A construction method for system conversion of a half-through arch-beam cooperative steel box continuous arch bridge based on the stability of the bare arch

Abstract

The present invention belongs to the construction method of a steel arch bridge with a collaborative system of a middle-supported arch and beam, and particularly relates to a system conversion construction method for a middle-supported arch-beam collaborative steel box continuous arch bridge based on the stability of the bare arch. The overall method adopts the construction method of beam first and then arch. However, by optimizing the removal sequence of the arch rib supports, the present invention can remove some of the middle-span arch rib supports in advance after the middle arch is closed, which can advance the start time of the arch rib decorative plate process and the hanger installation process, forming a flow operation of the main beams of the middle span, secondary side spans, and side spans, arch rib installation, arch rib support removal, decorative plate installation, and hanger installation, greatly saving the construction period. In addition, the removed middle-span arch rib supports can be recycled for use in the side arches, which not only reduces the occupation of the construction site, but also reduces the one-time investment cost of the support materials, saving costs.

Description

Technical Field

[0001] The present invention belongs to the construction method of a steel arch bridge with a collaborative system of a middle-supported arch and beam, and particularly relates to a system conversion construction method for a middle-supported arch-beam collaborative steel box continuous arch bridge based on the stability of a bare arch. Background Art

[0002] In the design of municipal bridges, a tied-arch bridge is an arch-beam composite system bridge that combines the advantages of an arch and a beam. It combines two basic structures, an arch and a beam, to jointly bear the load, giving full play to the structural performance and combined action of the beam in bending and the arch in compression. The composite system generally adopts the installation method of "beam first and then arch" or "arch first and then beam". Finally, a part of the force of the beam is transmitted to the arch through the suspenders, forming a composite system in which the arch and the beam jointly bear the force. In the design scheme, the conversion of the arch-beam composite system is divided into two stages. In the first stage, all main beams and arch ribs are first constructed. After the installation, welding, and inspection of all arch beams are completed, the arch rib supports are successively removed, and the external decorative plates and suspenders of the arch ribs are installed synchronously. In the second stage, after the suspenders are successively symmetrically tensioned in stages, the main beam supports are removed, and the bearings are unlocked, and the system conversion is completed. However, the arch-beam composite system bridge has the following disadvantages: the structural force is complex. Before the system is formed, the individual structure is weak in resisting the influence of external conditions, and the safety risk is relatively large. Especially for a multi-span continuous arch bridge, the process of system conversion is relatively complex, and the construction period is often relatively long. Summary of the Invention

[0003] The purpose of the present invention is to provide a system conversion construction method for a middle-supported arch-beam collaborative steel box continuous arch bridge based on the stability of a bare arch.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0005] A system conversion construction method for a middle-supported arch-beam collaborative steel box continuous arch bridge based on the stability of a bare arch, the steps are as follows:

[0006] 1) First, install the main beam supports of the middle span and the main beam supports of the secondary side spans and conduct acceptance. Then, symmetrically install the main beam of the middle span, the arch rib supports of the middle span, and the arch rib of the middle span. After that, symmetrically install the main beam of the secondary side spans; or symmetrically install the main beam of the middle span, the main beam of the secondary side spans, the arch rib supports of the middle span, and the arch rib of the middle span after the acceptance of the main beam supports;

[0007] 2) After the main beam of the middle span, the arch rib of the middle span, and the main beam of the secondary side spans are all installed, welded, and inspected qualified, the supports of the arch rib of the middle span are removed in a skip manner. For the arch rib of the middle span with the removed supports, install the suspenders correspondingly, and the suspenders are synchronously symmetrically tensioned to 10-15% of the initial stress;

[0008] 3) Install the arch rib supports of the secondary side spans, and then symmetrically install the arch ribs of the secondary side spans; remove the remaining supports of the arch rib of the middle span and install the suspenders correspondingly, and the suspenders are synchronously symmetrically tensioned to 10-15% of the initial stress;

[0009] 4) When there is a side span in the continuous arch bridge, install the side span main girder, weld it, and pass the inspection. Moreover, the installation steps of the side span main girder can be advanced to be carried out together with the secondary side span arch rib support in step 3); install the side span arch rib support and the side span arch rib in sequence, and then remove the secondary side span and side span arch rib supports and install the suspenders, and adjust the tension of the suspenders to 10-15% of the initial stress.

