Large-span arc-shaped steel truss structure and construction method thereof

Abstract

The application discloses a large-span arc-shaped steel truss structure and a construction method for high-altitude scattered assembly by adopting a jig support, and belongs to the technical field of building steel structure construction. The structure comprises a plurality of arc-shaped main trusses, transverse connection trusses, chord support rods and node connecting pieces. The arc-shaped main truss is composed of an arc-shaped upper chord rod, a middle chord rod, a lower chord rod, a vertical web rod and an inclined web rod to form a triangular force unit. The chord rod is provided with a welding groove and a protrusion. The node is combined by a penetrating node and a cast steel node. The whole structure has strong anti-deformation and anti-lateral displacement capabilities. The application solves the problems of the existing large-span arc-shaped steel truss construction, such as difficult control of construction precision, unstable support and high cost. The application takes into account the structural safety and construction economy, and is suitable for large-span arc-shaped steel truss construction of large public buildings.

Description

Technical Field

[0001] This invention belongs to the field of construction of large-span curved steel truss structures, specifically relating to a large-span curved steel truss structure and its construction method. Background Technology

[0002] In projects such as commercial complexes, transportation hubs, and clusters of super high-rise buildings, large-span steel truss corridors have become core components for connecting multiple buildings and achieving functional linkages due to their large spans, excellent load-bearing performance, and aesthetically pleasing designs. These corridors often face construction challenges such as spans exceeding 30 meters, high installation heights, complex node structures, and numerous environmental constraints. Traditional high-altitude assembly methods are prone to structural deformation due to a lack of reliable support, while full-span scaffolding methods are limited by site conditions and are costly.

[0003] Based on practical experience in numerous large-span steel truss corridor projects, this construction method was specifically developed. Through core technologies such as customized formwork support system construction, layered and sectional high-altitude assembly, and full-process precision control, it effectively solves key issues in high-altitude assembly of large-span trusses, including deformation control, safety protection, and efficiency improvement. This method eliminates the need for large lifting equipment, is highly adaptable to different sites, and allows for precise control of installation accuracy. It is applicable to various types of large-span steel truss corridor construction and possesses significant technological advancement, practicality, and promotional value. Summary of the Invention

[0004] Based on the aforementioned shortcomings and deficiencies in existing technologies, one of the objectives of this invention is to provide a construction method for large-span arc-shaped steel trusses using a frame-supported high-altitude assembly method. This method is convenient to construct, requires no large lifting equipment, has a stable and reliable support system, can accurately control the arc accuracy and assembly quality of the steel truss, shortens the construction period, and reduces construction costs and safety risks.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] A large-span arc-shaped steel truss structure is characterized by comprising an arc-shaped main truss, transverse connecting trusses, chord support members, and node connectors. Several arc-shaped main trusses are evenly spaced along an arc-shaped trajectory. The transverse connecting trusses connect adjacent main trusses to form an integrated load-bearing system. The arc-shaped main truss includes an upper chord, a middle chord, a lower chord, and web members. The upper and lower chords are both weld-resistant arc-shaped box-shaped components, and the arc curvature of the upper chord is consistent with that of the lower chord. The middle chord is a variable cross-section circular tube. The web members include straight web members and diagonal web members. Several straight and diagonal web members are alternately connected between the upper chord and the middle chord, and between the middle chord and the lower chord, forming triangular load-bearing units.

[0007] The node connectors include intersecting nodes and cast steel nodes. The connections between the upper chord, middle chord, lower chord and web members are welded using intersecting nodes. The connections between adjacent arc-shaped main trusses and transverse connecting trusses are connected using cast steel nodes.

[0008] The arc-shaped main truss is installed between the inner ring shell steel columns; the embedded parts are embedded in the concrete beams of the lower basement roof slab; the formwork support system is erected on the basement roof slab below the lower chord, and the formwork transfer beam and steel plate are laid between the basement roof slab and the formwork support system; the upper chord, middle chord, and lower chord are all provided with welding grooves and welding protrusions at both ends; the upper chord, middle chord, and lower chord are segmented and installed, and then welded to the welding grooves and welding protrusions, with an inner lining plate at the joint; the inner lining plate is welded to the upper chord, middle chord, and lower chord segments simultaneously; the web members include vertical web members and diagonal web members, and the intersection nodes of the web members with the upper chord and lower chord are connected by full-penetration bevel welding, with the bevel form of the intersection node adjusted according to the angle between the web member and the upper chord, middle chord, and lower chord.

