A hoisting method and device based on beam string dimension parameters

Abstract

The present application belongs to the field of building structure construction, and relates to a hoisting method and device based on size parameters of a beam string, aiming to solve the problems of high risk of out-of-plane instability, unreasonable stress of hoisting points and insufficient precision of synchronous control of double machines in the process of hoisting a large-span variable-height beam string. The present application comprises: calculating the position of the hoisting point; fixing two hangers below each hoisting point and connecting them through a horizontal connecting rod, with the middle part of the hanger connected to the upper chord of the beam string and the upper end of the hoisting point located above the center of gravity of the cross section; two cranes are respectively connected to the upper end of the two hangers through a steel wire rope; calculating the load distribution according to the distance between the center of gravity and the hoisting point; obtaining the height deviation value and the actual load value in real time during the synchronous lifting process, and adjusting the lifting speed of the crane when the deviation exceeds the preset threshold; fixing and removing the hangers after hoisting in place. The present application improves the out-of-plane stability during hoisting, realizes the balanced distribution of load and the precise control of double-machine synchronization.

Description

Technical Field

[0001] This invention belongs to the field of building structure construction, and specifically relates to a hoisting method and device based on the dimensional parameters of a tensioned beam. Background Technology

[0002] Tensioned beams are prestressed steel structure systems composed of a rigid compression member on the upper chord, a flexible cable on the lower chord, and struts connecting the two. They are widely used in large-span roof structures such as stadiums and convention centers. To accommodate architectural design and drainage requirements, roof tensioned beams often adopt a variable-height polygonal structure, with the upper chord cross-section changing in a polygonal pattern along the span.

[0003] For this type of long-span, variable-height tensioned beam, the component itself is characterized by a high center of gravity, a large slenderness ratio, and a flat, wide rectangular cross-section. When using a crane for hoisting, if the lifting points are located at or near the ends of the tensioned beam, the component will be under compression and bending stress during hoisting because the line connecting the lifting points is below the component's center of gravity, posing a risk of out-of-plane instability and overturning. Furthermore, due to their large weight and length, long-span tensioned beams typically require two cranes for dual-crane lifting. The selection of the lifting point location directly affects the load distribution between the two cranes and the internal force state of the component during hoisting, while the synchronous control of the lifting of the two cranes is also directly related to the safety of the hoisting process.

[0004] In existing technologies, the hoisting of long-span, variable-height tensioned beams typically involves directly installing lifting lugs at both ends of the component for lifting, and controlling the synchronization of two cranes through manual observation and command. This method has the following drawbacks: The location of the lifting point is usually determined based on experience. Without multi-objective optimization calculations for out-of-plane stability and mid-span bending moment based on dimensional parameters such as the span, cross-sectional dimensions, and slenderness ratio of the tensioned beam, it is difficult to take into account both out-of-plane stability and stress rationality during the lifting process. The lack of specialized tooling for changing the height of the lifting point makes it difficult to effectively raise the lifting point above the center of gravity of the component, thus failing to improve the stability of the lifting operation structurally. The synchronous control of the two cranes relies on the operator's experience and visual judgment. There is a lack of real-time monitoring and closed-loop adjustment methods for the height difference between the two ends of the components and the actual load of the cranes. Once a large height difference or load deviation occurs, it is difficult to detect and correct it in a timely manner. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, namely the high risk of out-of-plane instability, unreasonable stress on the lifting points, and insufficient synchronous control accuracy of the two machines during the dual-machine lifting of large-span variable-height tensioned beams, this invention provides a lifting method and device based on the dimensional parameters of the tensioned beam.

[0006] In a first aspect, this invention proposes a hoisting method based on the dimensional parameters of a tensioned beam, comprising: The span, cross-sectional dimensions, and slenderness ratio of the tensioned beam are obtained. With the goal of maximizing the out-of-plane stability coefficient and minimizing the mid-span bending moment, and with the constraint that the local compressive stress at the suspension point does not exceed the compressive strength of the steel, the spatial positions of the two suspension points are calculated. Two hangers are fixed below each of the above-mentioned suspension points on the upper chord of the tensioned beam. The two hangers below the same suspension point are fixedly connected by a horizontal connecting rod. The middle part of the hanger is connected to the upper chord of the tensioned beam, and the upper suspension point of the hanger is located above the centroid of the tensioned beam section. Two cranes are each connected to a corresponding lifting point via slings. The lifting point of each crane is connected to the upper lifting points of two hangers below the lifting point via two sling wire ropes, so that the lifting point and the two upper lifting points form a triangular force transmission configuration. Obtain the center of gravity position of the tension beam, and calculate the load distribution between the two cranes based on the obtained center of gravity position and the horizontal distance between the two lifting points. Two cranes are controlled to lift synchronously. During the lifting process, the height deviation value at both ends of the tension beam and the actual load value of the two cranes are obtained. When the obtained height deviation value exceeds the preset height deviation threshold, or the difference between the obtained actual load value and the load distribution exceeds the preset load deviation threshold, the lifting speed of at least one crane is adjusted so that the height deviation value and the difference are restored to the corresponding threshold range. After the tension beam is hoisted into place, fix the tension beam and remove the hanger.

