Construction method for reconstructing a suspender arch bridge by using a steel truss beam

Abstract

The application discloses a construction method for transforming a suspender arch bridge by adopting a steel truss beam, and comprises the following steps: constructing pile foundations, bearing platforms and lower pier column segments; installing a combined support; installing a lower truss beam on the combined support; sequentially horizontally pushing and vertically lifting the lower truss beam to a designed position; installing an upper truss beam on the original bridge beam correspondingly and connecting the lower truss beam and the upper truss beam into an integral steel truss beam; installing upper pier column segments and a bent cap; lifting the steel truss beam to complete system conversion and removing the combined support. The lower structure installed in sections and the combined support are combined into a steel truss beam to provide a construction platform for horizontal pushing and vertical lifting of the steel truss beam, and the assembled steel truss beam structure is connected with the original bridge beam into an integral whole, so that the system conversion from the original suspender arch bridge to a new beam bridge is realized quickly and stably, the construction difficulty is reduced, and the transformation construction effect is ensured.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology. More specifically, this invention relates to a construction method for converting a steel truss girder into a suspension arch bridge. Background Technology

[0002] Suspension arch bridges employing a longitudinal and transverse beam stiffening system are prone to structural defects due to deficiencies in their design concepts and methods, as well as external human and environmental factors, posing safety and service life risks. Common modification methods include adding longitudinal beams and replacing hangers. While these direct material reinforcement measures can enhance the bridge's load-bearing capacity to some extent, they cannot fundamentally address the original structural design problems or defects. A more advanced modification method involves transforming the suspension arch bridge into a beam bridge by using steel truss girders and altering the overall structure. This method requires high precision and control during construction, and the quality of construction has a decisive impact on the final result, presenting challenges such as high construction difficulty and difficulty in guaranteeing the modification's effectiveness.

[0003] To address the aforementioned issues, a construction method is needed to modify a suspension arch bridge using steel trusses, thereby reducing construction difficulty while ensuring the quality of the modified bridge. Summary of the Invention

[0004] The purpose of this invention is to provide a construction method for converting a suspended arch bridge using steel truss girders. By combining the segmented installation of the substructure with the combined support structure, a construction platform is provided for the lateral pushing and longitudinal lifting of the steel truss girders. In conjunction with the prefabricated steel truss girder structure, it is connected to the original bridge crossbeams as a whole, thereby quickly and stably realizing the system conversion from the original suspended arch bridge to the new beam bridge, reducing the construction difficulty while ensuring the effectiveness of the conversion construction.

[0005] To achieve these objectives and other advantages according to the present invention, a construction method for modifying a suspension arch bridge using steel truss girders is provided, comprising:

[0006] S1. Construct multiple pile foundations along the length of the bridge, and install corresponding pile caps and lower pier column segments on the pile foundations;

[0007] S2. Install a combined bracket above the lower pier segment, with its bottom fixedly sleeved on the side wall of the lower pier segment.

[0008] S3. Install the lower truss segments on the combined support outside the bridge projection plane and connect them in pairs along the length of the bridge to form a whole, thus completing the installation of the lower truss.

[0009] S4. Push the lower truss beam laterally on the combined support to the designed position;

[0010] S5, vertically jacking the lower truss on the combined support to abut with the bottom of the original bridge beam;

[0011] S6, installing the upper truss segment on the top of the original bridge beam, which corresponds to the lower truss segment, connecting the upper truss segment and the lower truss segment as a whole, that is, completing the assembly of the steel truss;

[0012] S7, constructing the upper pier segment and the bent cap on the top of the lower pier segment;

[0013] S8, integrally jacking the steel truss, and after completing the system conversion, falling the beam, and then removing the combined support, that is, completing the reconstruction of the bowstring arch bridge.

