A gravity center pre-matching segmentation method for arc-shaped steel truss

Abstract

This invention discloses a method for pre-matching the center of gravity of an arc-shaped steel truss, comprising: dividing the arc-shaped steel truss into inner steel beams, a middle truss, and an outer cantilever structure; defining the top sides and connecting structures of the middle truss as pre-installed sections for pre-assembly; selecting post-installed members based on the center of gravity offset and eccentricity of the arc-shaped steel truss, defining a portion of the upper chord of the outer cantilever structure as a post-installed section; defining the remaining structure as a lifting section; assembling the lifting section on the ground, and using the post-installed section as a temporary counterweight. This invention divides the arc-shaped steel truss into pre-installed, lifting, and post-installed sections by matching the center of gravity, and uses the post-installed section as a temporary counterweight on the assembled lifting section. This minimizes the deviation between the center of gravity of the lifting section and the centroid of the lifting point, and simplifies the lifting process. By optimizing the construction segmentation, it solves the problem of eccentric lifting of arc-shaped trusses, avoiding the need for asymmetrical lifting points or adding a large amount of counterweight, and has the advantages of simple construction and high reliability.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a method for pre-matching and segmenting the center of gravity of an arc-shaped steel truss. Background Technology

[0002] In the field of steel structure construction, there exists a special type of cantilevered arc-shaped steel truss structure. This type of truss connects to the main structure only on one side, making symmetrical lifting on both sides impossible. Furthermore, its arc shape causes an off-center center of gravity, posing numerous technical challenges to on-site installation. Currently, the industry commonly employs high-altitude assembly for this type of single-sided, asymmetrical, and off-center cantilevered arc-shaped steel truss. However, high-altitude assembly of individual components has significant drawbacks: it involves a large workload for high-altitude assembly and welding, requires high hoisting precision, and has low operational efficiency. Simultaneously, high-altitude assembly requires the erection of numerous scaffolding frames, and the safety of these frames is difficult to guarantee due to limitations in construction space and the high-altitude working environment.

[0003] In existing technologies, some construction schemes for cantilevered curved steel trusses employ the method of erecting temporary hoisting equipment to hoist the steel truss as a whole. However, due to the relatively off-center center of gravity of the curved steel truss, it is difficult to accurately analyze the hoisting points. During the hoisting process, external factors can easily cause the center of gravity to deviate from the hoisting points, resulting in poor hoisting stability and significant safety hazards, making it difficult to meet the requirements of safe and efficient construction.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] To address the problem that existing technologies using temporary hoisting equipment to hoist steel trusses as a whole present significant safety hazards due to the off-center center of gravity of curved steel trusses, making precise analysis of the hoisting points difficult and causing the center of gravity to deviate from the hoisting points easily due to external factors, this invention provides a pre-matching segmentation method for the center of gravity of curved steel trusses.

[0006] This invention is achieved through the following technical solution: A method for pre-matching the center of gravity of a curved steel truss, wherein the method includes: A cantilevered support is provided, the cantilevered support including several suspension points; Based on structural characteristics, the arc-shaped steel truss is divided into inner steel beams, middle truss, and outer cantilever structure; The top sides and connecting structures of the central truss are defined as pre-installed sections, which are pre-installed on the permanent structure on one side of the building. Based on the center of gravity offset and eccentricity of the arc-shaped steel truss, the post-installed members are selected, and the post-installed members and part of the upper chord in the external cantilever structure are defined as post-installed sections; the inner steel beam, the remaining middle truss, and the remaining external cantilever structure are defined as lifting sections; The lifting section is assembled on the ground, and the post-installed section is installed on the lifting section as a temporary counterweight, so that the center of gravity of the lifting section is nearly coincident with the centroid of the lifting point.

[0007] The aforementioned method for pre-matching the center of gravity of an arc-shaped steel truss includes the provision of cantilever supports, which comprise several suspension points including: Two cantilever supports are installed on the permanent structure on one side of the building. The two cantilever supports are mirror images of each other at a predetermined angle, and the suspension points of the two cantilever supports are the same.

