A construction method for a large-span rigid entrance porch

Abstract

The invention discloses a construction method of a large-span rigid entrance porch, comprising the following steps: step 1: porch design; step 2: arch foot construction; step 3: arch column installation: 3.1, segmentation and ground assembly: segment the arch column; assemble the adjacent arch columns into larger hoisting units on the ground; 3.2, high-altitude positioning: gradually hoist from both sides to the middle according to the arch column hoisting section and adjust the spatial positioning; 3.3, measurement and design: high-altitude hoisting accurately adjusts the arch column position and position, measures the position coordinates of the arch column pipe mouth, checks the real-time height difference of the arch column to determine whether the arch column is adjusted to the position state; 3.4, high-altitude fixing: after the adjacent hoisting sections are fixed, the connecting beam and tie rod at each arch column are hoisted and fixed; step 4: arch column unloading; step 5: canopy system hoisting; step 6: canopy unloading. The application method is convenient for controlling the installation accuracy of the arch column, improving the convenience of arch column installation, and ensuring the safety and efficiency of construction.

Description

Technical Field

[0001] The invention relates to the technical field of steel structure construction, in particular to a construction method of a large-span rigid entrance porch. Background Art

[0002] The main entrances of densely populated and high-flown places such as airports, stations, stadiums, and convention centers are designed with magnificent shapes, spans of up to hundreds of meters, and beautiful shapes. The design elements of large-span structures have been increasingly applied to engineering design. In order to meet the needs of main entrance use and design, it is generally necessary to reduce the number of supporting structures as much as possible.

[0003] This project is a terminal building of an airport. The roof structure is a large-span steel structure with a plane size of 232m long from east to west, 72m wide from north to south, and 31.9m high. The top elevation of the roof in the east-west direction increases from both ends to the middle, from 19.3m to 31.9m. The main entrance on the south side is designed with inclined arch columns and a canopy system suspended. The canopy system is an orthogonal grid structure with a maximum span of 100 meters, a maximum width of 15 meters, and the highest point is 30.2 meters from the ground. The canopy is supported by hanging on the arch columns.

[0004] Since the roof structure is a wave-shaped structure that is high in the middle and low on both sides, the arch column is designed as an unconventional bending-torsion member to meet the connection requirements with the roof side beams, so as to avoid the connection between the side beams and the arch column at the corner points of the arch column to form a weak point; the hoisting section is an inclined hyperbolic member, and the center of gravity is difficult to determine. There is a possibility of torsional offset during the hoisting process, which has a great impact on the installation accuracy; and the arch column is an exposed member, and the installation accuracy directly affects the visual beauty. How to ensure the installation accuracy, safety and efficiency of the double-torsion member is one of the difficulties faced by this application; the canopy is an orthogonal grid structure with a maximum span of 100 meters, a maximum width of 15 meters, and the highest point is 30.2 meters from the ground. The canopy is suspended and supported on the arch column, and the structural force transmission path is relatively complex; the number of rods shipped from the structure factory is as many as 112, all of which are welded on site, with a high installation height and a poor welding environment; how to ensure the safety of the structure and the installation accuracy during the installation process is the second difficulty faced by this application. Summary of the invention

[0005] The present invention provides a construction method for a large-span rigid entrance porch, which solves the above problems.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The invention discloses a construction method for a large-span rigid entrance porch, comprising the following steps:

[0008] Step 1: Porch design: pre-arch design of arch columns and canopy systems;

[0009] Step 2: Arch foot construction;

[0010] Step 3: Arch column installation:

[0011] 3.1. Segmentation and ground assembly: The arch column is segmented and transported to the site after processing in the factory; a support frame is set up at the segmentation of the arch column on site, and adjacent arch columns are assembled into larger hoisting sections on the ground;