[0014] Preferably, in the construction method for reconstructing the bowstring arch bridge by using the steel truss, the combined support comprises a three-dimensional frame, which is a hollow structure sleeved on the outer wall of the lower pier segment and extends upward along the height direction thereof; two support beams are fixed on the top of the three-dimensional frame on both sides, and any support beam is arranged horizontally along the bridge width direction and extends from the outside of the bridge projection plane to the inside of the bridge projection plane; a track is arranged on the support beam along the length direction, and the lower truss segment is arranged on the track and is in sliding connection with the track; a pushing device is arranged on the track and is used to drive the lower truss to move on the support beam; a jacking device is arranged on the support beam and is located at the designed position of the lower truss, and the jacking device is used to control the height position of the lower truss.

[0015] Preferably, in the construction method for reconstructing the bowstring arch bridge by using the steel truss, the combined support further comprises a limiting device arranged at the end of the support beam located in the bridge projection plane, and the limiting device is used to limit the transverse displacement of the lower truss segment on the track.

[0016] Preferably, in the construction method for reconstructing the bowstring arch bridge by using the steel truss, the number of the combined supports is greater than or equal to the number of the lower pier segments, the combined supports correspond to the bowstring anchor heads one by one and are arranged directly below the bowstring anchor heads; the combined supports are divided into direct supports and indirect supports according to the connection mode, the direct supports correspond to the lower pier segments one by one and are fixedly connected, and the indirect supports are arranged between two adjacent direct supports and are connected to the adjacent direct supports as a whole through the corresponding lower truss segments.

[0017] Preferably, in the construction method for reconstructing the bowstring arch bridge by using the steel truss, the designed position is located on the inner side of the original bridge arch rib and the original bridge longitudinal beam.

[0018] Preferably, in the method for reconstructing a suspender arch bridge by using a steel truss beam, the lower truss beam segment and the upper truss beam segment are sequentially installed along a direction from a bridge side span to a bridge midspan in S3 and S6.

[0019] Preferably, in the method for reconstructing a suspender arch bridge by using a steel truss beam, the upper pier segment and the lower pier segment are a pier structure continuously arranged along a vertical direction, and the upper pier segment is connected to the lower pier segment through a connecting key in S7.

[0020] Preferably, in the method for reconstructing a suspender arch bridge by using a steel truss beam, the step of system conversion in S8 comprises:

[0021] S81, the steel truss beam is integrally jacked up to unload suspender cable force;

[0022] S82, a support is installed between the bent cap and the jacked-up steel truss beam;

[0023] S83, the jacking force on the steel truss beam is gradually reduced to fall the beam, until the steel truss beam is completely supported on the support, that is, the system conversion is completed.

[0024] The present application at least includes the following beneficial effects:

[0025] 1. The present application provides a construction platform for lateral jacking and longitudinal jacking of a steel truss beam by combining a segmented lower structure with a combined support, and integrates the original bridge beam with the added steel truss beam by cooperating with the upper and lower assembled steel truss beam structure, thereby quickly and stably realizing the system conversion of the original suspender arch bridge-new beam bridge. The structure combining the combined support with the lower structure allows precise positioning of the steel truss beam through lateral jacking and longitudinal jacking, reduces the initial installation precision requirement of the lower structure and the steel truss beam, ensures the final installation precision of each component while reducing the difficulty of water construction, thereby effectively solving the construction precision problem of reconstructing a suspender arch bridge with a longitudinal and lateral beam stiffening beam system by using a steel truss beam. At the same time, the combined support structure used in the reconstruction is simple and convenient to disassemble, can make the whole reconstruction construction process controllable, effectively improves the construction stability and safety, and ensures the reconstruction effect, improves the operation safety of the reconstructed bridge.

[0026] 2、The construction method has good universality and applicability, can be widely applied to reconstruction construction of hanger arch bridges of various structures and forms, the steel truss beam system after reconstruction is combined with the longitudinal beam stiffening beam system of the original hanger arch bridge to support the bridge deck system, good reinforcement effect is achieved, the original bridge foundation structure is not changed, the influence of reconstruction construction on the original bridge traffic operation is minimized, after reconstruction is completed, the stress of the original bridge hanger is greatly reduced, the possibility of safety accidents caused by aging of the original bridge hanger system and other factors is reduced, which is beneficial to prolong the service life of the old bridge and ensure the use safety.