[0008] The aforementioned method for pre-matching the center of gravity of an arc-shaped steel truss, wherein the process of assembling the lifting section on the ground and installing the post-installed section as a temporary counterweight on the lifting section, so that the center of gravity of the lifting section is nearly coincident with the centroid of the lifting point, further includes: The lifting section is raised to the design elevation through the lifting points of the two cantilever brackets, and the lifting section and the pre-assembled section are connected. Disassemble the rear section and install it at the designed position of the lifting section.

[0009] The aforementioned method for pre-matching the center of gravity of an arc-shaped steel truss, wherein selecting post-installed members based on the center of gravity offset and eccentricity of the arc-shaped steel truss includes: Obtain the overall mass distribution of the curved steel truss and determine the original center of gravity position and eccentricity; Identify multiple members in the arc-shaped steel truss that are opposite to the direction in which the center of gravity is biased to one side, and calculate the moments of the multiple members; The member with the largest torque is selected as the post-installed member.

[0010] The aforementioned method for pre-matching the center of gravity of an arc-shaped steel truss, wherein selecting the member with the largest moment as the post-installed member includes: When there are members with equal torque contributions, the member on the outer side of the arc that is far from the lifting point is selected, or the member with fewer nodes and easier assembly and disassembly is selected.

[0011] The aforementioned method for pre-matching the center of gravity of an arc-shaped steel truss segmentation, wherein the post-installed member is a single member or a combination of members at multiple different positions.

[0012] The aforementioned method for pre-matching the center of gravity of an arc-shaped steel truss, wherein the formula for calculating the moment of the member is: Mi =G i *L i *sinθ i ; Among them, M i G is the torque of the rod. i For the weight of the rod, L i θ is the horizontal distance from the center of gravity of the member to the centroid of the lifting point. i It is the angle between the line connecting the center of gravity of the member and the centroid of the suspension point and the horizontal plane.

[0013] The aforementioned method for pre-matching the center of gravity of curved steel trusses, wherein the total moment contribution ∑M of the post-installed segment... i The eccentric torque M of the lifting section e Within the predetermined threshold deviation and in the opposite direction; The eccentric torque M of the lifting section e The calculation formula is: M e =G 总 ×e; Among them, G 总 denoted as the total weight of the truss, and e as the eccentricity between the original center of gravity and the centroid of the suspension point.

[0014] The aforementioned method for pre-matching the center of gravity of an arc-shaped steel truss, wherein installing the post-installed section as a temporary counterweight on the lifting section includes: Several temporary reinforcing members are installed on the lifting section, and the temporary reinforcing members are fixedly connected to the middle truss. The post-installed section is fixed to the nodes of several of the temporary reinforcing members.

[0015] The aforementioned method for pre-matching the center of gravity of an arc-shaped steel truss includes a temporary reinforcing member made of Hw200×200 steel, and a post-installed section fixed at a quarter node of the member.

[0016] The beneficial effects of this invention are as follows: This invention divides the arc-shaped steel truss into a pre-assembly section, a lifting section, and a post-assembly section by matching the center of gravity. The post-assembly section is installed as a temporary counterweight on the lifting section after it is assembled on the ground. On the one hand, this minimizes the deviation between the center of gravity of the lifting section and the centroid of the lifting point. On the other hand, it simplifies the lifting process. Without changing the symmetry of the support and the lifting point, the eccentric lifting problem of the arc-shaped truss is solved by optimizing the construction segmentation. This avoids setting asymmetrical lifting points or adding a large amount of counterweight. It has the advantages of reducing the influence of external factors on the lifting process, simple construction, and safety and reliability. Attached Figure Description

[0017] Figure 1 This is a flowchart of the pre-matching segmentation method for the center of gravity of an arc-shaped steel truss according to the present invention; Figure 2This is a schematic diagram of the structural division of the arc-shaped steel truss in the pre-matching segmentation method for the center of gravity of the arc-shaped steel truss of the present invention; Figure 3 This is a schematic diagram of the pre-assembled segment in the pre-matching segmentation method for the center of gravity of an arc-shaped steel truss according to the present invention; Figure 4 This is a schematic diagram of the installation of the lifting section, the post-installation section, and the temporary reinforcing members in the pre-matching segmentation method for the center of gravity of the arc-shaped steel truss of the present invention.

