Installation method for long-span floor arch structure with arch-foot prestressed balance cables

Abstract

An installation method for a long-span floor arch structure with arch-foot prestressed balance cables, comprising the following steps: Step 1: Zoning determination; Step 2: First tensioning of the arch-foot prestress; Step 3: Installation of the arch-foot section; Step 4: Construction of the overall hoisting section: The overall hoisting section is assembled and welded on the ground, a temporary tensioning assembly is installed on the lower chord of the overall hoisting section, and the overall hoisting section is tensioned, and the tensioning value is the horizontal thrust value generated at the end of the overall hoisting section; Hoisting frames are respectively installed at both ends of the overall hoisting section area of the floor arch structure, a set of hoisting frames is symmetrically arranged on both sides of each end of the overall hoisting section, a hoisting assembly is installed on the hoisting frame, and the overall hoisting section is hoisted and positioned through the hoisting assembly; Step 5: Installation of the closure section; Step 6: Unloading; Step 7: Tensioning. Through the close combination of various construction processes, the present application improves the installation efficiency of the floor arch structure, realizes the investment of lower measure costs, and has good economy.

Description

Technical Field

[0001] The present invention relates to the technical field of the installation of floor arches, and in particular to an installation method for a long-span floor arch structure with arch-foot prestressed balance cables. Background Art

[0002] Floor arch structures are commonly seen in buildings such as bridges, industries, and portal arches. For example, the ancient and modern Zhaozhou Bridge and other arch bridges are applied. Nowadays, floor arch structures are also used in public buildings with large space function requirements, appearing as the entrances of landmark buildings such as exhibition halls and railway stations. Such arch structures often solve the problem of the lateral thrust of the arch structure by adding prestressed balance cables at the lower part, while optimizing the steel consumption of the structure. However, facing the construction problems such as high structure, large span, and large component weight brought by such structures, the traditional construction plan has problems such as many high-altitude operations, high construction measure costs, long construction periods, and great difficulties in safety and quality control. Summary of the Invention

[0003] The present invention provides an installation method for a long-span floor arch structure with arch-foot prestressed balance cables, which adopts a combination of in-situ installation of arch feet, integral lifting of the middle section, and step-by-step tensioning of the permanent and temporary combination of prestressed cables, solves the problems of many high-altitude operations, difficult positioning, and low construction efficiency, and realizes safe, efficient, and lean construction.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions:

[0005] An installation method for a long-span floor arch structure with arch-foot prestressed balance cables of the present invention includes the following steps:

[0006] Step 1: Zoning determination: Divide the floor arch structure into pier seats, arch-foot sections, closure sections, and integral hoisting sections. The arch-foot sections are installed on the pier seats, and the closure sections connect the arch-foot sections and the integral hoisting sections;

[0007] Step 2: First tensioning of arch-foot prestress: Connect a concrete tie beam between the two pier seats, set prestressed cables in the concrete tie beam, and perform the first tensioning on the prestressed cables. The tensioning value is the horizontal thrust value generated by the floor arch structure under its own weight state;

[0008] Step 3: Installation of arch-foot sections: Install the arch-foot sections by the method of in-situ bulk installation at high altitude;

[0009] Step 4: Construction of integral hoisting sections: Assemble and weld the integral hoisting sections on the ground, install temporary tensioning components on the lower chord of the integral hoisting sections, and perform tensioning on the integral hoisting sections. The tensioning value is the horizontal thrust value generated at the ends of the integral hoisting sections;

[0010] Lifting frames are respectively installed at both ends of the overall hoisting section area of the floor arch structure. A set of lifting frames is symmetrically arranged on both sides at each end of the overall hoisting section. Lifting components are installed on the lifting frames, and the overall hoisting section is lifted into place through the lifting components;

[0011] Step 5: Installation of the closure section: The closure section is sliced, and the sliced units are assembled on the ground. A lifting machine is used to patch the sliced units at high altitude. When closing, the lower chord sliced units are installed first, and then the upper chord sliced units are installed. The closure sections at both ends of the floor arch structure are closed synchronously to form the effect of the floor arch structure after completion;

[0012] Step 6: Unloading: The floor arch structure is unloaded by gradually reducing the load through the lifting components;

[0013] Step 7: Tensioning: After the installation of the floor arch structure is completed and unloaded, the prestressed cables are tensioned, and the tensioning value cancels out the horizontal thrust of the floor arch structure.