[0027] Other advantages, objects and features of the present application will be apparent from the following description, and will be understood by those skilled in the art. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A flow chart of a construction method for reconstructing a hanger arch bridge by using a steel truss beam for one embodiment of the present application;

[0029] Figure 2 A construction plane structure schematic diagram for reconstructing a hanger arch bridge by using a steel truss beam in the above embodiment;

[0030] Figure 3 A construction elevation structure schematic diagram for reconstructing a hanger arch bridge by using a steel truss beam in the above embodiment;

[0031] Figure 4 A side elevation structure schematic diagram of the combined support described in the above embodiment.

[0032] BRIEF DESCRIPTION OF DRAWINGS

[0033] 1, steel truss beam; 11, upper truss beam; 12, lower truss beam; 2, lower structure; 21, upper pier column segment; 22, lower pier column segment; 23, support; 3, combined support; 31, three-dimensional frame; 32, support beam; 33, sliding block; 34, jacking device; 4, original bridge arch rib; 5, original bridge longitudinal beam; 6, original bridge transverse beam; 7, hanger; 8, bridge deck system. DETAILED DESCRIPTION

[0034] The present application will be further described in detail below with reference to the accompanying drawings, so that those skilled in the art can implement it according to the description.

[0035] It should be noted that the experimental methods in the following embodiments are conventional methods, and the reagents and materials are commercially available unless otherwise specified. In the description of the present application, the terms "transverse", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0036] As shown in Figures 1-4 The present application provides a construction method for transforming a suspender arch bridge by using a steel truss beam, comprising:

[0037] S1, constructing a plurality of pile foundations along the length direction of the bridge, and installing corresponding pile caps and lower pier column segments on the pile foundations;

[0038] S2, installing a combined support corresponding to the upper side of the lower pier column segment, and fixing the bottom of the combined support on the side wall of the lower pier column segment;

[0039] S3, installing a lower truss beam segment on the combined support outside the bridge projection surface and connecting two lower truss beam segments along the length direction of the bridge to form a whole, i.e. completing the installation of the lower truss beam;

[0040] S4, pushing the lower truss beam laterally on the combined support to the designed position;

[0041] Wherein, the lower truss beam is pushed to the position directly below the predetermined installation position (i.e. the designed position) along the support plane of the combined support outside the bridge projection surface, and the designed position is the position of the steel truss beam to be installed in the width direction of the bridge, i.e. the lateral designed position;

[0042] S5, lifting the lower truss beam vertically on the combined support to abut the bottom of the original bridge beam, and the lower truss beam reaches the longitudinal designed position after being pushed to abut the bottom surface of the original bridge beam, at which time the lower truss beam is in the predetermined installation position, and the lower truss beam and the original bridge beam can be preliminarily connected by temporary fixation to ensure that the lower truss beam can be stably maintained in the designed state;

[0043] S6, installing an upper truss beam segment on the top of the original bridge beam, which corresponds to the lower truss beam segment, and connecting the upper truss beam segment and the lower truss beam segment to form a whole, i.e. completing the assembly of the steel truss beam;

[0044] Wherein, the corresponding upper truss segment and lower truss segment can be connected as a whole by means of bolting, riveting, cementing or welding, etc. The upper truss segment is assembled downward from the bridge deck. Before connection, the part of the bridge deck system interfering with the upper and lower truss segments (i.e. the part of the bridge deck panel directly above the original bridge beam) needs to be removed, so that the upper truss segment can be connected with the corresponding lower truss segment smoothly through the bridge deck. Here, the steel truss is divided into multiple steel truss segments, which correspond to all original bridge beams one by one. Any steel truss segment is composed of the corresponding upper truss segment and lower truss segment connected and is a hollow structure, which is sleeved outside the corresponding end of the original bridge beam and matches the cross-sectional shape thereof. The upper truss segment and lower truss segment after connection press the end of the original bridge beam inward and are connected as a whole, which facilitates the synchronous jacking of the original bridge beam and the steel truss in the subsequent system conversion construction, and realizes the unloading of the cable force of the suspender.

[0045] S7, the upper pier column segment and the bent cap corresponding to the top end of the lower pier column segment are constructed;

[0046] S8, the steel truss is lifted as a whole, the beam is dropped after the system conversion is completed, and then the combined support is removed, i.e. the reconstruction of the suspender arch bridge is completed.

