Truss segmented hoisting method in limited space

Abstract

The invention relates to the technical field of building construction, in particular to a truss segmented hoisting method in a limited space, which comprises the following specific steps: S100, surveying, setting out and setting positioning points; s200, a latticed column and carrying pole beam supporting system is built; s300, the steel truss is designed and hoisted in a segmented mode; s300, the steel truss is designed and hoisted in a segmented mode; s310, synchronous preparation of double datum points before hoisting is carried out; s320, the GJ-1 and the GJ-3 are synchronously hoisted; s330, GJ-2 hoisting and system closing are carried out; s400, the web members and the upper chord members are bulk-packed at high altitude; and S500, stable system construction and temporary support transition are carried out. The temporary supporting platform is constructed through the latticed columns and the carrying pole beams, large machines do not need to enter a limited space, truss installation can be completed through tower crane segmented hoisting, and the problem that the large machines cannot enter is solved.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, in particular to a truss segmented hoisting method in a confined space. Background Art

[0002] The construction of large venues often requires installing long-span steel truss structures within the building. However, confined spaces, such as those within building floors, often face challenges such as the inaccessibility of large machinery and insufficient tower crane lifting capacity. Traditional integral or segmented hoisting methods are difficult to apply, resulting in high construction costs, significant safety risks, and difficulty controlling installation precision. Summary of the Invention

[0003] In order to solve the problems in the prior art, the present invention provides a method for truss segmented hoisting in a confined space. The specific technical solution is as follows:

[0004] The specific steps of the truss segmented lifting method in confined space are as follows:

[0005] S100, measurement and layout and positioning point setting;

[0006] S200, construction of lattice column and shoulder beam support system;

[0007] S300, steel truss segment design and erection;

[0008] S300, steel truss segment design and erection;

[0009] S310, simultaneous preparation of dual reference points before lifting;

[0010] S320, GJ-1 and GJ-3 are hoisted simultaneously;

[0011] S330, GJ-2 hoisting and system closure;

[0012] S400, belly bars and top chords are installed in bulk at high altitude;

[0013] S500, stable system construction and temporary support transition.

[0014] As a further technical solution of the present invention, the specific steps of S100 are as follows:

[0015] S110, plane positioning and laying out;

[0016] S111, baseline establishment;

[0017] Taking the building axis as the reference, use a total station to measure and set two mutually perpendicular control lines on the raft foundation, namely the X axis and the Y axis, as the positioning reference for the lattice columns and shoulder beams;

[0018] S112, lattice column positioning point setting;

[0019] According to the support system layout diagram, mark the center points of the four lattice columns on the control line, numbered G1 to G4. The spacing must match the length of the shoulder beam. Mark the center of each circle with red paint and drive in steel bars as marks.

[0020] S120, elevation control;

[0021] S121, Benchmark elevation measurement:

[0022] Measure and set the elevation control line on the concrete column as the elevation benchmark for lattice column installation;

[0023] S122, embedded parts top surface elevation:

[0024] Embed steel plate embedded parts at the lattice column positioning points, and control the top surface elevation to be flush with the top surface of the raft foundation;

[0025] S130, shoulder pole beam positioning line mark;

[0026] On the embedded parts of the lattice columns, the axis position of the shoulder beam is projected with a total station and marked on the surface of the embedded parts with a stylus as a basis for the plane positioning of the shoulder beam installation.

[0027] As a further technical solution of the present invention, the specific steps of S200 are as follows:

[0028] S210, lattice column segment assembly and hoisting;

[0029] S211, ground segment assembly;

[0030] Assemble the lattice columns in sections on a leveled site, and use angle steel bars to connect the main limbs to form a spatial truss structure;

[0031] S212, Hoisting and Temporary Fixing;

[0032] The first section of lattice columns was hoisted by a tower crane, aligned with the center line of the embedded parts, temporarily fixed with anchor bolts, verticality corrected with a theodolite, and temporarily fixed with two guy ropes;

[0033] The middle section and the top section are hoisted in sequence, and the sections are connected with flanges and high-strength bolts, and the tie bars are welded to form an integral column;

[0034] S220, large beam connection and reinforcement;

[0035] S221, large beam installation;

