengage the lateral drive mechanism under the suspension beam from the aerial work platform;

[0027] Step 4.4: Connect the aerial work platform to the anchoring steel beams installed on both sides of the existing structure of the main bridge steel structure to form a whole.

[0028] Preferably, in step eight, the specific moving process of the platform forward-moving device is as follows:

[0029] Step 8.1: Retract the piston rod of the lifting jack to the first limit position, so that the lateral drive mechanism under the suspension beam is connected to the aerial work platform;

[0030] Step 8.2: Reverse the lateral movement drive mechanism to move the suspension beam toward the cantilever end of the aerial work platform until the suspension beam is placed at the target position b.

[0031] Step 8.3: Dismantle the connection between the aerial work platform and the existing anchoring steel beams on both sides of the main bridge steel structure.

[0032] Preferably, the aerial work platform includes two upper chords, two lower chords, and several diagonal web members.

[0033] Preferably, in the steel structure segment, there is space between the upper chord end and the lower chord end of the single truss to accommodate the end of the aerial work platform.

[0034] Preferably, the ends of the aerial work platform are rectangular, and the upper chord ends and lower chord ends of the single truss have matching rectangular structures.

[0035] Preferably, in step five, a crawler crane is used to transport the single truss, the lower bridge deck system, and the upper bridge deck system to the aerial work platform via the side span.

[0036] Preferably, in step seven, after the overall steel structure segment is assembled on the aerial work platform, the final position adjustment is completed by walking jacks.

[0037] Based on the above-mentioned technical objectives, the present invention has the following advantages compared with the prior art:

[0038] The construction method described in this invention has minimal impact on maritime and port operations. Furthermore, after elevation calculation, the aerial work platform has no impact on navigation clearance. In addition, after the aerial segment hoisting and splicing is completed, the integral segment is welded and assembled to ensure the same construction quality as the integral segment hoisting process. Attached Figure Description

[0039] Figure 1 This is a flowchart of the construction method described in this invention.

[0040] Figure 2 yes Figure 1 A structural diagram of the aerial work platform and platform forwarding equipment used in the project;

[0041] Figure 3 yes Figure 1 A schematic diagram of the installation of the aerial work platform and platform forwarding equipment onto the main bridge steel structure;

[0042] Figure 4 This is a three-dimensional structural diagram of an aerial work platform;

[0043] Figure 5 yes Figure 4 A schematic diagram of the truss system on the side of the aerial work platform;

[0044] Figure 6 yes Figure 4 A schematic diagram of the bottom horizontal connection structure of the aerial work platform;

[0045] Figure 7 yes Figure 4 A schematic diagram of the end-mounted horizontal connection structure of the aerial work platform;

[0046] Figure 8 This is a schematic diagram showing the use of a crawler crane to lift the current steel structure segment to the overhead work platform;

[0047] Figure 9 This is a schematic diagram of the current steel structure segments being assembled on an aerial work platform and installed onto the main bridge steel structure.

[0048] Figure 10 This is a structural schematic diagram of the main bridge steel structure segment;

[0049] In the diagram: 1-1, Upper bridge deck system; 1-2, Lower bridge deck system; 1-3, Upper chord of the left truss of the bridge; 1-4, Lower chord of the left truss of the bridge; 1-5, Upper chord of the right truss of the bridge; 1-6, Lower chord of the right truss of the bridge; 2-1, First left-side anchoring beam; 2-2, Second left-side anchoring beam; 3-1, Right-side platform truss system; 3-1-1, Upper chord of the platform truss; 3-1-2, Straight web members of the platform truss; 3-1-3, Diagonal web members of the platform truss; 3-1-4, Lower chord of the platform truss; 3-1-5, Platform beam connecting plate; 3-2. Left platform truss system; 3-3. Platform bottom bracing; 3-4. Guardrail; 3-5. End bracing; 3-6. Bottom bracing; 3-7. Support beam; 4-1. Suspension beam; 4-2. Lateral movement drive mechanism; 5. Previous main bridge steel structure segment; 6-1. Lower chord anchor point; 6-2. Upper chord anchor point; 7. Main bridge steel structure segment to be constructed; 8. Crawler crane tracks. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specifically stated, the relative arrangement, expressions, and values ​​of components and steps set forth in these embodiments do not limit the scope of the present invention. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0051] like Figures 1 to 10 As shown, the method for integral assembly of bridge steel structure segments based on aerial segmental assembly of the present invention includes the following steps:

[0052] Step 1: According to the plan, the main bridge steel structure is divided into several steel structure segments, and for each steel structure segment, a corresponding single truss, lower bridge deck system 1-2 and upper bridge deck system 1-1 are manufactured.