[0012] 3.2. High-altitude positioning: Before installing the lifting section, the temporary adjustable support frame is installed in place, and the arch column is gradually lifted from both sides to the middle. Four lifting ropes are used for lifting and adjusting the spatial positioning; the four lifting ropes are arranged clockwise, namely No. 1 lifting rope, No. 2 lifting rope, No. 3 lifting rope, and No. 4 lifting rope. No. 1 lifting rope has a fixed rope length, and the other three lifting ropes are respectively equipped with hand winches, among which No. 1 and No. 2 lifting ropes are arranged perpendicular to the length of the arch column; after each section of the arch column is separated from the supporting tire frame, it is lifted at high altitude. Two adjustments are performed to ensure spatial positioning efficiency; during the first adjustment, the lengths of No. 1 and No. 2 lifting ropes are kept unchanged, and No. 3 and No. 4 lifting ropes are adjusted. The lifting length of No. 4 lifting rope is adjusted to the designed rope length at one time, and the adjusted length of No. 3 lifting rope is close to or the same as the adjusted length of No. 4 lifting rope, completing the rough adjustment of vertical positioning; during the second adjustment, the lengths of No. 1 and No. 4 lifting ropes are kept unchanged, and the rope lengths of No. 2 and No. 3 lifting ropes are adjusted to the designed position, completing the rough adjustment of the horizontal plane deflection position;

[0013] 3.3. Survey and design: High-altitude hoisting is used to accurately adjust the position of the arch column, measure the position coordinates of the arch column pipe mouth, and check the real-time height difference of the arch column to determine whether the arch column is adjusted to the position;

[0014] 3.4. High-altitude fixing: After the arch column is adjusted into place, the adjusted hoisting section is connected and fixed to the arch foot, and then the connecting beam and tie rod at each section of the arch column are hoisted and fixed. Repeat the above steps to carry out subsequent arch column segment hoisting and installation of connecting beams and tie rods, and finally hoist the closing section to complete the installation of the arch column structure;

[0015] Step 4: Arch column unloading: After all the arch columns are welded, the arch columns are unloaded as a whole. First, the shorter temporary adjustable support frames at both ends of the arch columns are removed, and then the highest temporary adjustable support frame in the middle is removed. Then, the arch columns are unloaded from the middle to both ends at the same time.

[0016] Step 5: Hoisting of the canopy system: hoist and fix the canopy system in sections to the arch columns;

[0017] Step 6: Unloading the awning: After the awning components are welded, first remove the highest temporary adjustable support frame in the middle of the awning, and then unload them from the middle to both ends at the same time.

[0018] The present invention provides a construction method for a large-span rigid entrance porch. Further, in step 3.1, a horizontal line is drawn at the same height at both ends of two hoisting sections on site, and the arc length and arc height are controlled by the length of the horizontal line and the distance between the middle position of the horizontal line and the top elevation of the component. The bottom elevations of the hoisting sections at both ends are controlled to be at the same height by a jack, and the butt spacing, i.e., the line length, of the hoisting sections at both ends is controlled by a hand winch, so as to control the shape accuracy of the hoisting sections assembled into a larger hoisting section.

[0019] The present invention provides a construction method for a large-span rigid entrance porch. Further, in step 3.2, relevant software is used to lay out the arch column hoisting section, accurately determine the center of gravity position of the hoisting section, determine the hoisting point position according to the center of gravity position of the hoisting section, and determine the length of the hoisting rope for each hoisting point in combination with the maximum hoisting height of the crane and the spatial stability of the rope.

[0020] The present invention provides a construction method for a large-span rigid entrance porch. Further, in step 3.2, the arch column is hoisted in sections onto a temporary adjustable support frame on site, a knife plate is provided on the temporary adjustable support frame to adjust the position of the arch column in place, and the next section of the arch column is hoisted in the same manner. After the adjustment of the interface of the two arch columns is completed, the four sides are temporarily fixed with code plates, and welding is performed after the spatial positioning meets the accuracy requirements.

[0021] The present invention provides a construction method for a large-span rigid entrance porch. Further, in step 3.2, the arch column is suspended in mid-air, the construction personnel adjust the position of the arch column, and the on-site surveyor measures the position of the arch column until the arch column is adjusted to the in-place position; when the position is adjusted, the workers need to pull a traction rope on the ground to ensure the stability of the arch column.