[0010] 5) Tension the suspenders symmetrically and step by step to the design stress value, remove the main girder support, unlock the bearing, and complete the system transformation.

[0011] Among them, in step 1), the less support method can be adopted, and the mid-span main girder and arch rib are symmetrically installed in sequence by using a crawler hoisting device, and the secondary side span main girder is symmetrically installed.

[0012] In step 2), the so-called skip demolition needs to meet the requirement that the remaining supports can support the arch rib and install the suspenders.

[0013] Preferably, the supports removed by skip demolition can be used for the subsequent erection of the continuous arch rib supports.

[0014] In steps 2), 3), and 4), it is preferably to adjust the tension of the suspenders to 10% of the initial stress.

[0015] The present invention is applicable to both equal-span continuous arch bridges and unequal-span half-through arch-beam cooperative steel box continuous arch bridges. In addition, in the current municipal engineering field, the maximum number of steel structure bridges with 5 arches. Therefore, the present invention only exemplarily describes the system transformation method of the half-through arch-beam cooperative steel box continuous arch bridge with a mid-span, a secondary side span, and a side span. In fact, if it is applied to continuous arch bridges with more continuous arches, there is no problem either. The main thing that needs to be adjusted is only the repetition of the skip demolition part of the arch rib support. As long as it is based on the force condition of the continuous arch bridge, when the span of the continuous arch is large, in order to avoid occupying too many supports and reusing the supports while also reducing the consumption of materials and the floor area, the number of continuous arches to be skip-demolished is correspondingly increased. At the same time, according to the mechanical calculation, the specific number of supports to be skip-demolished and the specific supports can be determined.

[0016] Taking the installation of the mid-span arch rib of the present invention divided into 9 segments as an example, 10 segments of supports can be set, and when skip-demolishing, the 1st, 2nd, 5th, 6th, 9th, and 10th groups of supports of the mid-span arch rib are skip-demolished; finally, the 3rd, 4th, 7th, and 8th groups of supports are removed.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] A construction method for system conversion of a half-through arch-beam cooperative steel box continuous arch bridge based on the stability of the bare arch. The existing system conversion plan is the construction process of beam first and then arch. The main beam is installed in sequence of the middle span, secondary side span, and side span. After the installation and acceptance of the middle span main beam, the arch rib support and arch rib segments of the middle span are installed. The arch rib segments of the secondary side span and side span are installed synchronously and symmetrically in the same process as the middle span. After the installation and acceptance of all seven beams and five arches of the whole bridge, the arch rib supports of the middle span, secondary side span, and side span are symmetrically removed in sequence, the upper and lower exterior panels are installed, the suspenders are installed, and tensioned to the design control stress in stages, and the main beam support is removed and the bearing is unlocked to complete the conversion of the force system. In the system conversion construction method of the present invention, by optimizing the removal sequence of the arch rib support, part of the arch rib support of the middle span is removed in advance after the closure of the middle arch, which can advance the start time of the arch rib decorative panel process and the suspender installation process, greatly saving the construction period. For the situation where the construction period is tight and the system conversion needs to be completed as soon as possible, the present invention can not only complete the system conversion faster than the existing method, but also ensure the required cross-sectional area for river flood discharge and ensure the safety of the bridge structure under the influence of flood during the flood season. In addition, the removed arch rib support of the middle span can be recycled and used for the side arch, which not only reduces the occupation of the construction site, but also reduces the one-time investment cost of the support materials and saves costs. Description of the Drawings

[0019] Figure 1 It is a three-dimensional modeling diagram of the bridge;

[0020] Figure 2 It is a schematic diagram of the arch rib decomposition of the embodiment of the present invention;

[0021] Figure 3 It is a schematic diagram of the assembled arch rib structure;

[0022] Figure 4 It is a diagram of the arch rib segment division (half-span schematic);

[0023] Figure 5 It is a schematic diagram of the middle span arch rib support setting;

[0024] Figure 6 It is a schematic diagram of the middle span main beam installation;

[0025] Figure 7 It is a schematic diagram of the middle span arch rib support installation;

[0026] Figure 8 It is a schematic diagram of the middle span arch rib installation and synchronous installation of the secondary side span main beam;

[0027] Figure 9 It is a schematic diagram of the middle span skipping and removing part of the middle span arch rib support, installing the corresponding suspenders, and installing the side span main beam and secondary side span arch rib support;