[0018] exist Figures 1 to 4 In the middle section: 10. Arc-shaped steel truss; 11. Inner steel beam; 12. Middle truss; 13. Outer cantilever structure; 20. Pre-assembled section; 30. Lifting section; 40. Post-assembled section; 50. Temporary reinforcing members. Detailed Implementation

[0019] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] In existing technologies, some construction schemes for cantilevered curved steel trusses employ the method of erecting temporary hoisting equipment to hoist the steel truss as a whole. However, due to the relatively off-center center of gravity of the curved steel truss, it is difficult to accurately analyze the hoisting points. During the hoisting process, external factors can easily cause the center of gravity to deviate from the hoisting points, resulting in poor hoisting stability and significant safety hazards, making it difficult to meet the requirements of safe and efficient construction.

[0023] To address the aforementioned problems in the prior art, this invention provides a method for pre-matching the center of gravity of curved steel trusses in segmentation, such as... Figure 1 As shown, the pre-matching segmentation method for the center of gravity of an arc-shaped steel truss includes: S100. A cantilevered support is provided, wherein the cantilevered support includes several suspension points; S200. Based on structural characteristics, the arc-shaped steel truss is divided into inner steel beams, middle truss and outer cantilever structure. S300, The tops on both sides of the central truss and the connecting structure are defined as pre-installed sections, which are pre-installed on the permanent structure on one side of the building; S400. Select post-installed members based on the center of gravity offset and eccentricity of the arc-shaped steel truss, and define the post-installed members and part of the upper chord in the external cantilever structure as post-installed sections; define the inner steel beam, the remaining middle truss, and the remaining external cantilever structure as lifting sections; S500. Assemble the lifting section on the ground and install the post-installed section as a temporary counterweight on the lifting section so that the center of gravity of the lifting section is close to the centroid of the lifting point.

[0024] In this embodiment, a cantilever support is pre-installed at a predetermined height position on the building. The cantilever support includes several lifting points, which are used to determine the centroid of the lifting points and the subsequent hoisting operation of the lifting section.

[0025] Next, as Figure 2 As shown, based on the structural characteristics of the arc-shaped steel truss 10, it is decomposed into three main parts: inner steel beam 11, middle truss 12, and outer cantilever structure 13. Among them, the inner steel beam 11 is usually the part close to the main structure of the building, the middle truss 12 is the core load-bearing part connecting the inner steel beam 11 and the outer cantilever structure 13, and the outer cantilever structure 13 is the arc-shaped part that extends outward.

[0026] Then, as Figure 3 As shown, the top of both sides of the central truss 12 and the related connecting structures are set as pre-installed sections 20. Before the hoisting and lifting sections are installed, these structures are pre-installed and fixed on the permanent structure on one side of the building to provide a stable foundation and connection point for the subsequent docking of the lifting sections.

[0027] The next crucial step is to select suitable post-installed members based on the overall center of gravity offset of the curved steel truss 10 and the calculated eccentricity, such as... Figure 4 As shown, these post-installed members together with part of the upper chord in the outer cantilever structure 13 constitute the post-installed section; correspondingly, the inner steel beam 11, the remaining middle truss 12 except for the pre-installed section 20, and the remaining outer cantilever structure 13 except for the part involved in the post-installed section 40 together constitute the lifting section 30.

[0028] Finally, as Figure 4 As shown, the lifting section is assembled on the ground, and the post-installed section 40 is installed on the lifting section 30 as a temporary counterweight. In this way, the overall center of gravity of the lifting section 30 is adjusted so that it is as close as possible to the centroid of the lifting point on the cantilever support, thereby creating favorable conditions for subsequent safe and stable lifting.