[0022] The present invention provides a construction method for a large-span rigid entrance porch. Further, in step 3.3, when there is an error, after the arch column is initially in place, the surveyor measures the arch column pipe mouth coordinates on the ground and compares them with the designed space coordinates to determine the adjustment direction of the arch column. Then, the worker uses a hydraulic jack on the operating platform of a temporary adjustable support frame to adjust the high-altitude position of the arch column. After adjustment, the total station is used to re-measure the arch column pipe mouth coordinates until the arch column is adjusted to the designed state. After completion, the knife plate height is adjusted to support the arch column. After stabilization, the jack is removed and the total station is re-measured.

[0023] The present invention provides a construction method for a large-span rigid entrance porch. Further, in step 4, the overall unloading method is to use flame cutting on site to cut off a knife plate to separate the arch column from the support frame, and then remove the tooling on the top of the support frame; during flame cutting, damage to the arch column is avoided.

[0024] The present invention provides a construction method for a large-span rigid entrance porch. Further, in step 4, a total station monitors the deformation of the arch column throughout the whole process. When the measured data exceeds the numerical analysis limit, the unloading should be stopped immediately, and the unloading can be continued only after the cause is found and the unloading hidden danger is eliminated.

[0025] The present invention provides a construction method for a large-span rigid entrance porch. Further, in step 5, the canopy system is divided into a plurality of "L"-shaped hoisting units, connecting rods between the units and a plurality of sections of edge beams, and temporary adjustable support frames are arranged at the sections of the edge beams. The first section of the edge beams is installed first, and then the "L"-shaped hoisting units are assembled on the ground and hoisted into place, and the connecting rods and pull rods between the hoisting "L"-shaped hoisting units are installed. The above steps are repeated until the entire canopy system is completed, and finally the temporary adjustable support frames are removed.

[0026] The invention discloses a construction method for a large-span rigid entrance porch. Further, a crawler crane is used to hoist the edge beam of the canopy, and the "L"-shaped hoisting unit, connecting rods and pull rods are continuously hoisted inside the canopy system. After the hoisting of the heavier "L"-shaped hoisting unit in the middle span is completed, the crawler is hoisted to the outside of the canopy system to continue the hoisting of subsequent rods.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The hoisting section of the arch column is an inclined hyperbolic component, the center of gravity is difficult to determine, there is a possibility of torsion offset during the hoisting process, the installation is difficult, and the accuracy is difficult to ensure. This application uses AUTOCAD and other related software to lay out the arch column hoisting section, accurately determine the center of gravity position of the component, and determine the component hanging point and the length of the hanging rope at each hanging point according to the center of gravity of the component. Then, four hanging ropes are used to use high-altitude adjustment to adjust the arch column to the position of the arch column installation state, and then the arch column is installed in place, which is convenient for controlling the installation accuracy of the arch column and improving the installation convenience of the arch column;

[0029] 2. Through the specific adjustment method of four lifting ropes, the arch column can be quickly adjusted to the position at high altitude, which is more convenient to operate and suitable for the lifting construction of hyperbolic components;

[0030] 3. In view of the problem that the arch column components are divided into many sections and have large cross-sections, which makes it difficult to weld them at high altitude, this application connects the arch columns two by two as one section on the ground for hoisting, thus reducing the work of high-altitude docking;

[0031] 4. In view of the problems that the canopy system has many rods, high installation height and poor welding environment, this application divides the canopy system into several "L"-shaped lifting units, connecting rods between units and multiple sections of edge beams. The edge beams are installed first, then the "L"-shaped lifting units are lifted and fixed, and finally the connecting rods are embedded, which reduces high-altitude welding work and ensures the installation accuracy of the canopy system and the safety of construction.

[0032] The present invention will be further described below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of the present invention;

[0034] Figure 2 This is a schematic diagram of the segmented high-altitude position adjustment of the arch column of the present invention;

[0035] Figure 3 This is a schematic diagram of the structure of the first section of the arch column of the present invention after installation;

[0036] Figure 4 This is a schematic diagram of the structure of the closed section of the arch column of the present invention after installation;

[0037] Figure 5 This is a schematic diagram of the structure of the canopy system of the present invention;

[0038] Figure 6 This is a schematic diagram of the canopy hoisting system inside the crane of the present invention;

[0039] Figure 7 This is a schematic diagram of the hoisting structure of the "L"-shaped hoisting unit of the present invention;

[0040] Figure 8 It is a schematic diagram of the installation structure of the "L"-shaped hanging unit of the present invention.