[0053] Step 2: Using the existing steel structure of the main bridge as a supporting foundation, install the platform relocation equipment; such as... Figure 2As shown, the platform forward movement equipment includes a suspended crossbeam 4-1, a lateral movement drive mechanism 4-2, and a lifting jack; wherein: the suspended crossbeam 4-1 is arranged across the existing structure of the main bridge steel structure; one end of the aerial work platform is suspended and installed below the suspended crossbeam 4-1, and the other end is cantilevered; the lateral movement drive mechanism 4-2 and the lifting jack are both installed on the lower surface of the suspended crossbeam 4-1; when the lifting jack is in the retracted state, the lateral movement drive mechanism 4-2 below the suspended crossbeam 4-1 can be linked and connected with the aerial work platform; when the lifting jack is in the extended state, the lateral movement drive mechanism 4-2 below the suspended crossbeam 4-1 can be disengaged from the aerial work platform.

[0054] The transverse drive mechanism 4-2 adopts a moving trolley that can move along the track. The moving trolley includes two sets, which are symmetrically installed on the lower surface of the suspension beam 4-1. The track includes two tracks, which are supported by the left and right anchor beams respectively and can be lifted by the crawler crane to the corresponding anchor beam of the next construction position. The crawler crane is placed on the upper bridge deck system 1-1 of the current construction position.

[0055] In this invention, the anchoring beam is a temporary connection system, comprising at least two sets. One set is installed on the left truss of the bridge corresponding to the current construction position, serving as the left anchoring beam, and the other set is installed on the right truss of the bridge corresponding to the current construction position, serving as the right anchoring steel beam.

[0056] Step 3: Install the aerial work platform at the drive end of the platform forward-moving equipment;

[0057] The aerial work platform includes a fixed platform end and a cantilever end located at the front end of the fixed platform end; the fixed platform end can be fixedly connected to either the suspension beam 4-1 or the anchoring steel beam.

[0058] Specifically, the aforementioned aerial work platform, such as Figure 4-7 As shown, the system includes a platform truss system, a platform bottom connector 3-3, and an end connector 3-5. The platform truss system comprises two trusses, corresponding to the left platform truss system 3-2 and the right platform truss system 3-1. The left platform truss system 3-2 and the right platform truss system 3-1 have identical structures and are arranged parallel to each other. The tail ends of the left platform truss system 3-2 and the right platform truss system 3-1 are connected as one unit by the end connector 3-5, and the lower chords of the left platform truss system 3-2 and the right platform truss system 3-1 are connected by the platform bottom connector 3-3 at a position close to the end connector 3-5. Wherein:

[0059] The platform truss system includes a platform truss upper chord 3-1-1, a platform truss straight web member 3-1-2, a platform truss diagonal web member 3-1-3, and a platform truss lower chord 3-1-4. The platform truss upper chord 3-1-1 and the platform truss lower chord 3-1-4 are arranged parallel to each other, and the platform truss upper chord 3-1-1 and the platform truss lower chord 3-1-4 are connected by several platform truss straight web members 3-1-2. Adjacent platform truss straight web members 3-1-2 are connected by the platform truss diagonal web members 3-1-3.

[0060] Several platform beam connecting plates 3-1-5 are installed near the tail end of the lower chord of the platform truss 3-1-4. One side of the platform bottom connector 3-3 is connected to the platform beam connecting plate 3-1-5 on the lower chord of the left platform truss system 3-2, and the other side is connected to the platform beam connecting plate 3-1-5 on the lower chord of the right platform truss system 3-1.

[0061] The platform bottom connection 3-3 includes a support beam 3-7 and a bottom horizontal connection 3-6; there are three support beams 3-7, corresponding to the first to the third support beams 3-7, and the second support beam 3-7 is located between the first and third support beams 3-7. The three support beams 3-7 are parallel to each other and equidistant; the bottom horizontal connection 3-6 includes two V-shaped frames that are spliced ​​together. The two ends of the V-shaped frames are connected to the second support beam 3-7, and the apex is connected to the first support beam 3-7 or the third support beam 3-7.