[0007] Furthermore, the span, cross-sectional dimensions, and slenderness ratio of the tensioned beam are obtained, and the locations of the two suspension points are calculated, including: Obtain the parameters of the tensioned beam, including the span value, the height value of the upper chord section, the width value of the upper chord section, the wall thickness value of the upper chord, and the slenderness ratio value; A mechanical model of the eccentric compression-bending member is established based on the obtained parameters. The estimated axial force and estimated bending moment under the hoisting state are calculated in the mechanical model, and the eccentricity is calculated based on the estimated axial force and estimated bending moment. Using the out-of-plane stability coefficient as the first optimization objective, the mid-span bending moment as the second optimization objective, and the constraint that the local compressive stress at the lifting point does not exceed the compressive strength of the upper chord steel, the position coordinates of the two lifting points in the direction of the upper chord axis are iteratively calculated to obtain the positions of the two lifting points.

[0008] Furthermore, the center of gravity position of the tension beam is obtained, and based on the obtained center of gravity position and the distance between the two lifting points, the load distribution between the two cranes is calculated, including: The crane connected to one lifting point is designated as the first crane, and the crane connected to the other lifting point is designated as the second crane. The lifting point connected to the first crane is designated as the first lifting point, and the lifting point connected to the second crane is designated as the second lifting point. Using the obtained center of gravity position as the torque center, measure the first horizontal distance from the center of gravity position to the first lifting point, and the second horizontal distance from the center of gravity position to the second lifting point; Obtain the total lifting weight of the tensioned beam and the weight of the lifting slings; Establish a moment balance equation, such that the product of the vertical component of the load borne by the first crane and the first horizontal distance is equal to the product of the vertical component of the load borne by the second crane and the second horizontal distance, and the sum of the vertical components of the load borne by the first crane and the second crane is equal to the sum of the total lifting weight and the weight of the slings. Solve the torque balance equation to obtain the load distribution of the first crane and the second crane respectively.

[0009] Furthermore, controlling the synchronous lifting of the two cranes includes: The hoisting command is sent to both cranes simultaneously through a unified command signal system. During each hoisting phase, the hoisting speed of the two cranes is kept consistent, and the difference in hoisting speed does not exceed the preset speed difference threshold.

[0010] Furthermore, adjust the lifting speed of at least one crane, including: When the height deviation value exceeds the height deviation threshold, the crane on the higher side is controlled to reduce its lifting speed or suspend lifting, and / or the crane on the lower side is controlled to increase its lifting speed. When the difference exceeds the load deviation threshold, the crane on the side with the larger actual load value is controlled to reduce its lifting speed or suspend lifting. Once the height deviation value returns to the height deviation threshold range and the difference returns to the load deviation threshold range, the two cranes resume synchronous lifting.

[0011] Furthermore, the method is executed after the tensioned beam is assembled and initially tensioned. The tensioned beam is a variable-height polygonal tensioned beam with a rectangular cross-section for the upper chord. Prestressed cables are installed below the tensioned beam. The two cranes are two truck cranes of the same model and lifting performance parameters, respectively positioned on both sides of the span direction of the tensioned beam for dual-crane lifting.

[0012] Furthermore, the method also includes: Before lifting the tension beam, a trial lift is performed on the tension beam. The trial lift height does not exceed the preset trial lift height. During the trial lift, the connection status of the suspension frame, the braking performance of the two cranes, and the synchronization response status are checked.

[0013] Furthermore, the upper lifting point of the sling is connected to the lower end of the sling via a pin-type connection, and the upper end of the sling is connected to the crane hook.