[0036] A large crossbeam is set longitudinally in the middle of the lattice column to connect adjacent lattice columns to form a horizontal support system;

[0037] S222, guy rope reinforcement;

[0038] Four guy ropes are installed on the top of each lattice column, corresponding to the four directions of east, south, west and north, and fixed to the ground anchors;

[0039] S230, shoulder pole beam hoisting and node structure;

[0040] S231, segmented splicing of shoulder-pole beams;

[0041] The shoulder pole beam is divided into two sections and spliced on the ground, and the splicing is connected by groove welding or high-strength bolts;

[0042] S232, lifting and positioning of shoulder pole beam;

[0043] Use a tower crane to hoist the shoulder beam to the top of the lattice column and place it on the column top support in the direction perpendicular to the truss;

[0044] S233, diagonal support setting;

[0045] An inclined support is added at the connection between the lattice column and the shoulder beam. The angle between the support and the horizontal plane is 45° to 60°, and the two ends are welded to the main limb of the lattice column and the flange of the shoulder beam to form a triangular stable node.

[0046] As a further technical solution of the present invention, the specific steps of S400 are as follows:

[0047] S410, quick installation of belly bars;

[0048] First, install the vertical web members corresponding to the GJ-2 to form a triangular unit of "lower chord-web-upper chord", then install the diagonal web members. The web members and the lower chord are connected by bolts. After installation, the truss forms a stable structure of "fixed at both ends + middle support", and the temporary guy ropes on the shoulder beam are removed;

[0049] S420, upper chord and hanging layer adjustment;

[0050] According to the slope of the truss, the upper chord is hoisted section by section from one end to the other, and the hanging rod is connected to the lower beam with bolts to form a hanging system.

[0051] As a further technical solution of the present invention, the specific steps of S500 are as follows:

[0052] S510, stable system construction;

[0053] S511, quick installation of out-of-plane supports;

[0054] After the single steel truss is hoisted, the stabilization system is constructed, with priority given to installing simply supported beams and diagonal supports perpendicular to the truss to form a spatially stable frame.

[0055] S512, simply supported beam connection process;

[0056] Align one end of the simply supported beam with the node of the upper chord of the truss and insert temporary bolts. Align the other end with the adjacent truss node and also temporarily fix it to ensure that the beam is level.

[0057] S513, diagonal support stress reinforcement;

[0058] The diagonal support and truss nodes are connected by "node plate + welding". After installation, the pre-tension of the diagonal support is tested with a dynamometer and adjusted with basket bolts to ensure that the support system is evenly stressed.

[0059] S520, temporary support transition;

[0060] S521, first uninstallation;

[0061] Lift the shoulder beam with a jack to release the top support force of the lattice column. Use the stress sensor to confirm that the shoulder beam load has been reduced by 50%. Use oxyacetylene to cut the top steel support of the lattice column. After cutting, remove the jack, observe for 1 hour, and record the displacement meter data.

[0062] S522, second unloading;

[0063] Repeat the above steps and cut the steel again until the lattice column is completely separated from the shoulder beam and the reaction force of the truss support reaches the design value. During the unloading process, the cutting is carried out synchronously at multiple positions to avoid eccentric force on the support system. After unloading is completed, the lattice column and shoulder beam are removed and the site is cleaned up.

[0064] As a further technical solution of the present invention, the specific steps of S310 are as follows:

[0065] S311, positioning of double support points of shoulder pole beam;

[0066] Mark the positioning lines of GJ-1 and GJ-3 on the shoulder pole beam, verify the coordinates with a total station, place adjustable steel pads at the supports at both ends of the shoulder pole beam, and pre-adjust the elevation to the design value.

[0067] S312, double-segment spreader synchronization inspection;

[0068] Prepare two sets of 4-point shoulder pole slings, calculate the lifting point positions according to the center of gravity of GJ-1 and GJ-3, and ensure that the components are level during lifting.