[0029] This invention divides the arc-shaped steel truss into a pre-assembly section, a lifting section, and a post-assembly section by matching the center of gravity. The post-assembly section is installed as a temporary counterweight on the lifting section after it is assembled on the ground. On the one hand, this minimizes the deviation between the center of gravity of the lifting section and the centroid of the lifting point. On the other hand, it simplifies the lifting process. Without changing the symmetry of the support and the lifting point, the eccentric lifting problem of the arc-shaped truss is solved by optimizing the construction segmentation. This avoids setting asymmetrical lifting points or adding a large amount of counterweight. It has the advantages of reducing the impact of external factors on the lifting process, simple construction, and safety and reliability.

[0030] Furthermore, the aforementioned cantilever support includes several suspension points, including: S110. Two cantilever supports are installed on the permanent structure on one side of the building. The two cantilever supports are mirror images of each other at a predetermined angle, and the suspension points of the two cantilever supports are the same.

[0031] In this embodiment, two cantilever supports are specifically set on the permanent structure on one side of the building. These two cantilever supports are temporary structures. After the construction is completed, the cantilever lifting supports at the single-side support point can be disassembled as a whole and transported to the next construction section for reuse, thereby reducing project costs. The two cantilever supports are mirrored at a predetermined angle to ensure that the two cantilever supports form a symmetrical force system in space, thereby providing a stable support foundation for the subsequent hoisting of the lifting section.

[0032] Meanwhile, to ensure that the lifting section is evenly stressed and lifted smoothly during the hoisting process, the number, position, and load-bearing parameters of the lifting points on the two cantilever supports are kept the same. This allows each lifting point to evenly distribute the weight of the lifting section and prevents the lifting section from tilting or twisting during hoisting due to differences in the placement of the lifting points. In one specific embodiment, each cantilever support preferably has two lifting points, spaced a certain distance apart.

[0033] Furthermore, the process of assembling the lifting section on the ground and installing the post-installed section as a temporary counterweight on the lifting section, so that the center of gravity of the lifting section is nearly coincident with the centroid of the lifting point, further includes: S610. The lifting section is lifted to the design elevation through the lifting points of the two cantilever brackets, and the lifting section and the pre-assembled section are connected. S620. Disassemble the rear section and install the rear section at the designed position of the lifting section.

[0034] In this embodiment, after the temporary counterweights for the lifting section and the rear section are installed and the center of gravity of the lifting section is nearly coincident with the centroid of the lifting point, the lifting operation can be started.

[0035] By controlling the synchronous movement of the lifting points on the two cantilever supports, the hoisting equipment slowly and steadily lifts the entire lifting section to the preset design elevation. During this process, since the center of gravity of the lifting section has been adjusted to be close to the centroid of the lifting point through the temporary counterweight of the rear section, the stability of the lifting section during the ascent can be effectively guaranteed, reducing swaying and tilting.

[0036] Once the lifting section is accurately positioned, construction workers precisely align and rigidly connect it with the pre-installed section pre-installed on the permanent structure on one side of the building. This is achieved through methods such as high-strength bolts or welding, ensuring that the two form a stable whole. After the lifting section and the pre-installed section are firmly connected, the post-installed section, which serves as a temporary counterweight, can be removed from the lifting section. Subsequently, according to the design drawings of the curved steel truss, the removed post-installed section is moved to its designed position on the lifting section and precisely installed and fixed, ultimately completing the high-altitude assembly of the entire curved steel truss.

[0037] This method of first using the rear-mounted section to balance the center of gravity for lifting, and then resetting the rear-mounted section at high altitude, cleverly solves the hoisting problem caused by the shift in the center of gravity of the curved steel truss, ensuring the safety and efficiency of construction.

[0038] In another possible embodiment of the present invention, the selection of post-installed members based on the center of gravity offset and eccentricity of the arc-shaped steel truss includes: S410. Obtain the overall mass distribution of the arc-shaped steel truss and determine the original center of gravity position and eccentricity. S420. Identify multiple members in the arc-shaped steel truss that are opposite to the direction in which the center of gravity is biased to one side, and calculate the torque of the multiple members; S430. Select the rod with the largest torque as the post-installed rod.

[0039] In this embodiment, firstly, a digital model of the arc-shaped steel truss is constructed using 3D modeling software or BIM technology. Then, parameters such as the material density and geometric dimensions of each component are input to accurately calculate the overall mass distribution of the entire steel truss.