[0062] There are also three platform crossbeam connecting plates 3-1-5; the two ends of the three supporting crossbeams 3-7 are respectively connected to the corresponding platform crossbeam connecting plates 3-1-5 on the corresponding side.

[0063] The end flat bracing 3-5 includes a rectangular outer frame and connecting diagonal braces that connect the two diagonals of the rectangular outer frame respectively; the rectangular outer frame is formed by four members surrounding each other; each connection point is provided with a node plate.

[0064] In the steel structure segment, such as Figure 10 As shown, there is space between the upper chord end and the lower chord end of the single truss to accommodate the end of the aerial work platform. Specifically, the end of the aerial work platform is rectangular, and there is a matching rectangular structure between the upper chord end and the lower chord end of the single truss.

[0065] Furthermore, in this invention, the left-side anchoring beam comprises two rows, one row installed on the upper chord 1-3 of the left-side truss of the bridge, serving as the second left-side anchoring beam 2-2, and the other row installed on the lower chord 1-4 of the left-side truss of the bridge, serving as the first left-side anchoring beam 2-1; the right-side anchoring beam comprises two rows, one row installed on the upper chord 1-5 of the right-side truss of the bridge, and the other row installed on the lower chord 1-6 of the right-side truss of the bridge. Specifically, upper chord anchoring points 6-2 are provided at corresponding positions on the upper chord 1-3 of the left-side truss of the bridge for installing the second left-side anchoring beam 2-2, and lower chord anchoring points 6-1 are provided at corresponding positions on the lower chord 1-4 of the left-side truss of the bridge for installing the first left-side anchoring beam 2-1. Similarly, corresponding anchoring points are also provided at corresponding positions on the right-side truss of the bridge for installing the corresponding anchoring beams.

[0066] Step 4: Activate the platform forward movement equipment to move the aerial work platform to the target location on the main bridge steel structure, and then stop the platform forward movement equipment.

[0067] The specific movement process of the aerial work platform is as follows:

[0068] Step 4.1: Retract the piston rod of the lifting jack to the first limit position, so that the lateral movement drive mechanism 4-2 under the suspension beam 4-1 is connected to the aerial work platform;

[0069] Step 4.2: The forward-moving lateral drive mechanism 4-2 causes the aerial work platform to extend relative to the suspension beam 4-1 until the aerial work platform reaches the target position of the main bridge steel structure.

[0070] Step 4.3: Extend the piston rod of the lifting jack to disengage the lateral drive mechanism 4-2 below the suspension beam 4-1 from the aerial work platform;

[0071] Step 4.4: Connect the aerial work platform to the anchoring steel beams installed on both sides of the existing structure of the main bridge steel structure to form a whole.

[0072] Step 5: Transport the single truss, lower bridge deck system 1-2, and upper bridge deck system 1-1 corresponding to the steel structure segment to be assembled to the aerial work platform via the side span; in Step 5, a crawler crane is used to transport the single truss, lower bridge deck system 1-2, and upper bridge deck system 1-1 to the aerial work platform via the side span.

[0073] Step 6: Complete the overall assembly of the single truss, lower bridge deck system 1-2, and upper bridge deck system 1-1 on the aerial work platform to form the steel structure segment to be assembled;

[0074] Step 7: Hoist the steel structure segments to be assembled to the construction position to connect with the existing structure of the main bridge steel structure. Then, use welding to connect the steel structure segments to be assembled with the existing structure of the main bridge steel structure. In Step 7, after the overall steel structure segments are assembled on the aerial work platform, the final position adjustment is completed by walking jacks.

[0075] Step 8: Activate the platform forward movement device to move the platform forward movement device to the next target location on the main bridge steel structure;

[0076] In step eight, the specific moving process of the platform forward-moving equipment is as follows:

[0077] Step 8.1: Retract the piston rod of the lifting jack to the first limit position, so that the lateral movement drive mechanism 4-2 under the suspension beam 4-1 is connected to the aerial work platform;

[0078] Step 8.2: Reverse the lateral movement drive mechanism 4-2 to drive the suspension beam 4-1 to move toward the cantilever end of the aerial work platform until the suspension beam 4-1 is placed at the target position b.

[0079] Step 8.3: Dismantle the connection between the aerial work platform and the existing anchoring steel beams on both sides of the main bridge steel structure.