[0069] As a further technical solution of the present invention, the specific steps of S320 are as follows:

[0070] S321, GJ-1 hoisting;

[0071] The tower crane lifts GJ-1 above the shoulder-pole beam and slowly moves it above the left support point. The guy rope is used to control the swing of the component so that the bottom axis is aligned with the shoulder-pole beam positioning line. The left end of the component is temporarily fixed to the shoulder-pole beam with bolts. The right end is connected to the ground anchor with a guy rope to form a unilateral constraint. The deviation of the axis of the left end of the component is measured with a total station, and the elevation is measured with a level. The pad is fine-tuned with a jack until it meets the verticality and elevation requirements. A temporary support steel plate is welded to ensure the stability of the left end.

[0072] S322, GJ-3 hoisting

[0073] After GJ-1 is fixed, hoist GJ-3 to the right support point. The process is the same as GJ-1.

[0074] After the two ends are hoisted in sections, measure the mid-span distance to determine whether the measured value deviates from the theoretical value. If there is a deviation, adjust it through the oblong hole of the GJ-2 interface bolt;

[0075] S323, double-segment temporary fixation and stabilization;

[0076] After the two end segments are fixed, the two ends of the shoulder beam are subjected to force at the same time. The simply supported beams corresponding to the two end segments are immediately installed and temporarily connected to the truss nodes with high-strength bolts to form a "truss-simply supported beam" out-of-plane stability system.

[0077] As a further technical solution of the present invention, the specific steps of S330 are as follows:

[0078] S331, interface preprocessing;

[0079] Check the dimensions of the GJ-1 and GJ-3 interfaces, and polish the interface steel plates until they are shiny and have a groove angle of 45°.

[0080] S332, GJ-2 hoisting and docking;

[0081] Lift GJ-2 with a tower crane to the top of the mid-span, and slowly move it to the interface. First, align it with the GJ-1 interface and install temporary bolts. Then, align it with the GJ-3 interface and install temporary bolts as well.

[0082] First weld the web plates of the GJ-1 and GJ-2 interfaces, then weld the web plates of the GJ-3 and GJ-2 interfaces, and finally weld the flange plates.

[0083] The beneficial effects of the present invention are as follows:

[0084] (1) Temporary support system replaces large machinery:

[0085] Lattice columns and shoulder beams are used to construct a temporary support platform. There is no need for large machinery to enter the confined space. The truss installation can be completed by lifting in sections through a tower crane, solving the problem of large machinery being unable to enter.

[0086] (2) Synchronous lifting at both ends and closing in the middle:

[0087] The GJ-1 and GJ-3 structures were hoisted simultaneously in sections at both ends. Using a four-point lifting pole sling, the lifting point positions were calculated based on the component's center of gravity to ensure the component remained level during installation. Once both ends were secured, simply supported beams were immediately installed to form a "truss-simply supported beam" out-of-plane stability system. This process simultaneously applied force to both ends of the pole beam, conforming to linear force laws and avoiding the eccentric forces and cumulative errors that can occur with traditional, section-by-section hoisting.

[0088] (3) Rapid and stable installation of the web and upper chord:

[0089] The web members are installed in the order of "vertical first, then diagonal." The vertical web members corresponding to the GJ-2 are installed first to form a triangular unit of "lower chord-web-upper chord." The diagonal web members are then installed. The web members and lower chord are connected by bolts with a final tightening torque of 290 N·m. This installation sequence allows the truss to quickly form a stable "fixed at both ends + middle support" structure, allowing for the timely removal of the temporary guy ropes on the shoulder beams, shortening the time for high-altitude operations and reducing safety risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Figure 1 A schematic diagram of the lattice column and shoulder beam support system is shown;

[0091] Figure 2 The process flow chart of steel truss segmented hoisting is shown;

[0092] Figure 3 A schematic diagram of the truss stabilization system and temporary unloading is shown. DETAILED DESCRIPTION

[0093] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0094] In this embodiment, the equipment and tools mainly include: QTZ450 tower crane; 4-point shoulder pole sling with a load-bearing capacity of 10t; Φ12mm steel wire rope and shackle, 5t level; lattice column: ∠140×10 angle steel + ∠75×6 tie bar; shoulder pole beam: HW400×400×13 / 21 steel; total station with an accuracy of ±2mm+2ppm, used for lattice column positioning and layout; level, DS3, with an accuracy of ±3mm / km, for controlling elevation; steel tape measure, for verifying component dimensions.