[0040] Based on this mass distribution, the original center of gravity coordinates of the curved steel truss before segmentation are determined using the center of gravity calculation formula or professional structural analysis software. Then, the original center of gravity position is compared with the preset centroid position of the lifting point, and the horizontal distance between the two is calculated. This distance is the eccentricity e, which directly reflects the degree to which the center of gravity of the steel truss deviates from the centroid of the lifting point. Next, according to the determined original center of gravity bias, for example, if the center of gravity is biased towards the inner side of the curved steel truss, all members located in the steel truss structure in the opposite direction (i.e., the outer side) to the biased side (inner side) are identified. For these identified members, their moments about the centroid of the lifting point are calculated one by one.

[0041] The torque is calculated strictly according to the formula Mi=Gi*Li*sinθi, where Gi is the weight of each member, which can be calculated from the member's volume and material density; Li is the horizontal distance from the member's center of gravity to the centroid of the lifting point, which is obtained through model coordinate measurement; θi is the angle between the line connecting the member's center of gravity and the centroid of the lifting point and the horizontal plane, which can also be determined using the geometric relationships in the model. After calculating the torque of all candidate members, numerical comparisons are performed, and the member with the largest torque value is selected as the post-installed member.

[0042] The reason for choosing the rod with the largest torque as the core component of the rear section is that it can contribute the largest balancing torque with the smallest weight when used as a temporary counterweight, thereby more effectively counteracting the eccentric torque of the lifting section and making the center of gravity adjustment effect of the lifting section more significant.

[0043] Furthermore, selecting the member with the largest torque as the post-installed member includes: S431. When there are members with equal torque contributions, the member on the outer side of the arc that is far from the lifting point shall be selected, or the member with fewer nodes and easier to assemble and disassemble shall be selected.

[0044] In this embodiment, if calculations reveal multiple members with the same moment contribution value that can be considered as candidates for subsequent installation members, further screening is required to determine the optimal solution. In this case, members located on the outer side of the arc of the curved steel truss and far from the centroid of the lifting point are given priority. This is because, due to their positional characteristics, such members, when installed as temporary counterweights in the lifting section, can form a longer lever arm, resulting in a better balance effect under the same weight and facilitating precise adjustment of the center of gravity. If members on the outer side of the arc far from the lifting point are still not unique or are subject to other limitations, members with fewer nodes, simpler structures, and easier assembly / disassembly operations are considered. Selecting members with fewer nodes reduces the workload of temporary connections, lowers the operational difficulty and time cost during installation and subsequent disassembly, and also reduces temporary modifications to the original structure of the lifting section, improving construction efficiency and reducing potential impacts on structural stability.

[0045] This principle allows for further optimization of the selection of post-installation sections while ensuring torque contribution, thus guaranteeing ease and economy of construction. Furthermore, when selecting post-installation members, they can be single members or combinations of members in different positions. When multiple members are combined as a post-installation section, it is essential to ensure that the torque directions of each member are consistent, collectively forming a total torque opposite to the eccentricity of the lifting section, thereby effectively adjusting the overall center of gravity. For example, if the center of gravity of the lifting section is biased to the left, multiple members with positive torque contributions on the right side can be combined. By superimposing the torques of each member, the combined post-installation section generates sufficient reverse torque to balance the left-side eccentricity. During the combination selection process, the weight, positional distribution, and connection method of each member must also be comprehensively considered to avoid increased assembly complexity of the lifting section or decreased structural stability after temporary counterweight installation due to an excessive number of combined members or an unreasonable layout.

[0046] In one possible embodiment of the present invention, in the above-described operation step of installing the rear-mounted section as a temporary counterweight on the lifting section, so that the center of gravity of the lifting section is approximately coincident with the centroid of the lifting point, the total torque contribution ∑M of the rear-mounted section should be guaranteed. i The eccentric torque M of the lifting section e Within the predetermined threshold deviation and in the opposite direction; wherein, the predetermined threshold deviation is set according to the engineering construction accuracy requirements, and is usually controlled within 5% to ensure the overall stability of the lifting section during the hoisting process.