[0041] Reference numerals:

[0042] 1. Arch foot; 2. Arch column; 3. Connecting beam; 4. Tie rod; 5. Canopy system; 5.1. Vertical member; 5.2. Horizontal member; 5.3. Connecting rod; 5.4. Pull rod; 5.5. Edge beam; 6. Roof structure; 7. Edge beam; 8. Supporting horse stool; 9. Temporary adjustable support frame; 10. No. 1 lifting rope; 11. No. 2 lifting rope; 12. No. 3 lifting rope; 13. No. 4 lifting rope. DETAILED DESCRIPTION

[0043] like Figure 1-Figure 8As shown, the present invention discloses a construction method of a large-span rigid entrance porch, the entrance porch comprises an arch foot 1, an arch column 2, a connecting beam 3, a tie rod 4 and a canopy system 5, the arch foot 1 is arranged at both ends close to the entrance side of the structure, and comprises a pile foundation, a reinforced concrete pedestal arranged on the pile foundation and a steel column with one end inserted into the reinforced concrete pedestal; the two ends of the arch column 2 are respectively welded and fixed to the steel column on the arch foot 1, the arch column 2 is arranged gradually close to the roof structure 6 side from the two ends to the middle along the horizontal direction, the connecting beam 3 is connected and fixed between the arch column 2 and the side beam 7 of the roof structure 6, the connecting beam 3 is arranged at intervals in a plurality of rows along the length direction of the arch column 2, the tie rods 4 are connected between the connecting beams 3, and the tie rods 4 are arranged at intervals in a plurality of rows along the length direction of the connecting beam 3; the canopy system 5 is hung on the arch column 2. The arch column 2 is symmetrically arranged with its center as the axis, and the arch column 2 is connected by multiple sections of bending-torsion components that are alternately arranged with positive torsion and reverse torsion with its center as the axis. By designing the arch column 2 as an unconventional bending-torsion component, the connection requirements between the arch column 2 and the side beam 7 are met, and the connection between the side beam 7 and the arch column 2 is avoided at the corner point of the arch column 2, thereby ensuring the safety of the structure.

[0044] The canopy system 5 includes a vertical member 5.1, a horizontal member 5.2, a connecting rod 5.3, a pull rod 5.4 and an edge beam 5.5. The vertical members 5.1 are fixedly arranged on the bottom surface of the arch column 2 at intervals. One end of the horizontal member 5.2 is fixedly connected to the lower end of the vertical member 5.1, and the other end is fixedly connected to the edge beam 5.5; both ends of the edge beam 5.5 are respectively fixedly connected to the arch column 2; the connecting rod 5.3 is respectively connected between the vertical members 5.1 and the horizontal members 5.2; one end of the pull rod 5.4 is connected to the arch column 2, and the other end is connected to the horizontal member 5.2.

[0045] The construction method includes the following steps:

[0046] Step 1; Porch design: The maximum span of the arch column 2 in this application is 165m, and the maximum span of the canopy is 100m. After the structure is installed, each component will have different degrees of deflection. In order to ensure the installation of the building appearance and the enclosure structure, the arch column 2 and the canopy are pre-arched. The steel structure is deepened and modeled and drawn according to the arch value required by the design drawings, and the components are processed according to the drawings after arching.

[0047] Step 2: Arch foot construction:

[0048] First, the pile foundation is constructed by chiseling and clearing the pile head, and then the steel skeleton of the reinforced concrete cap is tied and the steel column is pre-buried, and the horse stool 8 is supported at the end of the steel column and inside the column foot. After completion, the formwork is erected to pour concrete and backfill the earth.