[0014] By adopting the above scheme, the floor arch structure is reasonably partitioned. A combined scheme of in-situ installation at high altitude for the arch foot section, overall hoisting for the middle section, and block-by-block hoisting for the closure section is adopted, combined with the combined use of permanent and temporary prestressed cables for step-by-step tensioning to install the floor arch structure, ensuring the installation accuracy and structural performance of the floor arch structure and solving the problems of many high-altitude operations, difficult positioning, and low construction efficiency.

[0015] For the installation method of a large-span floor arch structure with arch-foot prestressed balance cables of the present invention, further, in step 2, the prestressed cables are tensioned at both ends. After one end is tensioned, the other end is supplemented and tensioned. During the tensioning process, the prestressed cables in all ducts are tensioned sequentially from bottom to top.

[0016] For the installation method of a large-span floor arch structure with arch-foot prestressed balance cables of the present invention, further, in step 3, a temporary support bracket is set below the arch foot section to support the arch foot section, and a steel mesh platform is erected below the arch foot section for workers to stand on the steel mesh platform to install the arch foot section.

[0017] By adopting the above scheme, aiming at the problem that it is difficult to use overall lifting and hoisting for the arch foot section with large local cross-sections of members and large weights of single members, an in-situ installation scheme at high altitude is adopted, and a steel mesh platform is installed based on the temporary support bracket to assist in the installation of the arch foot section, solving the problem of inconvenience in using a boom lift due to the complex structure of the arch foot section.

[0018] The installation method of a long-span floor arch structure with arch-foot prestressed balance cables of the present invention. Further, the expanded metal mesh platform includes longitudinal beams, cross beams and steel meshes. The longitudinal beams are connected between the pier bases and the temporary support scaffolds, and between the temporary support scaffolds. The cross beams are connected between the longitudinal beams to connect multiple longitudinal beams into a whole. The steel meshes are laid on the frame structure composed of the longitudinal beams and the cross beams to form a working platform.

[0019] By adopting the above scheme, a simple working platform is formed by connecting the longitudinal beams to the temporary support scaffolds. Workers stand on the working platform to install the arch-foot section. The working platform has a simple structure and is convenient to install, improving the installation efficiency of the arch-foot section.

[0020] The installation method of a long-span floor arch structure with arch-foot prestressed balance cables of the present invention. Further, in step 4, the temporary tensioning assembly includes temporary cables connected to both ends of the lower chord of the integral hoisting section, oil cylinders installed at both ends of the temporary cables, and anchors connecting the oil cylinders and the integral hoisting section.

[0021] By adopting the above scheme, since there will be tension in the integral hoisting section during the lifting stage, and due to the inconsistent horizontal heights of the inner and outer arches, there is a problem of inconsistent tension values on both sides. By installing the temporary cables, the tension of the integral hoisting section is controlled, which is convenient for controlling the aerial shape and stable state during the lifting process and is convenient for the installation of the closure section.

[0022] The installation method of a long-span floor arch structure with arch-foot prestressed balance cables of the present invention. Further, in step 4, the lifting frames are assembled by multiple groups of lattice standard sections, and section steel conversion platforms are respectively provided at the top and the top of each group of lifting frames.

[0023] By adopting the above scheme, assembling with standard structures is convenient for installation and disassembly and can be recycled.

[0024] The installation method of a long-span floor arch structure with arch-foot prestressed balance cables of the present invention. Further, the lifting assembly includes a transition beam, a conversion beam, a supporting beam, a lifting beam and a lifting oil cylinder. The supporting beam is installed on the conversion beam across two lifting frames. The conversion beam is installed on at least two groups of transition beams on the same lifting frame. The transition beams are installed on the section steel platforms;

[0025] The lifting beams are installed at intervals on the supporting beam, and the lifting oil cylinders are installed on the lifting beams for lifting the integral hoisting section.