[0095] The specific steps of the truss segmented lifting method in confined space are as follows:

[0096] S100, measurement and layout and positioning point setting;

[0097] S110, plane positioning and laying out;

[0098] S111, baseline establishment;

[0099] Taking the building axis as the reference, use a total station to measure and set two mutually perpendicular control lines on the raft foundation, namely the X axis and the Y axis, as the positioning reference for the lattice columns and shoulder beams;

[0100] S112, lattice column positioning point setting;

[0101] According to the support system layout diagram, mark the center points of the four lattice columns on the control line, numbered G1 to G4. The spacing must match the length of the shoulder beam. Mark the center of each circle with red paint and drive in Φ16mm steel bars as marks.

[0102] It should be noted that the spacing in the above S112 must match the length of the shoulder pole beam, which means it is equal. For example, the shoulder pole beam is 16m long, the spacing between G1 and G2 is 16m, and the Φ16mm steel bar must be 50mm exposed above the ground.

[0103] S120, elevation control;

[0104] S121, Benchmark elevation measurement:

[0105] Measure and set a +30.000m elevation control line on the concrete column as the lattice column installation elevation benchmark; this can be achieved using the round-trip measurement method, with a closure error of ≤±3√nmm, where n is the number of measuring stations;

[0106] S122, embedded parts top surface elevation:

[0107] Embed 500mm×500mm×10mm steel plate embedded parts at the lattice column positioning points. The top surface elevation is controlled to be flush with the top surface of the raft foundation. Use a level to monitor the pouring process to ensure the flatness of the top surface of the embedded parts.

[0108] S130, shoulder pole beam positioning line mark;

[0109] On the embedded parts of the lattice columns, the axis position of the shoulder beam is projected with a total station and marked on the surface of the embedded parts with a stylus as a basis for the plane positioning of the shoulder beam installation.

[0110] Through the above steps, we ensure that the construction preparation is sufficient and the measurement and positioning are accurate, laying the foundation for the subsequent lattice column installation and truss segmented lifting.

[0111] S200, construction of lattice column and shoulder beam support system;

[0112] S210, lattice column segmented assembly and hoisting;

[0113] S211, ground segment assembly;

[0114] Assemble the lattice columns in sections on a leveled site, and use angle steel tie bars to connect the main limbs to form a spatial truss structure. The tie bar spacing is ≤1.5m, and the verticality of the formed column is ≤H / 1000, where H is the section height, and the diagonal deviation is ≤5mm.

[0115] S212, Hoisting and Temporary Fixing;

[0116] The first section of the lattice column is hoisted by a tower crane, aligned with the center line of the embedded parts, temporarily fixed with anchor bolts, and verticality corrected with a theodolite. Two cables are temporarily installed to secure the column. The angle between the cables and the ground is 45° to 60°.

[0117] The middle section and the top section are hoisted in sequence, and the sections are connected with flanges and high-strength bolts, and the tie bars are welded to form an integral column;

[0118] S220, large beam connection and reinforcement;

[0119] S221, large beam installation;

[0120] A large crossbeam is set longitudinally in the middle of the lattice column to connect adjacent lattice columns to form a horizontal support system;

[0121] The large crossbeam and lattice columns are connected by welded steel plate nodes to ensure that the lattice columns bear the load in a coordinated manner;

[0122] S222, guy rope reinforcement;

[0123] Four guy ropes are installed on the top of each lattice column, corresponding to the four directions of east, south, west and north respectively. They are fixed to the ground anchors and the tightness is adjusted by the turnbuckles to ensure that the lateral displacement of the lattice column is ≤5mm during the lifting process.

[0124] S230, shoulder pole beam hoisting and node structure;

[0125] S231, segmented splicing of shoulder-pole beams;

[0126] The shoulder pole beam is divided into two sections and spliced on the ground, and the joints are connected by groove welding or high-strength bolts.

[0127] S232, lifting and positioning of shoulder pole beam;

[0128] Use a tower crane to lift the shoulder pole beam to the top of the lattice column and place it on the column top support along the vertical truss direction; adjust the shoulder pole beam elevation and axis so that the error is ≤±5mm and the horizontality is ≤L / 1000, where L is the length of the shoulder pole beam, and use M24 bolts to temporarily fix it to the lattice column.