[0049] Step 3: Arch column installation:

[0050] Since the arch column 2 is a symmetrical structure about the central axis, the arch column 2 is symmetrically divided into sections on the left and right sides. The arch column 2 components are processed in the factory and transported to the site. A support frame is set at the arch column 2 section on site, and the two sections are assembled into a larger lifting section on the ground. Specifically, a horizontal line is drawn at the same height at both ends of the two lifting sections on site. The arc length and arc height of the lifting section are controlled by the length of the horizontal line and the distance from the middle position of the horizontal line to the top elevation of the component. The bottom elevation of the lifting sections at both ends is controlled at the same height by the jack, and the hand chain hoist controls the docking distance of the lifting sections at both ends, that is, the line length, so as to control the shape accuracy of the two lifting sections assembled into a larger lifting section. The arch column 2 lifting section is laid out using AUTOCAD software to accurately determine the center of gravity position of the lifting section, and the lifting point position is determined according to the center of gravity position of the lifting section, and the length of the lifting rope for each lifting point is determined in combination with the maximum lifting height of the crane and the spatial stability of the rope.

[0051] The arch column 2 is hoisted with four lifting points located on both sides of the arch column 2. The arch column 2 is an unconventional double-torsion member. Before hoisting, it is necessary to accurately lay out and determine the center of gravity of each unit, so as to select a suitable length of lifting rope to ensure that the hook lifting point and the center of gravity of the unit are located on the same vertical line to ensure that the structure can maintain a certain aerial posture. The lifting position is controlled at one-fourth of the length of the arch column 2 as much as possible, and a hand winch is used to adjust the high-altitude position of the arch column 2 during hoisting.

[0052] The arch column 2 is hoisted from both sides to the middle by a crawler crane. Temporary adjustable support frames 9 are set at each section. Finally, the closing section is hoisted to complete the hoisting of the arch column 2 structure. Since the arch column 2 is a two-way bending in space, the contact surface between each temporary adjustable support frame 9 and the arch column 2 is different. Accurate lofting is required before installation. A support that conforms to the shape of the arch column 2 is installed on the top of the temporary adjustable support frame 9 to ensure the accuracy and stability of the installation of the arch column 2. An operating platform is also installed on the top of the temporary adjustable support frame 9. The docking work of the arch column 2 sections is completed manually on the operating platform. After the arch column 2 is hoisted and fixed, the connecting beam 3 and tie rod 4 on the section are installed to reduce the horizontal force of the temporary adjustable support frame 9 under wind load and improve the overall construction safety. After each section of the arch column 2 is installed in place, positioning measurement is carried out, and the components with deviations in the installation are adjusted in time to ensure that they are ready for installation. Then the installation of the arch column 2 on the other side is completed in the same way, and finally the closing section of the arch column 2 is hoisted and the temporary adjustable support frame 9 is removed.

[0053] Specifically, a flatbed truck is used to transport the arch column 2 in sections to the support frame, and a truck crane is used to hoist the arch column 2 in sections onto the support frame. A knife plate is set on the support frame to adjust the position of the arch column 2. The next section of the arch column 2 is hoisted in the same way. After the adjustment of the interface of the two arch columns 2 is completed, the four sides are temporarily fixed with code plates. After the spatial positioning meets the accuracy requirements, welding is carried out. Symmetrical synchronous welding is adopted. Two welders perform vertical welding on the left and right sides at the same time. After welding, magnetic powder and ultrasonic flaw detection are carried out. After the welding of the welds on both sides is completed, one worker welds above the arch column 2 and the other welds below the arch column 2 at the same time. After welding, flaw detection is carried out.