[0026] By adopting the above scheme, the integral hoisting section is lifted into place by the lifting oil cylinders, and the lifting oil cylinders can also be used for unloading the subsequent floor arch structure, making the operation more convenient.

[0027] The installation method of a long - span floor - supported arch structure with arch - foot prestressed balance cables according to the present invention. Further, in step 6, the lifting reaction forces of all lifting cylinders are adjusted simultaneously at intervals of 10%, decreasing successively, and the lifting reaction forces of all lifting cylinders are adjusted to 0 kN in ten times; then the lifting components and the lifting frame are removed, and the unloading is completed.

[0028] The installation method of a long - span floor - supported arch structure with arch - foot prestressed balance cables according to the present invention. Further,

[0029] By adopting the above - mentioned scheme, through the step - by - step unloading of the lifting cylinders, the stability of the floor - supported arch structure during the conversion from the lifted state to the self - weight state is ensured.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. Through the close combination of various construction techniques, the installation efficiency of the floor - supported arch structure is improved in the present application, and the input of lower measure costs is realized, with good economy.

[0032] 2. Compared with the conventional method, the amount of high - altitude operation of the operators in the present application is smaller, and the operation safety risk of the construction personnel is lower.

[0033] 3. The present application adopts a construction technique that combines the tensioning processes of temporary cables and permanent prestressed cables, which improves the quality control and structural safety during the construction process; the quality control is reflected in that for the floor - supported arch in the overall lifting section during the construction process, the structural deformation that will occur during the lifting is offset by the measures of the temporary cables, so that after the lifting and positioning, the structure is not affected by deformation; regarding the structural safety, the horizontal thrust that will occur when the floor - supported arch structure enters the designed self - weight state after construction and forming is offset by the permanent prestressed cables, avoiding permanent structural deformation.

[0034] The present invention will be further described below with reference to the accompanying drawings. Description of the Drawings

[0035] Figure 1 It is a structural schematic diagram of the floor - supported arch structure installation completed according to the present invention;

[0036] Figure 2 It is a structural schematic diagram of the installation of the temporary support falsework and the steel mesh platform for the arch - foot section according to the present invention;

[0037] Figure 3 It is a structural schematic diagram of the distribution of the support falsework according to the present invention;

[0038] Figure 4 It is a structural schematic diagram of the ground assembly of the overall hoisting section according to the present invention;

[0039] Figure 5 It is a structural schematic diagram of the installation of the lifting frame and the lifting components according to the present invention;

[0040] Figure 6 Schematic diagram of the lifting structure for the integral hoisting section of the present invention;

[0041] Figure 7 Schematic diagram of the installation structure for the closure section of the present invention;

[0042] Figure 8 Schematic diagram of the lifting frame and lifting components of the present invention;

[0043] Figure 9 Schematic diagram of the structure of the lifting components of the present invention;

[0044] Figure 10 Schematic diagram of the support falsework structure of the present invention;

[0045] Figure 11 Schematic diagram of the structure of the temporary tensioning components of the present invention.

[0046] Reference numerals:

[0047] 1, pier seat; 2, arch foot section; 3, closure section; 4, integral hoisting section; 5, prestressed cable; 6, temporary support falsework; 7, expanded metal platform; 7.1, longitudinal beam; 7.2, cross beam; 8, support falsework; 9, temporary tensioning components; 9.1, temporary cable; 9.2, oil cylinder; 9.3, anchor; 10, lifting frame; 11, profiled steel platform; 12, lifting components; 12.1, transition beam; 12.2, conversion beam; 12.3, supporting beam; 12.4, lifting beam; 12.5, lifting oil cylinder; 12.6, lifting cable. Detailed implementation manners

[0048] As Figures 1 - 11 shown, the present invention discloses an installation method for a long-span floor arch structure with arch foot prestressed balance cables, including the following steps;