[0047] In the technical solution, the original suspender arch bridge is supported by the newly added steel truss and the lower structure, the original suspender arch bridge includes an original bridge cross beam, an original bridge longitudinal beam, an original bridge arch rib and a suspender, the original bridge cross beam and the original bridge longitudinal beam are supported under the bridge deck system in a longitudinal and horizontal beam staggered structure, the original bridge arch rib is arranged on both sides of the bridge deck (above the original bridge longitudinal beam) and is anchored at the end of the original bridge cross beam through the staggered suspender. In this embodiment, the modified suspender arch bridge has two newly added structures: a steel truss and a lower structure, wherein the newly added steel truss includes two steel trusses, which are arranged at intervals on both sides of the bridge deck and are located inside the original bridge longitudinal beam, the original bridge arch rib and the suspender, any steel truss is arranged along the length of the bridge and includes a plurality of steel truss segments, and the original bridge cross beam passes through the internal gap of the steel truss segment on both sides of the bridge deck and is integrated with the steel truss segment; the lower structure is arranged in the soil layer under the bridge, and any complete lower structure includes a pile foundation, a pile cap, a lower pier column segment, an upper pier column segment and a bent cap which are arranged continuously in the vertical direction, the lower structure is arranged to support the newly added steel truss, the number of the newly added lower structure is determined according to the original bridge parameters and the newly designed beam bridge structure, in order to match the number of the steel truss, all the lower structures are divided into two groups and arranged on both sides under the bridge, any group of lower structures includes a plurality of lower structures arranged at intervals along the length of the bridge. The construction of the newly added lower structure is carried out according to the construction requirements and steps of the newly built bridge, but due to the existence of the bridge deck system, the operation space for the installation and construction of the lower structure under the bridge is limited, in order to avoid affecting the bridge deck system structure and reducing the impact on the normal traffic operation of the bridge, the construction equipment with small clearance requirements should be used as much as possible for the construction of each part of the lower structure. Specifically, the overall lower structure construction is mainly divided into two parts according to the installation progress of the steel truss, the installation of the pile foundation, the pile cap and the lower pier column segment is carried out in S1 (before the installation of the steel truss), and sufficient space is reserved above the lower pier column segment to facilitate the construction of the steel truss, that is, the design height of the upper pier column segment is greater than or equal to the design height of the lower pier column segment; the installation of the upper pier column segment and the bent cap is carried out in S7 (after the assembly of the steel truss is completed), so that the steel truss does not interfere with the upper pier column segment during the construction process, and the later constructed upper pier column segment is convenient to adjust according to the actual installation height of the steel truss. In S7, the installed upper pier column segment and the bent cap are sleeved in the combined support, that is, the upper pier column segment and the bent cap are used for in-situ heightening of the lower pier column segment, at this time the steel truss structure has been assembled, and the top surface of the bent cap is arranged as close as possible to the bottom surface of the steel truss during installation; in S8, the system conversion converts the bridge from the load system of the suspender arch bridge to the load system of the beam bridge (lower structure-steel truss-bridge deck system), after the system conversion is completed, the jacking force applied by the steel truss is removed, and the steel truss and the original bridge cross beam (and other original bridge structures) can be naturally supported on the complete lower structure (bent cap) to realize the beam falling.The combined support jacket is outside the lower pier column segment, can provide a temporary support platform for the transverse and longitudinal positioning and installation of the steel truss beam without interfering with the lower structure (pier column structure), the support platform provided by the combined support jacket is below the original bridge beam and can extend to the outside of the bridge projection surface, facilitating the smooth hoisting of multiple lower truss beam segments onto the combined support jacket. The combined support jacket is also provided with a jacking and jacking device and a control system, which can position and install the lower truss beam through transverse jacking and longitudinal jacking, wherein the jacking device can be selected from horizontal electric push rods, hydraulic cylinders, etc., the jacking device can be selected from jacks, and the control system is electrically connected with the jacking and jacking device to control the movement and positioning of the lower truss beam according to the design parameters, and the installation position of the lower truss beam can also be adjusted in real time according to the actual construction condition by inputting control instructions by the worker. Thus, the initial hoisting position of the lower truss beam segment can have a certain deviation, and then the lower truss beam segment is gradually positioned and installed to the accurate design position through transverse jacking and longitudinal jacking, thereby reducing the requirements for hoisting equipment and hoisting precision.