[0009] The construction method and steps are as follows;

[0010] Steel component factory processing and fabrication: According to the dimensions of the construction drawings, each steel component is processed and fabricated. Due to the pipe diameter and thickness, hot bending process is required for bending. According to the requirements of the steel pipe material, the current is increased to 300kw / h and the material is heated to 900 degrees. After all steel components are processed, they are rust-removed and anti-corrosion treated, marked with numbers, and after trial assembly in the factory and passing the test, they are transported to the construction site.

[0011] The temporary support frame uses an I-beam transfer beam to transfer the force to the concrete beam. First, embedded iron parts are placed at the corresponding positions on the concrete beam of the basement roof. Then, PL25 mm steel plates are welded on top of the embedded parts to raise the transfer beam. The transfer beam is then welded onto the plate, and the temporary support frame is welded on top of the transfer beam to transfer the force to the concrete beam.

[0012] Based on the parameters of the curved steel truss, determine the erection location, quantity, and height of the support frame. The support frames are evenly spaced along the length of the steel truss, and a number of support frames are set under each steel truss. The support frame consists of uprights and web members. The support frame is composed of components A, B, and C, which can be freely combined and expanded as needed during construction. The uprights of the support frame are connected by a flange system. Component B is bolted to components A and C. The uprights and web members in components A and C are intersected by welding.

[0013] The connecting truss of the inner ring shell structure was installed on the basement roof using a truck crane. First, the lower chord of the truss was installed. The lower chord of the truss was shipped to the site in three sections from the processing plant and was supported by four-way support jigs.

[0014] Install the lower chord of the inner ring shell truss and the steel beams between the lower chords of adjacent trusses to form an integral structure;

[0015] Install adjacent truss web members, and use I-beams to support four diagonal braces;

[0016] The upper chords of adjacent trusses are installed using a truck crane. The upper chords are shipped to the site in three sections from the processing plant. First, the two ends on the left and right sides are hoisted, and then the middle section is hoisted.

[0017] When hoisting the steel column above the lower chord of the curved truss, since the steel column is inclined, guy ropes are used to pull it to the upper chord of the adjacent truss that has been installed. The hooks are then released only after the bottom is welded and reinforced.

[0018] Install the arched truss steel columns and the steel beams between the upper chords of the steel connecting corridor trusses, as well as the diagonal bracing and steel beams between the steel columns;

[0019] After confirming that the steel truss structure is stable and the weld quality is up to standard, the jig is removed.

[0020] Compared with the prior art, the beneficial effects of this invention are:

[0021] 1. The large-span arc-shaped steel truss structure of the present invention adopts arc-shaped upper chord, middle chord, lower chord, straight web members, and diagonal web members to form triangular force-bearing units, which have reasonable force distribution and strong resistance to lateral displacement and deformation; the node connectors adopt a combination of intersecting nodes and cast steel nodes to adapt to different connection scenarios, ensure connection strength, and the overall structure has good stability and high durability, which can meet the usage requirements of large-span and high-altitude operation scenarios.

[0022] 2. The construction method of this invention adopts a frame support for high-altitude assembly, which does not require large lifting equipment, is less restricted by the site conditions, and has strong adaptability. The frame support system is constructed with steel sections, which can accurately control the arc accuracy and assembly elevation of the steel truss, reduce the cumulative assembly error, and ensure construction quality. The frame support system has undergone load testing and is stable and reliable, and can effectively bear the self-weight of the steel truss and the construction load, reducing the safety risks of high-altitude operations.

[0023] 3. The construction method of this invention involves the factory processing of steel components and on-site high-altitude assembly, which facilitates construction and shortens the on-site construction period. The segmented fabrication and transportation of steel components facilitates handling and hoisting, reducing transportation and construction costs. During the construction process, real-time monitoring, segmented verification, and timely adjustments are adopted to ensure that the assembly accuracy meets the requirements. Weld inspection and anti-corrosion and fireproofing treatment further guarantee the safety and durability of the structure. Attached Figure Description

[0024] Figure 1 This is a flowchart of the present invention;

[0025] Figure 2 This is a schematic diagram of the temporary formwork elevation;

[0026] Figure 3 This is a schematic diagram of a temporary tire frame assembly;

[0027] Figure 4 This is a schematic diagram of a large-span curved truss;

[0028] Figure 5 This is a schematic diagram of the overall truss structure;

[0029] Figure 6 This is a diagram showing the locations of the trusses and temporary support frames;

[0030] Figure 7 Schematic diagram of the connection node between the transfer beam and the basement roof slab;

[0031] Figure 8 Schematic diagram of temporary stabilization measures for the main truss box girder;

[0032] Figure 9 Schematic diagram of temporary fixing measures for curved vertical poles with guy ropes.