[0047] Specifically, this is achieved by calculating the eccentric moment Me (Me=G) of the lifting section before the installation of the post-installation section. 总 ×e, G 总 Let ξ be the total weight of the truss, and e be the eccentricity between the original center of gravity and the centroid of the lifting point. Then, based on the total moment contribution of the post-installed section ∑M... i (∑M) i =∑(G 后i ×L 后i ×sinθ 后i ), G 后i L represents the weight of each member in the post-installation section. 后i θ is the horizontal distance from the center of gravity of each member in the post-installation section to the centroid of the lifting point. 后i (The angle between the line connecting the center of gravity of each member of the post-installed section to the centroid of the lifting point and the horizontal plane) is used to adjust the installation position or combination method of the post-installed section so that ∑M i With M e The difference in absolute value and M e The ratio does not exceed a predetermined threshold, and ∑M i Direction and M e Conversely, this allows for precise pre-matching of the lifting segment's center of gravity. For example, if the original eccentric torque M of the lifting segment... eIf the torque is 100 kN·m in the clockwise direction, the rear section needs to provide a total torque contribution of 95 kN·m to 105 kN·m in the counterclockwise direction to meet the predetermined threshold deviation requirement. In actual operation, the installation position of the rear section can be finely adjusted by setting a temporary adjustment device (such as a movable counterweight or fine-tuning connection node) on the lifting section until the deviation between the center of gravity and the centroid of the lifting point meets the design requirements, thus laying a safe foundation for subsequent lifting operations.

[0048] Furthermore, to facilitate the adjustment of the total moment contribution of the rear-mounted section and the eccentric moment of the lifting section, and to ensure structural stability and strength during the hoisting process, in this embodiment, the installation of the rear-mounted section as a temporary counterweight on the lifting section includes: S510. Several temporary reinforcing members are installed on the lifting section, and the several temporary reinforcing members are fixedly connected to the middle truss. S520. Fix the post-installed section to the nodes of the temporary reinforcing members.

[0049] In this embodiment, to ensure the connection reliability and structural stability of the post-installed section when it is installed on the lifting section as a temporary counterweight, several temporary reinforcing members are first added inside the middle truss of the lifting section. These temporary reinforcing members are usually made of steel of the same type or higher strength as the original structural members. They are fixedly connected to the main nodes or chords of the middle truss by welding or bolting according to the preset force path, forming a locally reinforced temporary load-bearing system.

[0050] For example, such as Figure 4 As shown, diagonal supports or horizontal tie rods can be added between the upper and lower chords of the middle truss 12 to form temporary reinforcing members 50, thereby enhancing the overall rigidity of the lifting section under the action of temporary counterweight and preventing local deformation or instability of the lifting section due to the additional weight of the subsequent section. Subsequently, each member of the subsequent section 40 is precisely fixed at the preset node positions of these temporary reinforcing members by means of high-strength bolts or temporary welding. The node design of the temporary reinforcing members 50 needs to be verified by structural stress calculation to ensure that it can withstand the weight of the subsequent section and the dynamic load during the hoisting process. At the same time, the selection of node positions should facilitate the installation and subsequent disassembly of the subsequent section to avoid damage to the original structure of the lifting section.

[0051] By setting up temporary reinforcing members 50, a stable installation foundation is provided for the post-installation section, and the load transferred from the post-installation section to the lifting section is effectively distributed, ensuring the structural safety of the lifting section during ground assembly and hoisting.

[0052] Specifically, the temporary reinforcing member is Hw200×200 steel, and the post-installed section is fixed at the four-quarter node of the member. The position of this node is determined by stress calculation, which can effectively distribute the weight of the post-installed section, avoid local stress concentration in the lifting section, and ensure that the post-installed section will not loosen or shift during the hoisting process.

[0053] Based on the above embodiments, the actual operation flow of the pre-matching segmentation method for the center of gravity of the arc-shaped steel truss according to the present invention is as follows: First, on the permanent structure on one side of the building, two cantilevered supports are set up in a mirror image at a predetermined angle according to step S110, and the number, position and load-bearing parameters of the lifting points on the two supports are completely consistent, so as to provide symmetrical and stable support for subsequent hoisting.