[0080] Step 9: Repeat steps 4 to 8 until the assembly of the entire main bridge steel structure is completed.

[0081] Example 1

[0082] This embodiment mainly illustrates the structural design of the aerial work platform, as detailed below:

[0083] (1) Structural design principles

[0084] 1) Meets the bearing capacity requirements under vertical loads.

[0085] The main span of the main bridge steel structure has a beam height of 6 meters. To meet the requirements for aerial assembly of steel structure segments, the height of the aerial work platform will be close to 8 meters. A truss structure system was chosen to enhance the overall load-bearing capacity of the structure. The structural design also references the formwork structure for cantilevered concrete continuous beam construction. However, due to the need for hoisting segmental components, a horizontal connection cannot be installed directly above the cantilever end of the aerial work platform. Therefore, the overall stability of the platform during construction must be considered in the overall truss structure design.

[0086] 2) Meets the bearing capacity requirements under lateral loads.

[0087] Wind protection measures are required for the welding of steel structures of cantilever aerial work platforms. As a result, the cantilever end of the platform will bear a large lateral wind load, which has a significant impact on the overall stability and structural stress of the work platform. The influence of lateral wind load must be fully considered when designing and calculating the work platform.

[0088] 3) Adapting to the influence of bridge cross slope

[0089] The cross section of the super-large bridge has a 2% cross slope, which causes the left and right truss spaces to have different elevations, thus affecting the anchorage structure of the aerial work platform. Therefore, the design of the aerial work platform must consider the rationality of the platform anchorage measures under the influence of the cross slope.

[0090] (2) Structural component design

[0091] The main load-bearing structure of the aerial work platform adopts a truss structure. The main truss chord is HW400×400×13×21, with 10mm steel plates attached to both sides of the upper chord to form a rectangular section. The main truss straight web members are HW300×300×10×15, and the diagonal web members adopt a cross tie rod design. The diagonal web members in front of the lower front support point are made of double-jointed 25a channel steel (limbs facing each other), and the remaining positions are made of double-jointed 20a channel steel (limbs facing each other).

[0092] Double-segment HW400 I-beams are installed below the first three vertical members of the truss to support the crossbeams 3-7, which also serve as the supporting crossbeams 3-7 for the operating platform distribution beams. Diamond-shaped horizontal bracing is installed between the supporting crossbeams 3-7. To increase the overall stability between the left and right trusses, transverse connections (double-segment 20a channel steel) are installed at the ends of the trusses. See the structural design drawings of the aerial work platform for details. Figure 4-7 As shown.

[0093] (3) Structural anchorage design

[0094] The main bridge uses a fully welded steel structure system, so no additional temporary bolt system is required for construction. Therefore, the aerial work platform is connected to the main bridge truss system via welds.

[0095] The boundary constraints of the aerial work platform are provided by "HM700 steel":

[0096] 1) The connecting steel is located on the top plate of the chord. The upper chord is leveled using wedge-shaped pads, and the lower chord is leveled using 30mm steel plates.

[0097] 2) The aerial work platform is connected to the connecting steel sections by the outward cantilever stiffening of the web members, which not only balances the impact of the longitudinal slope on the installation accuracy, but also can adapt to the 2% cross slope requirement of the main truss structure.

[0098] 3) The reaction force of the upper chord is relatively small (less than 300kN), so the wedge-shaped pad is connected by double-sided fillet welds, and no additional welds are set between the steel section and the upper chord;

[0099] 4) The lower chord reaction force is relatively large. The steel section is welded to the lower chord web members to bear the vertical reaction force. A 30mm pad is set between the steel section and the top plate of the lower chord for leveling. Double-sided fillet welds are used for connection to resist the horizontal reaction force.

[0100] 5) Each segment of the upper and lower chords is equipped with a connecting steel section. The upper chord steel section can be welded on site or made in the factory, but the lower chord steel section must be welded in the factory, otherwise the overhead welding connection is more difficult.

[0101] Furthermore, after cleaning the welds on the top chord plate, asphalt paving is poured, which has relatively low requirements for appearance quality. Fillet welds are used to connect the web members of the bottom chord to the connecting steel sections, and to connect the bottom chord plate to the leveling pads. Among these, the fillet welds on the inner web plate and the top plate are cleaned by downward welding, which is relatively easy, while the fillet welds on the outer web plate require upward welding, which is more difficult. The platform anchorage design is as follows... Figure 2 As shown.