[0048] The construction method has good controllability, effectively improves the construction stability and safety, and ensures the quality of the reconstructed bridge, and can be widely applied to the reconstruction construction of various different structures and forms of suspender arch bridges. The reconstructed steel truss beam system and the longitudinal and transverse beam stiffened beam system of the original suspender arch bridge jointly support the bridge deck system, which has good reinforcing effect without changing the original bridge foundation structure, maximally reduces the influence of the reconstruction construction on the traffic operation of the original bridge, greatly reduces the stress of the original bridge suspender after the reconstruction is completed, reduces the possibility of safety accidents caused by factors such as aging of the original bridge suspender system, and is beneficial to prolonging the service life of the old bridge and ensuring the use safety.

[0049] In another technical scheme, the construction method for reconstructing a suspender arch bridge by using a steel truss beam, in S2, the combined support includes a three-dimensional frame, which is a hollow structure sleeved on the outer wall of the lower pier column segment and extends upward along the height direction thereof; two support beams are fixed on the top of the three-dimensional frame on both sides, and any support beam is horizontally arranged along the width direction of the bridge and extends from the outside of the bridge projection surface to the inside of the bridge projection surface, and a track is arranged on the support beam along the length direction, and the lower truss beam segment is installed on the track and is in sliding connection with the track; a jacking device is arranged on the track and is used to drive the lower truss beam to move on the support beam; a jacking device is arranged on the support beam and is located at the designed position of the lower truss beam, and the jacking device is used to control the height position of the lower truss beam.

[0050] The top elevation of the combined support is not lower than the top elevation of the lower pier column segment, a part of the support beam is located in the bridge projection plane, and another part is located outside the bridge projection plane, so that there is enough installation space for the lower truss and a support platform within a certain range inside and outside the bridge projection plane (below), which is beneficial to realize the horizontal jacking and longitudinal jacking of the steel truss on the combined support. Specifically, the support beam is arranged on both sides of the top of the three-dimensional frame through the distribution beam. In order to adapt to the length range of the support beam and provide reliable support for it, the three-dimensional frame has a certain width (length along the width direction of the bridge). When installing the distribution beam, attention should be paid to avoiding the installation range of the lower structure (upper pier column segment). The two support beams are arranged on both sides of the top of the three-dimensional frame along the length direction of the bridge, and attention should also be paid to avoiding the installation range of the upper pier column segment to avoid interference. The jacking device is used to drive the lower truss to move on the support beam, and the jacking device is used to drive the lower truss to move in the height direction. In this embodiment, the jacking device includes a horizontally arranged first jack (not shown in the figure), which is arranged at the end of the track. Two sliders are arranged on the track at intervals, and a mounting seat is fixedly arranged on the top of the sliders. The lower truss segment is mounted on the mounting seat. The jacking end of the first jack is fixedly connected with the outer end of the adjacent slider, so that the horizontal movement of the slider, the mounting seat and the lower truss segment on the track (support beam) can be realized by the jacking end of the first jack. The jacking device includes a vertically arranged second jack, which is arranged at the designed position where the lower truss segment is to be jacked to the position in S4 and does not interfere with the jacking device. The jacking end of the second jack in the initial state is lower than the bottom surface of the lower truss segment, so that when the lower truss segment is jacked to the position by the jacking device in S4, it is located directly above the jacking device. At this time, the lower truss segment can be jacked upward from the mounting seat by the movement of the jacking end of the jacking device, realizing the control of the height position of the lower truss, and the mounting seat does not interfere with the change of the height of the lower truss segment.