[0054] Next, a digital model of the curved steel truss is constructed using 3D modeling software or BIM technology. Parameters for each component are input, and step S410 is executed to obtain the overall mass distribution, determining the original center of gravity position and eccentricity e. Subsequently, based on the original center of gravity offset, multiple members with opposite directions are identified. Step S420 calculates the moment of each member about the centroid of the lifting point, and step S430 selects the member with the largest moment as the subsequent assembly member. If members with equal moments exist, priority is given to members on the outer side of the arc that are far from the lifting point or have fewer nodes and are easy to assemble and disassemble. If necessary, multiple members with the same moment direction can be combined to form a subsequent assembly section.

[0055] Next, the lifting section (composed of inner steel beams, remaining central truss and remaining external cantilever structure) is assembled on the ground. Then, in step S510, temporary Hw200×200 steel reinforcement members are installed in the central truss of the lifting section. These members are fixed by welding or bolts to form a local reinforcement system. Finally, in step S520, the post-installed section is fixed at the quarter-node of the temporary reinforcement members (determined by stress calculation).

[0056] During installation, ensure the total torque contribution ∑M of the post-installed section. i With the eccentric torque Me of the lifting section (Me=G) 总 (e) If the directions are opposite and the deviation is within 5%, the position of the post-installed section can be finely adjusted using a temporary adjustment device to meet the accuracy requirements. After completion, follow step S610 to control the synchronous movement of the lifting points of the two cantilever supports, smoothly lift the lifting section to the design elevation, and connect it with the pre-installed section using high-strength bolts or welding; finally, execute step S620 to disassemble the post-installed section and install it back to the design position of the lifting section, completing the high-altitude assembly of the entire curved steel truss.

[0057] Through the above operational steps, this invention establishes a truss moment distribution function, using the centroids of two identical lifting points as the target equilibrium points, and divides the truss into pre-assembly, lifting, and post-assembly sections, minimizing the deviation between the center of gravity of the lifting section and the centroid of the lifting points. This invention solves the problem of eccentric lifting of curved trusses by optimizing construction segmentation without altering the symmetry of the support and lifting points, avoiding the need for asymmetrical lifting points or excessive counterweights, and offering advantages such as simple construction and high safety and reliability.

[0058] In summary, this invention provides a method for pre-matching the center of gravity of an arc-shaped steel truss. This method includes: setting up cantilever supports, each including several lifting points; dividing the arc-shaped steel truss into inner steel beams, a central truss, and an outer cantilever structure based on structural characteristics; defining the top sides and connecting structures of the central truss as pre-assembled sections, which are pre-installed on a single side of the building's permanent structure; selecting post-installed members based on the center of gravity offset and eccentricity of the arc-shaped steel truss, defining the post-installed members and a portion of the upper chord of the outer cantilever structure as post-installed sections; defining the inner steel beams, the remaining central truss, and the remaining outer cantilever structure as lifting sections; assembling the lifting sections on the ground, and installing the post-installed sections as temporary counterweights on the lifting sections, so that the center of gravity of the lifting sections nearly coincides with the centroid of the lifting points. This invention divides the arc-shaped steel truss into a pre-assembly section, a lifting section, and a post-assembly section by matching the center of gravity. The post-assembly section is installed as a temporary counterweight on the lifting section after it is assembled on the ground. On the one hand, this minimizes the deviation between the center of gravity of the lifting section and the centroid of the lifting point. On the other hand, it simplifies the lifting process. Without changing the symmetry of the support and the lifting point, the eccentric lifting problem of the arc-shaped truss is solved by optimizing the construction segmentation. This avoids setting asymmetrical lifting points or adding a large amount of counterweight. It has the advantages of reducing the impact of external factors on the lifting process, simple construction, and safety and reliability.