[0129] S233, diagonal support setting;

[0130] Add an inclined support at the connection between the lattice column and the shoulder beam. The angle between the support and the horizontal plane is 45° to 60°. The two ends are welded to the main limb of the lattice column and the flange of the shoulder beam respectively. The weld length is ≥100mm to form a triangular stable node.

[0131] Through the above steps, it can be ensured that the lattice column and shoulder beam support system has sufficient strength, rigidity and stability, providing a safe and reliable support platform for the subsequent high-altitude bulk loading of steel trusses.

[0132] S300, steel truss segment design and erection;

[0133] S310: Synchronous preparation of dual reference points before lifting;

[0134] S311, positioning of double support points of shoulder pole beam;

[0135] Mark the positioning lines of GJ-1 and GJ-3 on the shoulder pole beam, and use a total station to verify the coordinates. The deviation should be ≤2mm. Adjustable steel pads should be placed at the supports at both ends of the shoulder pole beam, and the elevation should be pre-adjusted to the design value with an error of ≤±1mm.

[0136] S312, double-segment spreader synchronization inspection;

[0137] Prepare two sets of 4-point shoulder pole slings, calculate the lifting point positions according to the center of gravity of GJ-1 and GJ-3, and ensure that the components are level during lifting.

[0138] S320, GJ-1 and GJ-3 are hoisted simultaneously;

[0139] S321, GJ-1 hoisting;

[0140] The tower crane lifted GJ-1 to 1.2m above the shoulder-pole beam and slowly moved it above the left support point. The guy rope was used to control the swing of the component so that the bottom axis was aligned with the shoulder-pole beam positioning line. The left end of the component was temporarily fixed to the shoulder-pole beam with M20 bolts. The right end was connected to the ground anchor with a guy rope to form a unilateral constraint. The axis deviation of the left end of the component was measured with a total station, and the elevation was measured with a level. The pad was fine-tuned with a jack until it met the verticality and elevation requirements. A temporary support steel plate was welded to ensure the stability of the left end.

[0141] S322, GJ-3 hoisting

[0142] Within 1 hour after GJ-1 is fixed, hoist GJ-3 to the right support point, following the same process as GJ-1;

[0143] After the sections at both ends are hoisted, measure the mid-span distance to determine whether the measured value deviates from the theoretical value. If there is a deviation, adjust it through the oblong hole of the GJ-2 interface bolt.

[0144] S323, double-segment temporary fixation and stabilization;

[0145] After the two ends of the segment are fixed, the two ends of the shoulder beam are stressed at the same time, and the corresponding simply supported beams of the two end segments are immediately installed and temporarily connected to the truss nodes with high-strength bolts to form a "truss-simply supported beam" out-of-plane stability system;

[0146] S330, GJ-2 hoisting and system closure;

[0147] S331, interface preprocessing

[0148] Check the GJ-1 and GJ-3 interface dimensions:

[0149] The spacing error is ≤±5mm. If the actual spacing is 23.81m, the GJ-2 processing length is shortened by 10mm (to allow for welding shrinkage); if the spacing is 23.79m, an 8mm thick steel plate is added at the interface.

[0150] The interface steel plate is polished until the metallic luster is exposed, and the groove angle is 45° to ensure the welding quality.

[0151] S332, GJ-2 hoisting and docking;

[0152] Lift GJ-2 by a tower crane to 0.5m above the mid-span, then slowly move it to the interface. First, align it with the GJ-1 interface and install three M24 temporary bolts. Then, align it with the GJ-3 interface and install temporary bolts in the same manner. During this process, the tower crane can be slightly raised and lowered to adjust the interface misalignment to ≤2mm. If necessary, a hoist can be used to assist in alignment.

[0153] First weld the web of the GJ-1 and GJ-2 interfaces, then weld the web of the GJ-3 and GJ-2 interfaces, and finally weld the flange plates; that is, weld from the middle to both ends. However, it should be noted that a laser rangefinder is used to monitor the mid-span deflection during the welding process, and a measurement is taken after each weld is completed. If the deflection increment is greater than 0.5mm, suspend welding and adjust the welding sequence.