[0049] Step 1: Zoning determination: The floor arch structure of this application is a gradually changing quadrilateral structure, with both ends installed on the pier seats. The floor arch structure is divided into an arch foot section, a closure section, and an integral hoisting section. The floor arch structure is subjected to in-situ installation, block lifting, and high-altitude closure for three-zone division, and the entire construction process is checked and calculated using construction simulation software to ensure the feasibility of the plan. Among them, calculations and analyses are required for stages such as arch foot prestress tensioning, middle section block lifting, high-altitude closure, and unloading, so that the construction completion state is consistent with the design state; determine relevant construction measure parameters. The parameters mainly refer to the specific specification parameter values of various construction measure installation materials, tools, etc., obtain the bearing capacity requirements of the operation site and the installation and removal sequence of temporary measures, and guide the actual construction.

[0050] Step 2: First tensioning of the arch springing prestress: Due to the large span and large load area of the floor arch structure, the horizontal thrust generated at the arch springing imposes a great burden on the pile foundation. To resist the horizontal thrust at the arch springing, a concrete tie beam is connected between the two abutments, and prestressed cables are installed in the concrete tie beam to balance the horizontal thrust generated by the floor arch structure; the abutments need to be completely separated from the basement structures on both sides. After the construction of the abutment concrete pouring, the installation of the lower steel skeleton of the floor arch structure, the concrete tie beam pouring, and the prestressed cable installation are completed, when the concrete strength of the abutment and the concrete tie beam reaches 100%, the first tensioning of the prestressed cable is carried out. The prestressed cable is tensioned from both ends. After one end is tensioned, the other end is supplemented and tensioned. During the tensioning process, the prestressed cables in all ducts are tensioned sequentially from bottom to top until the prestress value reaches the value that offsets the horizontal thrust generated by the floor arch structure and then stops.

[0051] Step 3: Installation of the arch springing section: Facing the problems of large local cross-section, large weight of single components, large lifting weight after ground assembly, and difficult lifting of the floor arch structure, the construction method of high-altitude in-situ bulk assembly with temporary support scaffolds is adopted; due to the complex structure of the arch springing section and the inconvenience of using a boom truck, a steel mesh platform is erected under the arch springing section to cooperate with the installation, welding, inspection, and high-altitude docking of the closure section of the arch springing section. The steel mesh platform includes longitudinal beams, cross beams, and steel meshes. The longitudinal beams are connected between the abutments and the temporary support scaffolds, and between the temporary support scaffolds. The cross beams are connected between the longitudinal beams to connect multiple longitudinal beams into a whole. The steel mesh is laid on the frame structure composed of longitudinal beams and cross beams to form a working platform, and the staff stands on the working platform to install the arch springing section.

[0052] Step 4: Construction of the overall hoisting section: In order to facilitate the rapid docking of the ground arch structure at high altitude and reduce the construction period of the entire ground arch structure, the overall hoisting section is lifted into place at one time after being assembled and welded on the support frame. Due to the large cross-section of the ground arch structure rods and the heavy weight of a single component, all components are distributed to the site for assembly. After the overall hoisting section is assembled and welded on the ground, the segmented overall hoisting section is hoisted to the support frame for assembly and welding using a lifting machine. After welding is completed, a temporary tensioning assembly is installed on the lower chord of the overall hoisting section. The temporary tensioning assembly includes temporary cables connected to both ends of the lower chord of the overall hoisting section, oil cylinders installed at both ends of the temporary cables, and anchors connecting the oil cylinder and the overall hoisting section; after the overall hoisting section is assembled, the overall hoisting section is tensioned by the temporary tensioning assembly, and the tensioning value is the horizontal thrust value generated at the end of the overall hoisting section. The purpose of temporary cable tensioning is to control the aerial posture or structural deformation of the overall lifting section. After the overall lifting section is separated from the supporting frame, the arch structure will generate tension on both sides. Temporary cable tensioning is used to offset the horizontal thrust generated by the overall lifting section arch structure under its own weight and lifting loading state, so that the arch structure will not produce structural deformation caused by construction during the lifting process and after it is in place. After the entire ground arch is closed, the tension of the temporary construction cable is released.