[0014] In a second aspect, the present invention provides a tensioned beam hoisting device for implementing the method of the first aspect, comprising: Four hangers are arranged in pairs below two hanging points. Each hanger consists of two parallel and spaced vertical bars, the upper ends of which are fixedly connected by an upper horizontal bar, which is provided with an upper lifting point for connecting to the lower end of the sling wire rope; Each of the vertical rods has a pin hole at its middle end, through which a pin passes to connect the vertical rod to a lug plate pre-fixed to the upper chord of the tension beam. A reinforcing plate is fixedly installed on each vertical rod. The reinforcing plate is fixed to the surface of the vertical rod. The pin hole passes through the reinforcing plate. The surface area of ​​the reinforcing plate is larger than the hole area of ​​the pin hole. The upper crossbars of two hangers connected to the same crane are fixedly connected by a horizontal connecting rod; Each crane is equipped with two sling wire ropes. The upper ends of the two sling wire ropes meet at one point to form the lifting point, and the lower ends of the sling wire ropes are respectively connected to the upper lifting point of the corresponding crane frame.

[0015] Furthermore, it also includes: A height deviation sensor is installed at both ends of the tensioned beam to obtain the height deviation value at both ends of the tensioned beam during the lifting process. Load sensing devices are installed on the hooks or slings of two cranes to obtain the actual load values ​​of the two cranes during the lifting process. The control device is communicatively connected to the height deviation sensing device and the load sensing device, and electrically connected to the hoisting control system of the crane. It is used to receive the height deviation value and the actual load value, and when it is determined that the height deviation value exceeds a preset height deviation threshold or the difference between the actual load value and the load distribution exceeds a preset load deviation threshold, it sends a hoisting speed adjustment command to the hoisting control system of the corresponding crane.

[0016] The beneficial effects of this invention are: This invention obtains the span, cross-sectional dimensions, and slenderness ratio of a tensioned beam, aims to maximize the out-of-plane stability coefficient and minimize the mid-span bending moment, and uses the constraint that the local compressive stress at the lifting point does not exceed the compressive strength of the steel to calculate the spatial position of the two lifting points. This makes the determination of the lifting point position no longer rely on empirical judgment, but on multi-objective optimization calculation based on the dimensional parameters of the tensioned beam itself. It takes into account both out-of-plane stability and stress rationality during the lifting process from the source, reduces the risk of out-of-plane instability, and improves the mid-span bending moment distribution.

[0017] This invention improves the out-of-plane stability of the tensioned beam during hoisting by fixing two hangers below each hoisting point on the upper chord of the tensioned beam, with the two hangers at the same hoisting point fixedly connected by a horizontal connecting rod. The middle part of the hanger is connected to the upper chord of the tensioned beam, and the upper hoisting point is located above the center of gravity of the tensioned beam section. This transfers the point of application of the lifting force from below the center of gravity of the component to above the center of gravity, thus improving the out-of-plane stability of the tensioned beam during hoisting and effectively suppressing the tendency to overturn.

[0018] This invention connects the lifting point of each crane to the upper lifting points of two hangers below the lifting point via two sling wire ropes, forming a triangular force transmission configuration between the lifting point and the two upper lifting points. This achieves balanced transmission of the lifting load to the hangers and improves the stability and reliability of the force transmission path during the lifting process.

[0019] This invention obtains the center of gravity position of the tension beam and calculates the load distribution of the two cranes based on the horizontal distance between the center of gravity position and the two lifting points. It establishes a moment balance equation with the center of gravity as the moment center for solution, so that the load distribution calculation has a clear mechanical basis and provides an accurate design reference value for the load monitoring of subsequent dual-crane lifting.

[0020] This invention obtains the height deviation values ​​at both ends of the tension beam and the actual load values ​​of the two cranes in real time during the synchronous lifting process, and adjusts the lifting speed of at least one crane when the height deviation value exceeds a preset threshold or the difference between the actual load value and the load distribution exceeds a preset threshold. This forms a closed-loop control of the synchronous lifting state and load distribution of the two cranes, overcomes the shortcomings of the traditional manual observation and command method in terms of synchronous control accuracy and response timeliness, and improves the safety and controllability of the lifting process.

[0021] This invention provides a pin hole at the middle end of the vertical rod of the hanger for the pin to pass through and connect to the upper chord hanger lug plate. A reinforcing plate with a surface area larger than the pin hole area is fixed on the surface of the vertical rod. This enhances the local bearing capacity at the pin connection node, reduces the risk of local damage caused by stress concentration at the hole edge, and improves the reliability of the connection between the hanger and the tensioned beam.

[0022] This invention connects two hangers into a spatial integral structure by fixing a horizontal connecting rod between the upper crossbars of the two hangers connected to the same crane. This enhances the overall stiffness and lateral stability of the hanger system in the direction of the tension beam axis and constrains the relative displacement and torsion of the hangers during use.