[0154] Through the above steps, the two end segments are used as reference points, and the axis and elevation are synchronously corrected by the total station. The middle segment GJ-2 can be adjusted according to the actual distance between the two ends to avoid cumulative errors;

[0155] Balanced force system: Both ends of the shoulder pole beam are subjected to force at the same time, and the mid-span deflection is generated step by step, which conforms to the linear force law and has a higher safety factor of the support system.

[0156] Stability is significantly improved: After the two ends are fixed in sections, out-of-plane simply supported beams and diagonal supports are immediately installed to form a "spatially stable frame". When the middle section is hoisted, the structure has stronger resistance to wind loads and construction loads.

[0157] It should be noted that GJ-1, GJ-2, and GJ-3 are segment numbers for large-span flat steel trusses, which are used to distinguish different segment components of the truss during lifting construction.

[0158] S400, belly bars and top chords are installed in bulk at high altitude;

[0159] S410, quick installation of belly bars;

[0160] First, install the vertical webs corresponding to the GJ-2 to form a triangular unit of "bottom chord-web-top chord". Then install the diagonal webs. The webs and bottom chords are connected by bolts with a final tightening torque of 290 N·m. After installation, the truss forms a stable structure of "fixed ends + middle support". Remove the temporary guy ropes on the shoulder beam.

[0161] S420, upper chord and hanging layer adjustment;

[0162] According to the slope of the truss, the upper chord is hoisted from one end to the other in sections, the elevation of the top surface of the upper chord is monitored by a total station, and the slope is adjusted using a bolt adjustment plate;

[0163] Connect the hanging rod to the lower HM200×200 secondary beam with high-strength bolts to form a hanging system; ensure that the verticality of the hanging rod is ≤L / 1000, L=2.4m, and the allowable deviation is ≤2.4mm.

[0164] S500, stable system construction and temporary support transition;

[0165] S510, stable system construction;

[0166] S511, quick installation of out-of-plane supports;

[0167] After the single steel truss is hoisted, the construction of the stabilization system is started, with priority given to installing simply supported beams and diagonal supports perpendicular to the truss to form a spatially stable frame.

[0168] Component parameters:

[0169] Simply supported beam: HM200×200×8×12, the length is determined according to the truss spacing, and both ends are connected to the truss nodes through 10.9 grade high-strength bolts.

[0170] Diagonal support: ∠125×10 angle steel, with an angle of 45°~60° with the lower chord of the truss, one end welded to the truss node plate, and the other end welded to the embedded concrete column part.

[0171] S512, simply supported beam connection process;

[0172] One end of the simply supported beam is aligned with the node of the upper chord of the truss, and three M20 temporary bolts are inserted. The other end is aligned with the adjacent truss node and temporarily fixed as well to ensure that the beam is level. The bolts are tightened according to the principle of "from the middle to both ends". 10% of the nodes are randomly inspected, and the torque qualification rate is 100%. For nodes that are required to be welded by the design, groove welding is adopted with a weld leg height of 8mm, and magnetic particle inspection is carried out after welding.

[0173] S513, diagonal support stress reinforcement;

[0174] The diagonal support and truss nodes are connected by "node plate + welding". After installation, the pre-tension of the diagonal support is tested with a dynamometer and adjusted with basket bolts to ensure that the support system is evenly stressed.

[0175] The node plate is 12mm thick and is welded to the lower chord and diagonal support of the truss on both sides. The weld length is ≥150mm and the height is ≥8mm.

[0176] S520, temporary support transition;

[0177] S521, first uninstallation;

[0178] The jack lifts the shoulder beam to release the top support force of the lattice column. The stress sensor confirms that the load on the shoulder beam is reduced by 50%. Oxyacetylene is used to cut the top steel support of the lattice column. After cutting, the jack is withdrawn, and the observation is carried out for 1 hour, and the displacement meter data is recorded.

[0179] S522, second unloading;

[0180] Repeat the above steps and cut 5mm steel again until the lattice column is completely separated from the shoulder beam and the reaction force of the truss support reaches the design value. During the unloading process, multi-position cutting is performed synchronously to avoid eccentric force on the support system. After unloading is completed, the lattice column and shoulder beam are removed and the site is cleaned up.