[0053] The supporting frame uses the roadbed box as its foundation. To facilitate the setting of the cables of the overall lifting section, three rows of columns are set at each supporting point. Support beams are installed on the columns, and steel sections are used to adjust the elevation between the support beams and the overall lifting section.

[0054] Lifting frames are installed at both ends of the overall lifting section area of the ground arch structure. A group of lifting frames are symmetrically arranged on both sides of each end of the overall lifting section. The lifting frames are assembled from multiple groups of lattice standard sections, and the lattice standard sections are assembled and connected by flanges and screws. H-shaped steel conversion platforms are respectively provided at the top and bottom of each group of lifting frames. The steel platforms are mainly used to bear the force of the columns of the lifting frames and transfer the force to the roadbed box foundation. The bottom of the lifting frame uses the roadbed box as the foundation. Note that the placement of the roadbed box needs to avoid the prestressed cables between the piers.

[0055] A lifting assembly is installed on the top of the lifting frame, which includes a transition beam, a transfer beam, a supporting beam, a lifting beam and a lifting cylinder. The transition beam is installed on a steel platform, and the transfer beam is erected on two sets of transition beams on the same lifting frame. The supporting beam spans two lifting frames and is installed on the transfer beam. The supporting beam is a double-split setting, and a space is formed between the two supporting beams for the lifting rope of the lifting cylinder to pass through. The lifting beam is installed on the supporting beam, and the lifting cylinder is installed on the lifting beam. One end of the lifting rope is connected to the lifting cylinder, and the other end is connected to the overall lifting section. The number of lifting points and the type of lifting cylinder are determined according to the lifting weight, and the safety factor is not less than 1.2.

[0056] Step 5: Installation of the closure segment: Since the long-span ground arch structure has a long span, high heat conduction efficiency of the steel structure, and is greatly affected by temperature loads, the closure temperature should be analyzed with reference to the highest and lowest temperatures in the project location. The suitable closure temperature is 15°C ± 5°C. The closure segment is divided into pieces to form small assembly units for assembly on the ground, and a lifting machine is used to piecemeal fill and supplement at high altitude. During closure, the lower chord pieces are installed first, and then the upper chord pieces are installed. The closure segments at both ends of the ground arch structure need to be closed synchronously, and after completion, the ground arch structure effect is formed.

[0057] Step 6: Unloading: The process of unloading the ground arch structure is actually a process in which the structure changes from the lifting system to the self-bearing system. The method of gradually reducing the load using the lifting cylinders is used for unloading, and the unloading process is divided into three steps:

[0058] 1) After all the installations of the ground arch structure are completed and all welding work at all positions must be fully completed, the weld inspection personnel must conduct 100% inspection on the welds. The weld quality meets the design requirements. After passing the quality inspection and being overall stable, unloading begins;

[0059] 2) Adjust the lifting reaction forces of all lifting cylinders simultaneously at intervals of 10%, and decrease them successively. Adjust the lifting reaction forces of all lifting cylinders to 0 kN in ten times;

[0060] 3) Remove the lifting components and the lifting frame, and the unloading is completed.

[0061] Step 7: Tensioning: Adjust the tensioning of the prestressed cables according to the actual changes in the construction progress and the loads of the ground arch structure to ensure the structural stability and safety of the ground arch structure during the entire construction process. After the installation and unloading of the ground arch structure are completed, the prestressed cables are tensioned. The tensioning value cancels out the horizontal thrust of the ground arch structure to reduce the influence of the self-weight of the entire ground arch structure on the horizontal thrust of the pile foundation; The first tensioning is the pre-tensioning to offset the self-weight of the ground arch structure itself, and the second tensioning is the pre-tensioning to offset other loads applied to the ground arch structure.