[0051] The combined support must ensure sufficient rigidity, strength, stability and anti-overturning ability to ensure the stability in the construction of the steel truss beam. The elevation of the top surface of the support should be strictly controlled during the construction of the combined support to ensure that the lower truss segments can be smoothly connected after the initial hoisting and installation of the lower truss segments on the support beam. In S3, the position of the single lower truss segment can be adjusted by the jacking device when the adjacent lower truss segments are spliced to smoothly complete the connection of the overall lower truss. Since the lower truss segments are connected as an overall lower truss in S3, the jacking devices on different combined supports simultaneously jack the corresponding lower truss segments to the designed position in S4 during the construction of the same steel truss beam. The jacking devices on different combined supports simultaneously jack the corresponding lower truss segments to the designed position in S5. Specifically, the method for jacking the lower truss segments using the jacking device in S5 includes:

[0052] S51, trial jacking: before the formal jacking, the jacking system is debugged, the jacks are pressurized in stages according to the theoretical weight, the stability of the combined support and the influence of the deformation of the support body on the jacking process are closely monitored during the trial jacking, the working condition of the limit position in the jacking process is checked, the reaction data of the monitoring system are compared with the actual situation, and the monitoring system is optimized accordingly; after the trial jacking is completed, the overall attitude, structural displacement and other conditions are provided to provide a basis for the formal jacking;

[0053] S52, after the trial jacking, if there is no problem, the jacking device is used to formally jack the lower truss segments;

[0054] S53, the actual jacking situation is monitored synchronously by the monitoring system during the jacking process, and the jacking is stopped in time and handled when problems occur;

[0055] S54, after jacking to the designed position, the overall lower truss is temporarily supported or fixed to maintain the designed state.

[0056] In another technical solution, the construction method for transforming the suspender arch bridge by using the steel truss beam further comprises a limiting device arranged at the end of the support beam located in the bridge projection plane, and the limiting device is used to limit the transverse displacement of the lower truss segment on the track. Specifically, the limiting device can be selected from structures such as a limiting plate or a limiting block, which is relatively fixed at a set position at the end of the support beam. When the lower truss segment is jacked to abut against the limiting device (i.e., when the jacking device drives the sliding block to abut against the limiting device), the jacking is stopped. The lower truss segment can be moved to the designed position in S4, i.e., directly above the jacking device, which facilitates the control of the displacement of the lower truss segment and effectively avoids the excessive displacement (over-jacking) of the lower truss segment on the support beam, thereby ensuring the smooth construction.

[0057] In another technical solution, in the construction method for transforming the suspender arch bridge by using the steel truss beam, in S2-S3, the number of the combined supports is greater than or equal to the number of the lower pier column segments, the combined supports correspond to the suspender anchors one by one and are arranged directly below the suspender anchors; the combined supports are divided into direct supports and indirect supports according to the connection mode, the direct supports correspond to the lower pier column segments one by one and are fixedly connected, and the indirect supports are arranged between two adjacent direct supports and are integrated with the adjacent direct supports through the corresponding lower truss beam segments. In the above technical solution, the number of the combined supports corresponds to the number of the suspender anchors, and when the pile foundation is constructed in S1, the number of the lower structures can be less than the number of the combined supports, that is, the number of the lower structures does not need to be constructed according to the number of the combined supports. In S2, a plurality of combined supports (direct supports) corresponding to the lower structures are installed and fixedly connected to the lower pier column segments; and the remaining combined supports (indirect supports) are preliminarily positioned through a floating crane or the like and arranged between the direct supports according to the designed positions. In S3, when the lower truss beam segments are installed on the combined supports and connected two by two, the direct supports and the indirect supports can be indirectly integrated into a whole through the lower truss beam segments fixedly connected to each other, wherein the corresponding lower truss beam segments and the combined supports (direct supports or indirect supports) are relatively fixed during installation and will not move relatively under the condition that no external force (jacking or jacking up) is applied, and in the subsequent jacking and jacking up operations, the power devices on the indirect supports and the direct supports keep synchronous action, which will not affect the installation of the whole steel truss beam and the system conversion construction. Thus, the amount of materials is reduced as much as possible under the condition of ensuring the transformation effect, unnecessary temporary support loss is reduced during the installation of the steel truss beam, the construction efficiency is improved, and the construction cost is reduced.