[0028] Figure 10 It is a schematic diagram of the first-stage removal of the middle span arch rib support;

[0029] Figure 11 Schematic diagram of the side span arch rib installation, the remaining supports of the middle span arch rib symmetrically removed and the hangers installed synchronously, and the side span arch rib supports installed;

[0030] Figure 12 It is a schematic diagram of the secondary side span arch rib support being symmetrically and synchronously removed and the hangers being installed, and the side span arch rib being installed;

[0031] Figure 13 This is a schematic diagram of the symmetrical and synchronous removal of the side span arch rib supports and the installation of the hangers;

[0032] Figure 14 This is a schematic diagram after the main beam support is removed, the bearings are unlocked, and the system conversion is completed. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is described below with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0034] A certain bridge is located downstream of the flood discharge channel of a reservoir and a dam. During the flood season, construction is greatly affected by the flood discharge from upstream. Structural safety is the primary consideration in bridge construction. Combined with the flood conditions in previous years, construction of the main structure of the bridge is concentrated in the non-flood season. It is necessary to complete the conversion of the force system of the entire bridge before the flood season and dismantle the main beam support to ensure normal flood discharge in the river and the safety of the bridge structure. The effective construction period is very tight, and it is crucial to quickly complete the conversion of the force system.

[0035] The bridge is a seven-beam five-arch mid-support unequal-span arch-beam cooperative system. The arch piers are consolidated at the middle arch foot, the arch beams are separated, and supports are set at the bottom of the beams; the arch beams are consolidated at the side arch feet, and movable supports are set at the bottom of the beams and arches. The arch rib section adopts the structural form of "quadrilateral core tube + special-shaped exterior panels". The arch rib cross bridge is inclined outward by 10°. A hanger is set every 7m, and there are 86 hangers in the whole bridge. The installation method of beam first and arch later is adopted, and the bracket method is used for in-situ lifting. The conversion of the bridge force system is the top priority of the whole bridge, which is directly related to the structural force, line shape and safety after the bridge is completed. The original design system conversion plan is to install the arch rib core tube first, remove the arch rib bracket after the welding inspection of each segment, install the upper and lower exterior panels, and then install the hanger, tension to the design value in stages, remove the main beam bracket, unlock the support, and complete the conversion of the force system. Since the cofferdam in the river channel was constructed using the in-situ scaffolding method and was affected by the flood flow in the river during the flood season, the effective construction time of the bridge was urgent and the system conversion needed to be completed quickly.

[0036] In order to meet the requirements of the construction period and quickly complete the conversion of the force system, the present invention is used for construction, and the specific steps are as follows:

[0037] (1) Overall 3D modeling of the bridge. For details, see the attached Figure 1; Among them, the overall outline of the cross-arch rib section is an irregularly gradually changing hexagon, adopting the structural form of "quadrilateral core tube + special-shaped exterior panel", see the appendix for details Figure 2 and Figure 3 ;

[0038] (2) Fabricate the side-span arch ribs. The side-span arch ribs are fabricated in 5 segments, the secondary side-span arch ribs are fabricated in 7 segments, and the middle-span arch ribs are fabricated in 9 segments. See the appendix for details Figure 4 ;

[0039] (3) The middle-span arch ribs are divided into 9 installation segments, connected to the extended sections of the arch feet at both ends, and 10 groups of brackets are set below. See the setting diagram in the appendix Figure 5 , where ①, ②, ③, ④, ⑤, ⑥, ⑦, ⑧, ⑨, ⑩ respectively correspond to the 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 9th, and 10th groups of brackets, and the same meaning applies in other attached drawings;

[0040] (4) The system conversion process is as follows (the processes of installing and accepting the main beam brackets and other processes involving welding and inspection are not elaborated here):

[0041] A) Install the middle-span main beam (see the appendix Figure 6 );

[0042] B) Install the middle-span arch rib brackets (see the appendix Figure 7 );

[0043] C) Install the middle-span arch ribs and synchronously install the secondary side-span main beam (see the appendix Figure 8 );

[0044] D) Jump-remove the 1st, 2nd, 5th, 6th, 9th, and 10th groups of brackets of the middle-span arch ribs and synchronously install the corresponding suspenders, and the suspenders are synchronously symmetrically tensioned to 10% of the initial stress. Install the side-span main beam and the secondary side-span arch rib brackets (see the appendix Figure 9 and Figure 10 );