[0181] Through the above steps, the "equal load graded unloading" method is adopted to transfer the temporary support load to the truss self-supporting system in two times, unloading 50% of the load each time to ensure a smooth transition of the internal force of the structure.

[0182] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same.

Claims

1. The truss segmented hoisting method in a confined space is characterized by: The specific steps are as follows: S100, measurement and layout and positioning point setting; S200, construction of lattice column and shoulder beam support system; S300, steel truss segment design and erection; S300, steel truss segment design and erection; S310, simultaneous preparation of dual reference points before lifting; S320, GJ-1 and GJ-3 are hoisted simultaneously; S330, GJ-2 hoisting and system closure; S400, belly bars and top chords are installed in bulk at high altitude; S500, stable system construction and temporary support transition.

2. The method for hoisting trusses in sections in a confined space according to claim 1, characterized in that: The specific steps of S100 are as follows: S110, plane positioning and laying out; S111, baseline establishment; Taking the building axis as the reference, use a total station to measure and set two mutually perpendicular control lines on the raft foundation, namely the X axis and the Y axis, as the positioning reference for the lattice columns and shoulder beams; S112, lattice column positioning point setting; According to the support system layout diagram, mark the center points of the four lattice columns on the control line, numbered G1 to G4. The spacing must match the length of the shoulder beam. Mark the center of each circle with red paint and drive in steel bars as marks. S120, elevation control; S121, benchmark elevation measurement; Measure and set the elevation control line on the concrete column as the elevation benchmark for lattice column installation; S122, embedded parts top surface elevation: Embed steel plate embedded parts at the lattice column positioning points, and control the top surface elevation to be flush with the top surface of the raft foundation; S130, shoulder pole beam positioning line mark; On the embedded parts of the lattice columns, the axis position of the shoulder beam is projected with a total station and marked on the surface of the embedded parts with a stylus as a basis for the plane positioning of the shoulder beam installation.

3. The method for hoisting trusses in sections in a confined space according to claim 2, characterized in that: The specific steps of S200 are as follows: S210, lattice column segmented assembly and hoisting; S211, ground segment assembly; Assemble the lattice columns in sections on a leveled site, and use angle steel bars to connect the main limbs to form a spatial truss structure; S212, Hoisting and Temporary Fixing; The first section of lattice columns was hoisted by a tower crane, aligned with the center line of the embedded parts, temporarily fixed with anchor bolts, verticality corrected with a theodolite, and temporarily fixed with two guy ropes; The middle section and the top section are hoisted in sequence, and the sections are connected with flanges and high-strength bolts, and the tie bars are welded to form an integral column; S220, large beam connection and reinforcement; S221, large beam installation; A large crossbeam is set longitudinally in the middle of the lattice column to connect adjacent lattice columns to form a horizontal support system; S222, guy rope reinforcement; Four guy ropes are installed on the top of each lattice column, corresponding to the four directions of east, south, west and north, and fixed to the ground anchors; S230, shoulder pole beam hoisting and node structure; S231, segmented splicing of shoulder-pole beams; The shoulder pole beam is divided into two sections and spliced on the ground, and the splicing is connected by groove welding or high-strength bolts; S232, lifting and positioning of shoulder pole beam; Use a tower crane to hoist the shoulder beam to the top of the lattice column and place it on the column top support in the vertical truss direction; S233, diagonal support setting; An inclined support is added at the connection between the lattice column and the shoulder beam. The angle between the support and the horizontal plane is 45° to 60°, and the two ends are welded to the main limb of the lattice column and the flange of the shoulder beam to form a triangular stable node.

4. The method for hoisting trusses in sections in a confined space according to claim 1, characterized in that: The specific steps of S400 are as follows: S410, quick installation of belly bars; First, install the vertical web members corresponding to the GJ-2 to form a triangular unit of "bottom chord-web-top chord". Then install the diagonal web members. The web members and bottom chord members are connected with bolts. After installation, the truss forms a stable structure of "fixed at both ends + middle support". Remove the temporary guy ropes on the shoulder beam. S420, upper chord and hanging layer adjustment; According to the slope of the truss, the upper chord is hoisted section by section from one end to the other, and the hanging rod is connected to the lower beam with bolts to form a hanging system.