[0062] The embodiments described above are only for describing the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. An installation method for a long-span floor arch structure with prestressed balance cables at the arch feet, characterized in that, It includes the following steps: Step 1: Partition determination: The floor arch structure is divided into pier seats, arch foot sections, closure sections, and integral hoisting sections. The arch foot sections are installed on the pier seats, and the closure sections connect the arch foot sections and the integral hoisting sections; Step 2: First tensioning of arch foot prestress: Connect a concrete tie beam between the two pier seats. Prestressed cables are arranged in the concrete tie beam, and the prestressed cables are tensioned for the first time. The tensioning value is the horizontal thrust value generated by the floor arch structure under its own weight; Step 3: Installation of arch foot sections: The arch foot sections are installed by the method of in-situ bulk erection at high altitude; Step 4: Construction of integral hoisting sections: The integral hoisting sections are assembled and welded on the ground. Temporary tensioning components are installed on the lower chords of the integral hoisting sections, and the integral hoisting sections are tensioned. The tensioning value is the horizontal thrust value generated at the ends of the integral hoisting sections; Lifting frames are respectively installed at both ends of the integral hoisting section area of the floor arch structure. A set of lifting frames is symmetrically arranged on both sides at each end of the integral hoisting section. Lifting components are installed on the lifting frames, and the integral hoisting sections are lifted into place through the lifting components; Step 5: Installation of closure sections: The closure sections are segmented. The segmented units are assembled on the ground, and a hoisting machine is used to patch the segmented units at high altitude. During closure, the lower chord segments are installed first, and then the upper chord segments are installed. The closure sections at both ends of the floor arch structure are closed synchronously, and after completion, the floor arch structure effect is formed; Step 6: Unloading: The floor arch structure is unloaded by gradually reducing the load through the lifting components; Step 7: Tensioning: After the installation and unloading of the floor arch structure are completed, the prestressed cables are tensioned, and the tensioning value cancels out the horizontal thrust of the floor arch structure; Among them, in Step 3, a temporary support bracket is arranged under the arch foot section to support the arch foot section, and a steel mesh platform is erected under the arch foot section for workers to stand on the steel mesh platform to install the arch foot section. The steel mesh platform includes longitudinal beams, cross beams, and steel meshes. The longitudinal beams are connected between the pier seats and the temporary support brackets and between the temporary support brackets. The cross beams are connected between the longitudinal beams to connect multiple longitudinal beams into a whole. The steel meshes are laid on the frame structure composed of the longitudinal beams and cross beams to form a working platform.

2. The installation method of a long-span floor arch structure with arch-foot prestressed balance cables according to claim 1, characterized in that: In Step 2, the prestressed cable tensioning is carried out by tensioning at both ends. After one end is tensioned, the other end is supplemented with tensioning. During the tensioning process, the prestressed cables in all ducts are tensioned sequentially from bottom to top.

3. The installation method of a long-span floor arch structure with arch foot prestressed balance cables according to claim 1, characterized in that: In Step 4, the temporary tensioning components include temporary cables connected to both ends of the lower chords of the integral hoisting sections, oil cylinders installed at both ends of the temporary cables, and anchors connecting the oil cylinders and the integral hoisting sections.

4. The installation method of a long-span floor arch structure with arch-foot prestressed balance cables according to claim 1, characterized in that: In Step 4, the lifting frames are assembled by multiple groups of lattice standard sections, and section steel conversion platforms are respectively arranged at the tops and bottoms of each group of lifting frames.

5. The installation method of a long-span floor arch structure with arch-foot prestressed balance cables according to claim 1, characterized in that: The lifting components include transition beams, conversion beams, supporting beams, lifting beams, and lifting oil cylinders. The supporting beams span across two lifting frames and are installed on the conversion beams. The conversion beams are installed on at least two groups of transition beams on the same lifting frame. The transition beams are installed on the section steel platforms; The lifting beams are installed at intervals on the supporting beams, and the lifting oil cylinders are installed on the lifting beams for lifting the integral hoisting sections.

6. The installation method of a long-span floor arch structure with arch-foot prestressed balance cables according to claim 1, characterized in that: In Step 6, adjust the lifting reaction force of all lifting cylinders simultaneously at intervals of 10%, decreasing successively, and adjust the lifting reaction force of all lifting cylinders to 0 kN in ten times; then remove the lifting assembly and the lifting frame, and the unloading is completed.

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