[0054] After all welds are inspected, a crawler crane is used for hoisting. Arch column 2 is hoisted in mid-air. A person on a lifting vehicle is used to adjust the position of arch column 2. On-site surveyors measure the position of arch column 2 until arch column 2 is adjusted to the position. At the same time, workers need to pull traction ropes on the ground to ensure the stability of arch column 2. Four hoisting ropes are used for hoisting. The four hoisting ropes are arranged clockwise as No. 1 hoisting rope 10, No. 2 hoisting rope 11, No. 3 hoisting rope 12, and No. 4 hoisting rope 13. Among them, No. 1 hoisting rope 10 is a fixed rope length, and the other three hoisting ropes are respectively equipped with hand winches. No. 1 hoisting rope and No. 2 hoisting rope are arranged perpendicular to the length of the arch column. After each section of the arch column 2 is separated from the supporting frame, when the rope length is adjusted for the first time, the lengths of No. 1 lifting rope 10 and No. 2 lifting rope 11 remain unchanged, and No. 3 lifting rope 12 and No. 4 lifting rope 13 are adjusted, and the lifting length of No. 4 lifting rope 13 is once set to the designed rope length, and the adjusted length of No. 3 lifting rope 12 is similar to or the same as the adjusted length of No. 4 lifting rope 13; a rough adjustment of the vertical positioning is completed; and then a second adjustment is performed. The second adjustment directly adjusts the arch column 2 to the designed position, keeping No. 1 lifting rope 10 and No. 4 lifting rope 13 unchanged, and adjusting the rope lengths of No. 2 lifting rope 11 and No. 3 lifting rope 12 to the designed position, completing a rough adjustment of the horizontal plane deflection position.

[0055] The arch column 2 is hoisted into place, and at the same time, the surveyor uses a total station on the ground to monitor the high-altitude position of the arch column 2. A tool is set on the top of the temporary adjustable support frame 9 to adjust the position of the arch column 2. The hook can be released after the measurement result is passed.

[0056] Specifically, a reflective sheet is attached to the pipe opening of the arch column 2 in advance. After the rope length of the arch column 2 is adjusted, a surveyor is arranged to measure the coordinates of the reflective sheet with a total station on the ground, and the real-time height difference of the arch column 2 is checked on site to determine whether the arch column 2 is adjusted to the position.

[0057] When there is an error, after the arch column 2 is initially in place, the surveyor measures the pipe mouth coordinates of the arch column 2 on the ground and compares them with the designed space coordinates to determine the adjustment direction of the arch column 2. Then the workers use the hydraulic jack on the operating platform of the temporary adjustable support frame 9 to adjust the high-altitude position of the arch column 2. After adjustment, the total station is used to re-measure the pipe mouth coordinates of the arch column 2 until the arch column 2 is adjusted to the designed state. After completion, the knife plate height is adjusted to support the arch column 2. After stabilization, the jack is removed and the total station is re-measured.

[0058] After the arch column 2 is hoisted into place, in order to ensure the lateral stability of the arch column 2, a crawler crane is used to hoist the connecting beam 3 and the tie rod 4 for fixing the arch column 2, and workers perform welding operations on a crane.

[0059] Repeat the above process to carry out subsequent segmented hoisting of the arch column 2, and the installation of the connecting beam 3 and the tie rod 4 can be carried out in a conventional manner.

[0060] Step 4: Unloading:

[0061] After all the welding of the arch column 2 is completed and accepted, the arch column 2 forms a whole, and the arch column 2 is unloaded as a whole. The unloading steps are as follows: first, the shorter temporary adjustable support frames 9 at both ends are removed, and then the highest temporary adjustable support frame 9 in the middle is removed, and then the two are unloaded from the middle to both ends at the same time. The overall unloading method is to use flame cutting on site to cut off the knife plate to separate the arch column 2 from the temporary adjustable support frame 9, and then remove the tooling on the top of the temporary adjustable support frame 9; during flame cutting, the loss of the arch column is avoided; when the arch column is unloaded, the total station is used to monitor the deformation of the arch column throughout the process. When the measured data exceeds the numerical analysis limit, the unloading should be stopped immediately, and the unloading can be continued only after the cause is found and the unloading hidden danger is removed.

[0062] Step 5: Sectioning and installation of canopy:

[0063] Since the canopy has a vertical rod structure, it is difficult to install the canopy when the arch column 2 has been installed in place. Therefore, the canopy system 5 is divided into a number of "L"-shaped lifting units, connecting rods 5.3 between units and multiple sections of edge beams 5.5. The "L"-shaped lifting unit is hoisted as a whole after being assembled on the ground. After the lifting of two adjacent lifting units is completed, the connecting rods 5.3 between the units are filled; temporary adjustable support frames 9 are set at the sections of the edge beams 5.5.