[0058] In another technical solution, in the construction method for transforming the suspender arch bridge by using the steel truss beam, in S4, the designed positions are located at the inner sides of the original bridge arch ribs and the original bridge longitudinal beams. That is, the relative installation positions of the steel truss beams on the original bridge structure are located at the inner sides of the original bridge arch ribs, the original bridge longitudinal beams and the suspender, and the two steel truss beams are symmetrically arranged at the two sides of the bridge deck. Thus, the separated steel truss beam segments (lower truss beam segments + upper truss beam segments) are conveniently and stably connected to the original bridge cross beams, the original bridge arch ribs, the longitudinal beams and the suspender are not changed or affected, the safety of the transformation construction and the relative stability of the original bridge structure are ensured; meanwhile, the steel truss beam segments are fixedly sleeved with the end heads of the original bridge cross beams, the stability of the connection between the steel truss beam and the original bridge cross beam in the system conversion is ensured, and the construction safety is further ensured.

[0059] In another technical solution, in the method for reconstructing a suspender arch bridge by using a steel truss beam, the lower truss beam segment and the upper truss beam segment are sequentially installed along a direction from a bridge side span to a bridge midspan. In the above technical solution, the segment beam (upper truss beam segment / lower truss beam segment) is hoisted from the two ends of the bridge to the middle of the bridge during the installation of the steel truss beam, which is beneficial to guarantee the overall stability of the bridge during the construction and improve the construction efficiency.

[0060] In another technical solution, in the method for reconstructing a suspender arch bridge by using a steel truss beam, the upper pier column segment and the lower pier column segment are pier column structures that are continuously arranged along a vertical direction, and the upper pier column segment is connected with the lower pier column segment through a connecting key. Specifically, during the construction of the pile foundation, the pile cap and the lower pier column segment in S1, the connecting key is reserved at the top of the lower pier column segment, so that the installation of the upper pier column segment on the lower pier column segment can be directly performed after the installation of the steel truss beam is completed (after the construction in S6 is completed), and the upper pier column segment and the cap beam can be integrally prefabricated or cast in situ and connected with the lower pier column segment through the reserved connecting key, which is beneficial to speed up the construction progress and guarantee the construction quality.

[0061] In another technical solution, in the method for reconstructing a suspender arch bridge by using a steel truss beam, the step of system transformation in S8 comprises:

[0062] S81, the steel truss beam is integrally jacked up to unload the suspender cable force, here, a new jack can be installed on the lower structure (upper pier column segment), or the original jacking device on the combined support can be directly used to synchronously jack up the whole steel truss beam (second jacking), and the jacking is stopped after each jacking point reaches the system transformation requirement;

[0063] S82, a support is installed between the cap beam and the jacked steel truss beam; wherein the support is installed on the top of the cap beam after the steel truss beam is jacked up in place, the limiting groove at the top of the support matches the cross section of the steel truss beam, and the bottom surface elevation of the limiting groove is close to or equal to the bottom surface elevation of the steel truss beam;

[0064] S83, the jacking force on the steel truss beam is gradually reduced to drop the beam until the steel truss beam is completely supported on the support, i.e., the system transformation is completed; during the beam dropping, the jacking end of the jacking device (second jack) is gradually reset (descends), so that the steel truss beam and the original bridge beam are synchronously dropped on the support of the lower structure (cap beam), and in the above process, when the bottom surface elevation of the limiting groove of the installed support is equal to the bottom surface elevation of the steel truss beam, the height of the steel truss beam and the original bridge beam hardly changes, only the stress point of the support changes from the jacking device to the newly added lower structure, which further guarantees the stability of the whole system transformation process.

[0065] In the above technical scheme, the bridge needs to be closed for traffic during the system conversion construction, and a monitoring system is used to implement third-party monitoring to ensure the safety and system stability during the system conversion. After the system conversion construction is completed, the jacking device on the combined support is removed (the jack is taken out), and then other structures of the combined support are sequentially dismantled, that is, the construction of transforming the boom arch bridge into a beam bridge by using a steel truss beam is completed.