[0045] E) After the secondary side-span arch ribs are installed, symmetrically remove the remaining 3rd, 4th, 7th, and 8th groups of brackets of the middle-span arch ribs and synchronously install the suspenders, and the suspenders are synchronously symmetrically tensioned to 10 of the initial stress; then install the side-span arch rib brackets. See the appendix Figure 11 ;

[0046] F) Install the side-span arch ribs, symmetrically and synchronously remove the secondary side-span arch rib brackets and install and tension the suspenders to 10% of the initial stress. See the appendix Figure 12 ;

[0047] G) Symmetrically and synchronously remove the side-span arch rib brackets and install and tension the suspenders to 10% of the initial stress. See the appendix Figure 13 ;

[0048] H) The hanger rods are symmetrically tensioned in stages to the design stress value, the main beam supports are removed, the bearings are unlocked, and the system conversion is completed. See the appendix for details. Figure 14 .

[0049] Using the above system conversion construction method of the present invention from the installation of the main beam to the completion of the system conversion, the construction period is only 182 days. No safety or quality accidents occurred during the construction period. The construction progress met the planned requirements, and the project was completed and opened to traffic 6 months ahead of schedule.

Claims

1. A system conversion construction method for a mid-through arch-beam cooperative steel box double-arch bridge based on bare arch stability, characterized in that: The steps are as follows: 1) First, install the middle-span main girder supports and the secondary side-span main girder supports and conduct acceptance. Then, symmetrically install the middle-span main girder, the middle-span arch rib supports, and the middle-span arch rib. After that, symmetrically install the secondary side-span main girder or symmetrically install the middle-span main girder, the secondary side-span main girder, the middle-span arch rib supports, and the middle-span arch rib; 2) After the middle-span main girder, the middle-span arch rib, and the secondary side-span main girder are all installed, welded, and inspected qualified, perform skip demolition on the supports of the middle-span arch rib. Install the suspenders corresponding to the middle-span arch rib with the supports skipped, and synchronously and symmetrically tension the suspenders to 10 - 15% of the initial stress. The middle-span arch rib is installed in 9 segments, with 10 sets of supports. When performing skip demolition, skip demolish the 1st, 2nd, 5th, 6th, 9th, and 10th sets of supports of the middle-span arch rib. The last sets of supports to be demolished are the 3rd, 4th, 7th, and 8th sets; 3) Install the secondary side-span arch rib supports, and then symmetrically install the secondary side-span arch rib. Demolish the remaining supports of the middle-span arch rib and install the corresponding suspenders, and synchronously and symmetrically tension the suspenders to 10 - 15% of the initial stress; 4) When there are side spans in the continuous arch bridge, install the side-span main girder, weld it, and inspect it qualified. The installation steps of the side-span main girder can be advanced to be carried out together with the secondary side-span arch rib supports in step 3). Install the side-span arch rib supports and the side-span arch rib in sequence. Then, carry out the demolition of the secondary side-span and side-span arch rib supports and the installation of the suspenders, and adjust the tension of the suspenders to 10 - 15% of the initial stress; 5) Symmetrically and gradually tension the suspenders to the design stress value, demolish the main girder supports, unlock the bearings, and complete the system conversion.

2. The system conversion construction method of the mid-through arch-beam cooperative steel box double-arch bridge based on bare arch stability as claimed in claim 1 is characterized in that: The skip demolition mentioned above needs to meet the requirement that the remaining supports can support the arch rib and the suspenders can be installed.

3. The system conversion construction method of the half-through arch-beam cooperative steel box continuous arch bridge based on the stability of the bare arch as claimed in claim 2, characterized in that, The supports demolished by skip demolition can be used for the subsequent erection of the continuous arch rib supports.

4. The system conversion construction method of the half-through arch-beam cooperative steel box continuous arch bridge based on the stability of the bare arch as described in any one of claims 1-3, characterized in that, The above-mentioned mid - supported arch - girder cooperative steel box continuous arch bridge is an unequal - span continuous arch bridge.

5. The system conversion construction method of the half-through arch-beam cooperative steel box continuous arch bridge based on the stability of the bare arch as claimed in claim 4, characterized in that In steps 2), 3), and 4), adjust the tension of the suspenders to 10% of the initial stress.

Images