[0033] In the diagram: 1. Temporary frame diagonal web member, 2. Temporary frame upright, 3. Temporary frame horizontal web member, 4. Rib plate, 5. End plate, 6. Vertical web member, 7. Lower chord, 8. Middle chord, 9. Diagonal web member, 10. Upper chord, 11. Large-span arc truss, 12. Adjacent main truss, 13. Support frame transfer beam, 14. Elevating steel plate, 15. Embedded iron parts, 16. Square steel temporary support, 17. Guy rope, A. Temporary frame assembly, B. Temporary frame assembly, C. Temporary frame assembly. Detailed Implementation

[0034] To more clearly illustrate the embodiments of the present invention, specific implementation methods will be described below with reference to the accompanying drawings.

[0035] The arc-shaped main truss 11 is installed between the inner ring shell steel columns; the embedded part 15 is embedded in the concrete beam of the lower basement roof slab; the frame support system is erected on the basement roof slab below the lower chord 7, and the frame transfer beam 13 and the steel plate 14 are laid between the basement roof slab and the frame support system; the upper chord 10, the middle chord 8, and the lower chord 7 are respectively provided with welding grooves and welding protrusions at both ends; the upper chord 10 is segmented, the middle chord 8 is segmented, and the lower chord 7 is segmented. After the upper chord 10, the middle chord 8, and the lower chord 7 are segmented, they are hoisted and installed and welded to the welding grooves and welding protrusions. An inner lining plate is set at the joint, and the inner lining plate is welded synchronously with the upper chord 10 segment, the middle chord 8 segment, and the lower chord 7 segment; the web members include vertical web members 6 and diagonal web members 9. The two ends of the web members are connected to the intersection nodes of the upper chord 10 and the lower chord 7 by full penetration bevel welding. The bevel form of the intersection node is adjusted according to the angle between the web members and the upper chord 10, the middle chord 8, and the lower chord 7.

[0036] A construction method for large-span curved steel trusses using a formwork support for high-altitude assembly, based on the aforementioned large-span curved steel truss structure, includes the following steps:

[0037] Example 1

[0038] This project features a large-span steel truss connecting corridor with a span of 36 meters and a floor height ranging from 8.77 meters to 17.87 meters. The main steel structure components include box columns, circular tube columns, box beams, and H-beams.

[0039] Step 1: Construction Preparation

[0040] 1. Be familiar with the construction drawings, design disclosure documents and relevant specifications and standards, prepare special construction plans and safety emergency plans, and implement them after approval by the supervision unit and the construction unit.

[0041] 2. Conduct on-site surveys, clear the construction site, level the work surface, and test the bearing capacity of the foundation; plan component storage areas, processing areas, hoisting areas, and emergency access routes.

[0042] 3. Steel Component Factory Fabrication: Based on the dimensions in the construction drawings, various steel components are fabricated. The curved steel pipe columns used have curved shapes, with specifications of Φ500*20 and Φ600*25, made of Q355B; and specifications of Φ800*40, made of Q390B. Before fabrication, the steel pipes need to be bent. Due to the pipe diameter and thickness, a hot bending process is required. After the straight pipe is cut, an induction coil is placed on the section of the steel pipe to be bent using a pipe bending and pushing machine. A mechanical arm holds the pipe head, and a medium-frequency current is passed through the induction coil to heat the steel pipe. When the steel pipe reaches a plastic state, it is pushed forward with mechanical force at the rear end to bend it. The bent section is quickly cooled with a coolant. This process of heating, pushing, bending, and cooling is repeated to continuously bend the pipe. After all steel components are fabricated, they undergo rust removal and anti-corrosion treatment, are marked with numbers, and after successful trial assembly in the factory, they are transported to the construction site.

[0043] 4. Construction equipment and materials shall be brought to the site. All incoming materials and equipment shall be subject to quality inspection and may only be put into use after passing the inspection.

[0044] 5. Provide safety and technical briefings to construction personnel, and ensure that special operation personnel hold valid certificates to work.

[0045] Step 2: Installation of embedded parts and supports

[0046] The temporary support frame 2 uses an I-beam transfer beam 13 to transfer the force to the concrete beam. First, the embedded iron parts 15 are placed at the corresponding positions of the concrete beam on the basement roof. Then, a PL25 mm steel plate 14 is welded above the embedded parts to raise the transfer beam. The transfer beam is then welded onto the plate, and the temporary support frame 2 is welded above the transfer beam to transfer the force to the concrete beam.