5. The method for hoisting trusses in sections in a confined space according to claim 1, characterized in that: The specific steps of S500 are as follows: S510, stable system construction; S511, quick installation of out-of-plane supports; After the single steel truss is hoisted, the stabilization system is constructed, with priority given to installing simply supported beams and diagonal supports perpendicular to the truss to form a spatially stable frame. S512, simply supported beam connection process; Align one end of the simply supported beam with the node of the upper chord of the truss and insert temporary bolts. Align the other end with the adjacent truss node and also temporarily fix it to ensure that the beam is level. S513, diagonal support stress reinforcement; The diagonal supports and truss nodes are connected by "node plate + welding". After installation, the pre-tension of the diagonal supports is tested with a dynamometer and adjusted with turnbuckle bolts to ensure uniform stress on the support system. S520, temporary support transition; S521, first uninstallation; Lift the shoulder beam with a jack to release the top support force of the lattice column. Use the stress sensor to confirm that the shoulder beam load has been reduced by 50%. Use oxyacetylene to cut the top steel support of the lattice column. After cutting, remove the jack, observe for 1 hour, and record the displacement meter data. S522, second unloading; Repeat the above steps and cut the steel again until the lattice column is completely separated from the shoulder beam and the reaction force of the truss support reaches the design value. During the unloading process, the cutting is carried out synchronously at multiple positions to avoid eccentric force on the support system. After unloading is completed, the lattice column and shoulder beam are removed and the site is cleaned up.

6. The method for hoisting trusses in sections in a confined space according to claim 1, characterized in that: The specific steps of S310 are as follows: S311, positioning of double support points of shoulder pole beam; Mark the positioning lines of GJ-1 and GJ-3 on the shoulder pole beam, verify the coordinates with a total station, place adjustable steel pads at the supports at both ends of the shoulder pole beam, and pre-adjust the elevation to the design value. S312, double-segment spreader synchronization inspection; Prepare two sets of 4-point shoulder pole slings, calculate the lifting point positions according to the center of gravity of GJ-1 and GJ-3, and ensure that the components are level during lifting.

7. The method for hoisting trusses in sections in a confined space according to claim 1, characterized in that: The specific steps for S320 are as follows: S321, GJ-1 hoisting; The tower crane lifts GJ-1 above the shoulder-pole beam and slowly moves it above the left support point. The guy rope is used to control the swing of the component so that the bottom axis is aligned with the shoulder-pole beam positioning line. The left end of the component is temporarily fixed to the shoulder-pole beam with bolts. The right end is connected to the ground anchor with a guy rope to form a unilateral constraint. The deviation of the axis of the left end of the component is measured with a total station, and the elevation is measured with a level. The pad is fine-tuned with a jack until it meets the verticality and elevation requirements. A temporary support steel plate is welded to ensure the stability of the left end. S322, GJ-3 hoisting After GJ-1 is fixed, hoist GJ-3 to the right support point. The process is the same as GJ-1. After the two ends are hoisted in sections, measure the mid-span distance to determine whether the measured value deviates from the theoretical value. If there is a deviation, adjust it through the oblong hole of the GJ-2 interface bolt; S323, double-segment temporary fixation and stabilization; After the two end segments are fixed, both ends of the shoulder beam are subjected to force at the same time. The simply supported beams corresponding to the two end segments are immediately installed and temporarily connected to the truss nodes with high-strength bolts to form a "truss-simply supported beam" out-of-plane stability system.

8. The method for hoisting trusses in sections in a confined space according to claim 1, characterized in that: The specific steps for S330 are as follows: S331, interface preprocessing; Check the dimensions of the GJ-1 and GJ-3 interfaces, and polish the interface steel plates until they are shiny and have a groove angle of 45°. S332, GJ-2 hoisting and docking; Lift GJ-2 with a tower crane to the top of the mid-span, and slowly move it to the interface. First, align it with the GJ-1 interface and install temporary bolts. Then, align it with the GJ-3 interface and install temporary bolts as well. First weld the web plates of the GJ-1 and GJ-2 interfaces, then weld the web plates of the GJ-3 and GJ-2 interfaces, and finally weld the flange plates.

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