[0059] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for pre-matching the center of gravity of a curved steel truss, characterized in that, The method for pre-matching the center of gravity of curved steel trusses includes: A cantilevered support is provided, the cantilevered support including several suspension points; Based on structural characteristics, the arc-shaped steel truss is divided into inner steel beams, middle truss, and outer cantilever structure; The top sides and connecting structures of the central truss are defined as pre-installed sections, which are pre-installed on the permanent structure on one side of the building. Based on the center of gravity offset and eccentricity of the arc-shaped steel truss, the post-installed members are selected, and the post-installed members and part of the upper chord in the external cantilever structure are defined as post-installed sections; the inner steel beam, the remaining middle truss, and the remaining external cantilever structure are defined as lifting sections; The lifting section is assembled on the ground, and the post-installed section is installed on the lifting section as a temporary counterweight, so that the center of gravity of the lifting section is nearly coincident with the centroid of the lifting point.

2. The method for pre-matching the center of gravity of an arc-shaped steel truss according to claim 1, characterized in that, A cantilevered support is provided, the cantilevered support including several suspension points, including: Two cantilever supports are installed on the permanent structure on one side of the building. The two cantilever supports are mirror images of each other at a predetermined angle, and the suspension points of the two cantilever supports are the same.

3. The method for pre-matching the center of gravity of an arc-shaped steel truss according to claim 2, characterized in that, The process of assembling the lifting section on the ground and installing the post-installed section as a temporary counterweight on the lifting section, so that the center of gravity of the lifting section is nearly coincident with the centroid of the lifting point, further includes: The lifting section is raised to the design elevation through the lifting points of the two cantilever brackets, and the lifting section and the pre-assembled section are connected. Disassemble the rear section and install it at the designed position of the lifting section.

4. The method for pre-matching the center of gravity of an arc-shaped steel truss according to claim 1, characterized in that, The selection of post-installed members based on the center of gravity offset and eccentricity of the arc-shaped steel truss includes: Obtain the overall mass distribution of the curved steel truss and determine the original center of gravity position and eccentricity; Identify multiple members in the arc-shaped steel truss that are opposite to the direction in which the center of gravity is biased to one side, and calculate the moments of the multiple members; The member with the largest torque is selected as the post-installed member.

5. The method for pre-matching the center of gravity of an arc-shaped steel truss according to claim 4, characterized in that, The step of selecting the member with the largest torque as the post-installed member includes: When there are members with equal torque contributions, the member on the outer side of the arc that is far from the lifting point is selected, or the member with fewer nodes and easier assembly and disassembly is selected.

6. The method for pre-matching the center of gravity of an arc-shaped steel truss according to claim 4, characterized in that, The post-installed member can be a single member or a combination of members in different positions.

7. The method for pre-matching the center of gravity of an arc-shaped steel truss according to claim 4, characterized in that, The formula for calculating the torque of the rod is: M i =G i *L i *sinθ i ; Among them, M i G is the torque of the rod. i For the weight of the rod, L i θ is the horizontal distance from the center of gravity of the member to the centroid of the lifting point. i It is the angle between the line connecting the center of gravity of the member and the centroid of the suspension point and the horizontal plane.

8. The method for pre-matching the center of gravity of an arc-shaped steel truss according to claim 1, characterized in that, The total torque contribution of the rear section ∑M i The eccentric torque M of the lifting section e Within the predetermined threshold deviation and in the opposite direction; The eccentric torque M of the lifting section e The calculation formula is: M e =G 总 ×e; Among them, G 总 denoted as the total weight of the truss, and e as the eccentricity between the original center of gravity and the centroid of the suspension point.

9. The method for pre-matching the center of gravity of an arc-shaped steel truss according to claim 1, characterized in that, Installing the rear-loading section as a temporary counterweight on the lifting section includes: Several temporary reinforcing members are installed on the lifting section, and the temporary reinforcing members are fixedly connected to the middle truss. The post-installed section is fixed to the nodes of several of the temporary reinforcing members.

10. The method for pre-matching the center of gravity of an arc-shaped steel truss according to claim 9, characterized in that, The temporary reinforcing member is an Hw200×200 steel section, and the post-installed section is fixed at the four-quarter node of the member.

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