[0102] (4) Structural component verification

[0103] Based on the cross-sectional design, structural calculations were performed using Midas software. The external load was considered to be 1600 kN, along with the lateral wind load on the vertical platform, and anchorage loads were applied as needed. Among the members, the double-channel steel structure uses a back-to-back configuration, with an outer edge distance of 270 mm, which is the net distance between the top and bottom plates of the HW300×300×10×15 I-beams.

[0104] Midas' internal force calculations indicate that the maximum stress in each member of the aerial work platform is 139 MPa, which meets the allowable stress control value of 140 MPa. Simultaneously, the overall stability of the aerial work platform was verified using Midas' calculation software. The results show that the stability coefficient of the aerial work platform is 4.3, meeting the structural stability requirements.

[0105] Example 2

[0106] This embodiment mainly illustrates the forward movement of the aerial work platform during bridge construction, as detailed below:

[0107] After the completion of one segment of construction, the aerial work platform is moved to the next segment for further construction. The platform's forward movement equipment is a crucial component of the overall platform structure. Since the platform's overall weight exceeds 60 tons, the crawler cranes used on the bridge deck cannot complete the forward movement. Therefore, the project team designed a track-mounted platform moving device (i.e., the platform forward movement equipment) to facilitate the overall forward movement of the platform.

[0108] like Figure 1As shown, the track-mounted transfer device is set at the anchor beam position. Before the track is laid, 1-2 additional beams are added. At the same time, wedge-shaped steel plates are used to level the track slope. The lifting jack is set below the suspension beam 4-1. After the work platform is lifted as a whole, the track and the traverse trolley are installed. The front moving power device is used to move it forward. After reaching the designated position, it is lowered.

[0109] Example 3

[0110] This embodiment mainly illustrates the main span segment assembly process based on the above-mentioned aerial work platform, and the specific details are as follows:

[0111] 3.1. Segment division of the main span steel structure

[0112] (1) Segment division determination

[0113] Based on the construction progress of the main bridge's steel structure aerial work platform, the project team divided the main bridge's steel structure into segments. The structure of each segment is as follows: Figure 10 As shown, the main bridge segment includes the upper chord 9-1 and the lower chord. A rectangular space 9-3 can be formed between the tail end of the main bridge steel structure segment and the completed main bridge structure. This effectively controls the accumulation of assembly errors during segment assembly and ensures the overall alignment of the steel structure. The upper chord support point rests on the completed main bridge structure, which not only distributes the load of the aerial work platform but also facilitates the adjustment of the overall segment position.

[0114] (2) Determination of cross-sectional shape

[0115] When the upper and lower bridge decks, as well as the upper and lower chords, all have a 2% cross slope, considering the anchoring requirements for the aerial work platform installation, in addition to maintaining the original 2% cross slope of the upper and lower bridge decks, the bottom plate of the upper chord and the upper and lower top plates of the lower chord are adjusted to be horizontal. Simultaneously, to meet the requirements of the aerial work platform, the upper bridge deck is a cantilever plate installed later in section 1-1. After the adjustments are completed, during the construction of the aerial work platform on the main span of the bridge, the lower anchoring beam is located on the top surface of the lower chord (horizontally positioned), and the bottom surface of the lower chord is adjusted to be horizontal to ensure temporary stability during the early stages of truss installation.

[0116] 3.2. Segmental Assembly of Tracked Cranes

[0117] After the aerial work platform is installed, the crawler crane is positioned. The spacing between the bridge deck anchor beams is set at 7 meters. The maximum dimensions of the 100-ton crawler crane are 7780×6350 (length×width) mm. The 7-meter-wide travel space of the crawler crane is sufficient for its movement. At the same time, the anchor beams can also serve as a limiting device for the crawler crane (the end anchor beams are extended), ensuring the safety of the crawler crane during operation. The segmental components are transported to the rear of the crawler crane via bridge deck transport equipment (limiting rails + transport flatbed trucks), where the crawler crane completes the segmental lifting.

[0118] 3.3. Adjustment of walking jack

[0119] After the overall segment is assembled on the aerial work platform, Liye walking jacks complete the final position adjustment. The walking jacks can use the two steps of "lifting" and "pushing" to adjust the elevation and plane position of the overall segment to ensure the accuracy of the overall alignment of the main bridge.