[0047] Step 3: Erection of the frame support system

[0048] 1. Based on the parameters of the curved steel truss, determine the location, quantity, and height of the formwork. The formwork supports a height of 7.6 meters and a maximum support weight of 115 tons.

[0049] 2. During the erection of the formwork, a total station and a level are used to monitor the elevation and verticality in real time. Adjustable jacks are installed on the top of the formwork. After the formwork is erected, a load test is carried out, applying a load equivalent to 1.2 times the self-weight of the steel truss. After confirming that it is stable and reliable, the next process is carried out.

[0050] 3. Lay scaffold boards and guardrails on the top of the frame and install safety nets.

[0051] Step 4: High-altitude assembly construction

[0052] 1. The lower chord of the truss is divided into 3 sections (each section weighs about 3-4 tons), the upper chord is divided into 3 sections, and the web members are hoisted individually (weighing 0.5-1 ton); first lower chord 7 (to form a stable platform) → then web members 6 and 9 (triangular supports) → then upper chord 10 (closed frame); when hoisting the main truss box girder 7, because the section height of the main truss box girder 7 is relatively high, in order to ensure its stability and prevent tilting, after the main truss box girder 7 is hoisted into place, 100*5 square steel 16 tubes are used as temporary diagonal braces and welded to the upper part of the box girder and the temporary support frame cap. The hooks can only be loosened after the welding is firm.

[0053] 2. 100-ton truck crane working condition: main boom length 25.4m, working radius 12m, rated lifting capacity 15.8 tons, meeting the lifting requirements of single truss (≤8 tons) and steel column (≤8.14 tons).

[0054] 3. A 100-ton truck crane was used to hoist the adjacent truss 12 of the arc-shaped truss on the basement roof slab. First, the lower chord of the truss was hoisted. The lower chord of the truss was shipped to the site in three sections from the processing plant and supported by two support frames.

[0055] 4. Install the steel beam between the lower chord 7 of the inner ring shell truss and the lower chord of the adjacent truss 12 to form an integral structure.

[0056] 5. Install 12 web members of the adjacent truss, and use HI250*250*9*14 I-beams to support 4 diagonal braces.

[0057] 6. A 100-ton truck crane was used to install the upper chord of the adjacent truss 12. The upper chord was shipped to the site in three sections from the processing plant. First, the left and right ends were hoisted, and then the middle section was hoisted.

[0058] 7. Hoist the steel column 6 above the lower chord of the curved truss. Since this steel column has an inclination, use guy rope 17 to pull it to the upper chord position of the adjacent truss 12 that has been installed. After welding and reinforcing it at the bottom, the hook can be released.

[0059] 8. Install the arched truss 11 steel columns and steel connecting corridor truss 12 upper chord steel beams and steel column diagonal braces and steel beams. According to the construction drawings, hoist the web members to the designed positions of the lower chord and upper chord, adjust the verticality and angle of the web members, and weld the intersection nodes of the web members with the upper and lower chords. During welding, adjust the bevel form according to the included angle of the members to ensure the weld penetration.

[0060] Step 5: Removal of the frame support system

[0061] 1. After confirming that the steel truss structure is stable and the weld quality is qualified, the jig is removed;

[0062] 2. The unloading process is graded, synchronous, and symmetrical, with each grade unloading amount ≤ 20% of the total load; Grade 1 (50%): loosen the jacks to 50% load, observe for 24 hours, and the structural deformation ≤ L / 1000; Grade 2 (80%): continue to loosen to 20% load, observe for 12 hours, and the welds show no cracks; Grade 3 (100%): completely remove the supports and measure the final deflection. Settlement observation points are set at the mid-span and 1 / 4-span of the truss, and a precision level (DS05 grade) is used for measurement, with readings accurate to 0.1mm.

[0063] 3. Designated personnel will be on-site to monitor the situation, a warning area will be set up, and dismantled components will be promptly cleaned up, sorted, and stacked.

[0064] 4. After the frame is removed, clean up the construction site and inspect the surface of the steel truss.

[0065] Step 6: Weld inspection and subsequent treatment

[0066] 1. After all welding work is completed, all welds are subjected to ultrasonic and radiographic testing to ensure that there are no welding defects.

[0067] 2. After the weld inspection is qualified, clean the surface of the steel truss and carry out overall anti-corrosion and fireproofing treatment;

[0068] 3. After the anti-corrosion and fireproofing treatments are completed, the steel truss is subjected to a second precision check.