[0066] Although the embodiments of the present application have been disclosed as above, they are not limited to the application listed in the specification and the embodiments, and can be fully applied to various fields suitable for the present application, and other modifications can be easily implemented by those skilled in the art, and therefore the present application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A construction method for converting a steel truss girder into a suspension arch bridge, characterized in that, include: S1. Construct multiple pile foundations along the length of the bridge, and install corresponding pile caps and lower pier column segments on the pile foundations; S2. Install a combined bracket above the lower pier segment, with its bottom fixedly sleeved on the side wall of the lower pier segment. S3. Install the lower truss segments on the combined support outside the bridge projection plane and connect them in pairs along the length of the bridge to form a whole, thus completing the installation of the lower truss. S4. Push the lower truss beam laterally on the combined support to the designed position, which is located inside the original bridge arch rib and the original bridge longitudinal beam. S5. Longitudinally lift the lower truss beam on the combined support until it abuts against the bottom of the original bridge crossbeam; S6. Install the upper truss segment on the top of the original bridge crossbeam, which corresponds one-to-one with the lower truss segment. Connect the upper truss segment and the lower truss segment to form a whole, thus completing the assembly of the steel truss. S7. Construct the upper pier segment and cap beam corresponding to the top of the lower pier segment; S8. Lift the steel truss as a whole, lower the beam after completing the system conversion, and then dismantle the combined support to complete the transformation of the suspension arch bridge. The steel truss is divided into multiple steel truss segments, which correspond one-to-one with all the original bridge crossbeams. Each steel truss segment consists of a corresponding upper truss segment and a lower truss segment and is a hollow structure. It is fitted onto the outer side of the corresponding original bridge crossbeam end and matches its cross-sectional shape.

2. The construction method for modifying a suspension arch bridge using steel truss beams as described in claim 1, characterized in that, In S2, the combined support includes a three-dimensional frame, which is a hollow structure fitted onto the outer wall of the lower pier segment and extending upward along its height direction; two support beams, which are fixed to the top two sides of the three-dimensional frame, with one support beam horizontally arranged along the width direction of the bridge and extending from outside the bridge projection plane to inside the bridge projection plane, and a track provided along the length direction on the support beam, with the lower truss segment installed on the track and slidably connected to it; a jacking device, which is arranged on the track and used to drive the lower truss to move on the support beam; and a lifting device, which is arranged on the support beam and located at the designed jacking position of the lower truss, and the lifting device is used to control the height position of the lower truss.

3. The construction method for modifying a suspension arch bridge using steel truss beams as described in claim 2, characterized in that, The combined support also includes a limiting device, which is disposed at the end of the support beam located within the bridge projection plane. The limiting device is used to limit the lateral displacement of the lower truss segment on the track.

4. The construction method for modifying a suspension arch bridge using steel truss beams as described in claim 1, characterized in that, In S2-S3, the number of the combined supports is greater than or equal to the number of the lower pier column segments. The combined supports correspond one-to-one with the anchor heads of the suspenders and are set directly below them. The combined supports are divided into direct supports and indirect supports according to the connection method. The direct supports correspond one-to-one with the lower pier column segments and are fixedly connected. The indirect supports are set between two adjacent direct supports and are connected to the adjacent direct supports through the corresponding lower truss segments.

5. The construction method for modifying a suspension arch bridge using steel truss beams as described in claim 1, characterized in that, In S3 and S6, the lower truss segment and the upper truss segment are installed sequentially along the direction from the side span of the bridge to the middle span of the bridge.

6. The construction method for modifying a suspension arch bridge using steel truss beams as described in claim 1, characterized in that, In S7, the upper pier segment and the lower pier segment are pier structures that are continuously arranged in the vertical direction, and the upper pier segment is connected to the lower pier segment by a connecting key.

7. The construction method for modifying a suspension arch bridge using steel truss beams as described in claim 1, characterized in that, In S8, the system conversion steps include: S81. Lift the steel truss girder as a whole until the cable tension of the suspenders is unloaded; S82. Install supports between the cap beam and the lifted steel truss beam; S83. Gradually reduce the lifting force on the steel truss beam to lower it until the steel truss beam is fully supported on the support, thus completing the system conversion.

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