Claims

1. A method for the integral assembly of bridge steel structure segments based on aerial segmental assembly, characterized in that, Includes the following steps: Step 1: According to the plan, the main bridge steel structure is divided into several steel structure segments, and for each steel structure segment, the corresponding single truss, lower bridge deck system and upper bridge deck system are manufactured. Step 2: Using the existing structure of the main bridge steel structure as the supporting foundation, install the platform forward movement equipment; The platform forward movement equipment includes a suspension beam, a lateral movement drive mechanism, and lifting jacks; among which: The aforementioned suspension beam spans the existing structure of the main bridge steel structure; One end of the aerial work platform is suspended below the suspension beam, while the other end is cantilevered. The lateral movement drive mechanism and the lifting jack are both installed on the lower surface of the suspension beam. When the lifting jack is in the retracted state, the lateral movement drive mechanism under the suspension beam can be linked with the aerial work platform. When the lifting jack is in the extended state, the lateral movement drive mechanism under the suspension beam can be disengaged from the aerial work platform. Step 3: Install the aerial work platform at the drive end of the platform forward-moving equipment; Step 4: Activate the platform forward movement equipment to move the aerial work platform to the target location on the main bridge steel structure, and then stop the platform forward movement equipment; the movement of the aerial work platform specifically includes the following steps: Step 4.1: Retract the piston rod of the lifting jack to the first limit position, so that the lateral drive mechanism under the suspension beam is connected to the aerial work platform; Step 4.2: The forward-moving lateral drive mechanism causes the aerial work platform to extend relative to the suspended crossbeam until the aerial work platform reaches the target position of the main bridge steel structure. Step 4.3: Extend the piston rod of the lifting jack to disengage the lateral drive mechanism under the suspension beam from the aerial work platform; Step 4.4: Connect the aerial work platform to the anchoring steel beams installed on both sides of the existing structure of the main bridge steel structure to form a whole; Step 5: Transport the single truss, lower bridge deck system, and upper bridge deck system corresponding to the steel structure segment to be assembled to the aerial work platform via the side span; Step 6: Complete the overall assembly of the single truss, lower bridge deck system, and upper bridge deck system on the aerial work platform to form the steel structure segment to be assembled; Step 7: Hoist the steel structure segments to be assembled to the construction position to connect with the existing structure of the main bridge steel structure, and then use welding to connect the steel structure segments to be assembled with the existing structure of the main bridge steel structure. Step 8: Activate the platform forward movement device to move the platform forward movement device to the next target location on the main bridge steel structure; Step 9: Repeat steps 4 to 8 until the assembly of the entire main bridge steel structure is completed.

2. The method for integral assembly of bridge steel structure segments based on aerial segmental assembly as described in claim 1, characterized in that, In step eight, the specific moving process of the platform forward-moving equipment is as follows: Step 8.1: Retract the piston rod of the lifting jack to the first limit position, so that the lateral drive mechanism under the suspension beam is connected to the aerial work platform; Step 8.2: Reverse the lateral movement drive mechanism to move the suspension beam toward the cantilever end of the aerial work platform until the suspension beam is placed at the target position b. Step 8.3: Dismantle the connection between the aerial work platform and the existing anchoring steel beams on both sides of the main bridge steel structure.

3. The method for integral assembly of bridge steel structure segments based on aerial segmental assembly as described in claim 1, characterized in that, The aerial work platform includes two upper chords, two lower chords, and several diagonal web members.

4. The method for integral assembly of bridge steel structure segments based on aerial segmental assembly as described in claim 3, characterized in that, In the steel structure segment, there is space between the upper chord end and the lower chord end of the single truss to accommodate the end of the aerial work platform.

5. The method for integral assembly of bridge steel structure segments based on aerial segmental assembly as described in claim 4, characterized in that, The aerial work platform has a rectangular end, and the upper chord end and the lower chord end of the single truss have matching rectangular structures.

6. The method for integral assembly of bridge steel structure segments based on aerial segmental assembly as described in claim 1, characterized in that, In step five, a crawler crane is used to transport the single truss, the lower bridge deck system, and the upper bridge deck system to the aerial work platform via the side span.

7. The method for integral assembly of bridge steel structure segments based on aerial segmental assembly as described in claim 1, characterized in that, In step seven, after the overall steel structure segments are assembled on the aerial work platform, the final position adjustment is completed using walking jacks.

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