Claims

1. A large-span arc-shaped steel truss structure, characterized in that, The system comprises an arc-shaped main truss, transverse connecting trusses, chord support members, and node connectors. Several arc-shaped main trusses are evenly spaced along an arc-shaped trajectory. The transverse connecting trusses connect adjacent main trusses to form an overall force-bearing system. The arc-shaped main truss includes an upper chord, a middle chord, a lower chord, and web members. The upper and lower chords are both weld-resistant arc-shaped box-shaped components, and the arc curvature of the upper chord is consistent with that of the lower chord. The middle chord is a variable cross-section circular tube. The web members include straight web members and diagonal web members. Several straight and diagonal web members are alternately connected between the upper chord and the middle chord, and between the middle chord and the lower chord, forming a triangular force-bearing unit. The node connectors include intersecting nodes and cast steel nodes. The connections between the upper chord, middle chord, lower chord and web members are welded using intersecting nodes. The connections between adjacent arc-shaped main trusses and transverse connecting trusses are connected using cast steel nodes. The arc-shaped main truss (11) is installed between the inner ring shell steel columns; the embedded part (15) is embedded in the concrete beam of the lower basement roof slab; the frame support system is erected on the basement roof slab below the lower chord (7), and the frame transfer beam (13) and steel plate (14) are laid between the basement roof slab and the frame support system; the upper chord (10), middle chord (8), and lower chord (7) are respectively provided with welding grooves and welding protrusions at both ends, the upper chord (10) is segmented, the middle chord (8) is segmented, and the lower chord is segmented. (7) After the segmented hoisting and installation, the welding groove and welding protrusion are welded together, and an inner lining plate is set at the joint. The inner lining plate is welded to the upper chord (10), the middle chord (8), and the lower chord (7) in segments simultaneously. The web members include vertical web members (6) and diagonal web members (9). The two ends of the web members are connected to the intersection nodes of the upper chord (10) and the lower chord (7) by full penetration bevel welding. The bevel form of the intersection node is adjusted according to the angle between the web members and the upper chord (10), the middle chord (8), and the lower chord (7).

2. A construction method for a large-span arc-shaped steel truss structure as described in claim 1, characterized in that: The construction method and steps are as follows; Steel component factory processing and fabrication: According to the dimensions of the construction drawings, each steel component is processed and fabricated. Due to the pipe diameter and thickness, hot bending process is required for bending. According to the requirements of the steel pipe material, the current is increased to 300kw / h and the material is heated to 900 degrees. After all steel components are processed, they are rust-removed and anti-corrosion treated, marked with numbers, and after trial assembly in the factory and passing the test, they are transported to the construction site. The temporary support frame uses an I-beam transfer beam to transfer the force to the concrete beam. First, embedded iron parts are placed at the corresponding positions on the concrete beam of the basement roof. Then, PL25 mm steel plates are welded on top of the embedded parts to raise the transfer beam. The transfer beam is then welded onto the plate, and the temporary support frame is welded on top of the transfer beam to transfer the force to the concrete beam. Based on the parameters of the curved steel truss, determine the erection location, quantity, and height of the support frame. The support frames are evenly spaced along the length of the steel truss, and a number of support frames are set under each steel truss. The support frame consists of uprights and web members. The support frame is composed of components A, B, and C, which can be freely combined and expanded as needed during construction. The uprights of the support frame are connected by a flange system. Component B is bolted to components A and C. The uprights and web members in components A and C are intersected by welding. The connecting truss of the inner ring shell structure was installed on the basement roof using a truck crane. First, the lower chord of the truss was installed. The lower chord of the truss was shipped to the site in three sections from the processing plant and was supported by four-way support jigs. Install the lower chord of the inner ring shell truss and the steel beams between the lower chords of adjacent trusses to form an integral structure; Install adjacent truss web members, and use I-beams to support four diagonal braces; The upper chords of adjacent trusses are installed using a truck crane. The upper chords are shipped to the site in three sections from the processing plant. First, the two ends on the left and right sides are hoisted, and then the middle section is hoisted. When hoisting the steel column above the lower chord of the curved truss, since the steel column is inclined, guy ropes are used to pull it to the upper chord of the adjacent truss that has been installed. The hooks are then released only after the bottom is welded and reinforced. Install the arched truss steel columns and the steel beams between the upper chords of the steel corridor truss, as well as the diagonal bracing and steel beams between the steel columns; After confirming that the steel truss structure is stable and the weld quality is up to standard, the jig is removed.

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