[0064] Specifically, a crawler crane is used to install the first section of the edge beam 5.5 of the canopy system 5, the "L"-shaped lifting unit is assembled on the ground and lifted into place, and the connecting rod 5.3 and the pull rod 5.4 between the "L"-shaped lifting units are installed. Due to the lifting limit of the crane, the crawler is lifted to the inside of the canopy system 5 for lifting. Repeat the above process, use the crawler crane to lift the canopy edge beam 5.5 inside the canopy system 5, and continue to lift the "L"-shaped lifting unit, connecting rod 5.3 and pull rod 5.4 inside the canopy system 5. After completing the lifting of the heavier L"-shaped lifting unit in the middle span, lift the crawler to the outside of the canopy system 5, continue to lift the subsequent rods, and finally remove the temporary adjustable support frame 9 to complete the installation of the canopy system 5.

[0065] Among them, since the "L"-shaped lifting unit is an unconventional component, it is necessary to accurately lay out and determine the center of gravity of each unit before lifting, so as to select a lifting rope of appropriate length, ensure that the hook lifting point and the center of gravity of the lifting unit are on the same vertical line, and ensure that the structure can maintain a certain aerial posture. The "L"-shaped lifting unit can be directly lifted at the installation angle to reduce the difficulty of adjustment after lifting into place.

[0066] Step 6: Unloading of the canopy: After the canopy components are welded, first remove the highest temporary adjustable support frame in the middle of the canopy system 5, and then unload them from the middle to both ends simultaneously.

[0067] The embodiments described above are merely descriptions of preferred implementation modes of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A construction method for a large-span rigid entrance porch, characterized in that: The following steps are involved: Step 1: Porch design: pre-arch design of arch columns and canopy systems; Step 2: Arch foot construction; Step 3: Arch column installation: 3.

1. Segmentation and ground assembly: The arch column is segmented and transported to the site after processing in the factory; a support frame is set up at the segmentation of the arch column on site, and adjacent arch columns are assembled into larger hoisting sections on the ground; 3.

2. High-altitude positioning: Before installing the lifting section, the temporary adjustable support frame is installed in place, and the arch column is gradually lifted from both sides to the middle. Four lifting ropes are used for lifting and adjusting the spatial positioning; the four lifting ropes are arranged clockwise, namely No. 1 lifting rope, No. 2 lifting rope, No. 3 lifting rope, and No. 4 lifting rope. No. 1 lifting rope has a fixed rope length, and the other three lifting ropes are respectively equipped with hand winches, among which No. 1 and No. 2 lifting ropes are arranged perpendicular to the length of the arch column; after each section of the arch column is separated from the supporting tire frame, it is lifted at high altitude. Two adjustments are performed to ensure spatial positioning efficiency; during the first adjustment, the lengths of No. 1 and No. 2 lifting ropes are kept unchanged, and No. 3 and No. 4 lifting ropes are adjusted. The lifting length of No. 4 lifting rope is adjusted to the designed rope length at one time, and the adjusted length of No. 3 lifting rope is close to or the same as the adjusted length of No. 4 lifting rope, completing the rough adjustment of vertical positioning; during the second adjustment, the lengths of No. 1 and No. 4 lifting ropes are kept unchanged, and the rope lengths of No. 2 and No. 3 lifting ropes are adjusted to the designed position, completing the rough adjustment of the horizontal plane deflection position; 3.

3. Survey and design: High-altitude hoisting is used to accurately adjust the position of the arch column, measure the position coordinates of the arch column pipe mouth, and check the real-time height difference of the arch column to determine whether the arch column is adjusted to the position; 3.

4. High-altitude fixing: After the arch column is adjusted into place, the adjusted hoisting section is connected and fixed to the arch foot, and then the connecting beam and tie rod at each section of the arch column are hoisted and fixed. Repeat the above steps to carry out subsequent arch column segment hoisting and installation of connecting beams and tie rods, and finally hoist the closing section to complete the installation of the arch column structure; Step 4: Arch column unloading: After all the arch columns are welded, the arch columns are unloaded as a whole. First, the shorter temporary adjustable support frames at both ends of the arch columns are removed, and then the highest temporary adjustable support frame in the middle is removed. Then, the arch columns are unloaded from the middle to both ends at the same time. Step 5: Hoisting of the canopy system: hoist and fix the canopy system in sections to the arch columns; Step 6: Unloading the awning: After the awning components are welded, first remove the highest temporary adjustable support frame in the middle of the awning, and then unload them from the middle to both ends at the same time.

2. The construction method of a large-span rigid entrance porch according to claim 1, characterized in that: In step 3.1, a horizontal line is drawn at the same height at both ends of the two lifting sections on site. The arc length and arc height are controlled by the length of the horizontal line and the distance from the middle position of the horizontal line to the top elevation of the component. The bottom elevations of the lifting sections at both ends are controlled at the same height by the jack. The hand chain hoist controls the docking distance of the lifting sections at both ends, that is, the line length, so as to control the shape accuracy of the lifting sections assembled into a larger lifting section.

3. The construction method of a large-span rigid entrance porch according to claim 1, characterized in that: In step 3.2, relevant software is used to lay out the arch column hoisting section, accurately determine the center of gravity of the hoisting section, and determine the position of the lifting point based on the center of gravity of the hoisting section. In addition, the length of the lifting rope for each lifting point is determined in combination with the maximum lifting height of the crane and the spatial stability of the rope.

4. The construction method of a large-span rigid entrance porch according to claim 1, characterized in that: In step 3.2, the arch column is hoisted in sections to a temporary adjustable support frame on site. A knife plate is set on the temporary adjustable support frame to adjust the arch column's position. The next section of the arch column is hoisted in the same way. After the two arch column segment interfaces are adjusted, they are temporarily fixed on all four sides with code plates. Welding is performed after the spatial positioning meets the accuracy requirements.

5. The construction method of a large-span rigid entrance porch according to claim 1, characterized in that: In step 3.2, the arch column is suspended in the air, and the construction workers adjust the position of the arch column. The on-site surveyor measures the position of the arch column until the arch column is adjusted to the position. When adjusting the position, the workers need to pull a traction rope on the ground to ensure the stability of the arch column.

6. The construction method of a large-span rigid entrance porch according to claim 1, characterized in that: In step 3.3, when there is an error, after the arch column is initially in place, the surveyor measures the arch column pipe mouth coordinates on the ground and compares them with the designed space coordinates to determine the adjustment direction of the arch column. Then the worker uses a hydraulic jack on the operating platform of the temporary adjustable support frame to adjust the high-altitude position of the arch column. After adjustment, the total station is used to re-measure the arch column pipe mouth coordinates until the arch column is adjusted to the designed state. After completion, the knife plate height is adjusted to support the arch column. After stabilization, the jack is removed and the total station is re-measured.

7. The construction method of a large-span rigid entrance porch according to claim 1, characterized in that: In step 4, the overall unloading method is to use flame cutting on site to cut off the blade to separate the arch column from the support frame, and then remove the tooling on the top of the support frame; when flame cutting, avoid damaging the arch column.

8. The construction method of a large-span rigid entrance porch according to claim 1, characterized in that: In step 4, the total station monitors the deformation of the arch column throughout the process. When the measured data exceeds the numerical analysis limit, the unloading should be stopped immediately, and the unloading can be continued only after the cause is found and the unloading hidden danger is eliminated.

9. The construction method of a large-span rigid entrance porch according to claim 1, characterized in that: In step 5, the canopy system is divided into several "L"-shaped lifting units, connecting rods between units and multiple sections of edge beams. Temporary adjustable support frames are set at the sections of the edge beams. The first section of the edge beam is installed first, and then the "L"-shaped lifting unit is assembled on the ground and hoisted into place. The connecting rods and pull rods between the "L"-shaped lifting units are installed. Repeat the above steps until the entire canopy system is completed, and finally remove the temporary adjustable support frame.

10. The construction method of a large-span rigid entrance porch according to claim 7, characterized in that: Use crawler crane to hoist the canopy edge beam, and continue to hoist the "L"-shaped hoisting unit, connecting rod and pull rod inside the canopy system. After completing the hoisting of the heavier "L"-shaped hoisting unit in the middle span, open the crawler to the outside of the canopy system and continue to hoist the subsequent rods.

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