[0023] This invention, by configuring a height deviation sensor, a load sensor, and a control device, monitors and automatically identifies the height difference between the two ends of the tensioned beam and the actual load of the crane in real time. When the limit is exceeded, it automatically sends an adjustment command to the hoisting control system of the corresponding crane, thereby realizing the automation of synchronous control of dual-machine lifting and improving the accuracy and timeliness of synchronous adjustment. Attached Figure Description

[0024] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a flowchart of a hoisting method based on the dimensional parameters of a tensioned beam according to the present invention; Figure 2 This is a schematic diagram of the overall structure of a tensioned beam hoisting device according to the present invention; Figure 3 yes Figure 2 Enlarged view of a section of the central hanger; Figure 4 This is a schematic diagram of a tensioned beam hoisting device according to the present invention during the hoisting process. Detailed Implementation

[0025] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] The first embodiment of the present invention proposes a hoisting method based on the dimensional parameters of a tensioned beam, comprising: Step S10: Obtain the span, cross-sectional dimensions, and slenderness ratio of the tensioned beam. With the goal of maximizing the out-of-plane stability coefficient and minimizing the mid-span bending moment, and with the constraint that the local compressive stress at the suspension point does not exceed the compressive strength of the steel, calculate the spatial position of the two suspension points. Step S20: Fix two hangers below each of the above-mentioned suspension points on the upper chord of the tensioned beam. The two hangers below the same suspension point are fixedly connected by a horizontal connecting rod. The middle part of the hanger is connected to the upper chord of the tensioned beam, and the upper suspension point of the hanger is located above the centroid of the tensioned beam section. Step S30: Connect each of the two cranes to a corresponding lifting point via slings. The lifting point of each crane is connected to the upper lifting points of the two hangers below the lifting point via two sling wire ropes, so that the lifting point and the two upper lifting points form a triangular force transmission configuration. Step S40: Obtain the center of gravity position of the tension beam, and calculate the load distribution of the two cranes based on the obtained center of gravity position and the horizontal distance between the two lifting points. Step S50: Control the two cranes to lift synchronously. During the lifting process, obtain the height deviation value at both ends of the tension beam and the actual load value of the two cranes. When the obtained height deviation value exceeds the preset height deviation threshold, or the difference between the obtained actual load value and the load distribution exceeds the preset load deviation threshold, adjust the lifting speed of at least one crane to restore the height deviation value and the difference to the corresponding threshold range. Step S60: After the tension beam is hoisted into place, fix the tension beam and remove the hanger.

[0028] To more clearly explain the hoisting method based on the dimensional parameters of a tensioned beam according to the present invention, the following is in conjunction with... Figure 1 The steps in the embodiments of the present invention are described in detail below: Step S10: Obtain the span, cross-sectional dimensions, and slenderness ratio of the tensioned beam. With the goal of maximizing the out-of-plane stability coefficient and minimizing the mid-span bending moment, and with the constraint that the local compressive stress at the suspension point does not exceed the compressive strength of the steel, calculate the spatial position of the two suspension points. In this embodiment, the span, cross-sectional dimensions, and slenderness ratio of the tensioned beam are obtained, and the positions of the two suspension points are calculated, including: Step S11: Obtain the parameters of the tensioned beam, including the span value, the height value of the upper chord section, the width value of the upper chord section, the wall thickness value of the upper chord, and the slenderness ratio value. Step S12: Establish a mechanical model of the eccentric compression-bending member based on the obtained parameters, calculate the estimated axial force and estimated bending moment under the hoisting state in the mechanical model, and calculate the eccentricity based on the estimated axial force and estimated bending moment. Step S13: Using the out-of-plane stability coefficient as the first optimization objective, the mid-span bending moment value as the second optimization objective, and the constraint that the local compressive stress at the suspension point does not exceed the compressive strength of the upper chord steel, the position coordinates of the two suspension points in the direction of the upper chord axis are iteratively calculated to obtain the positions of the two suspension points.

[0029] In this invention, to scientifically and accurately determine the optimal lifting point position of a large-span, variable-height tensioned beam under dual-machine lifting conditions, it is first necessary to comprehensively obtain the key structural parameters of the tensioned beam. These parameters are directly provided by the structural design drawings and construction plan of the tensioned beam.

[0030] In this embodiment, the span value L is specifically obtained as follows: 50.4m is preferred for the roof structure of a badminton hall, and 42m is preferred for the roof structure of a basketball / volleyball hall. The cross-sectional geometric dimensions of the upper chord include the cross-sectional height h, the cross-sectional width b, and the flange and web thicknesses of the upper chord. In this embodiment, the typical cross-section of the upper chord used in the badminton hall is preferably 800×350×25×28mm, i.e., the cross-sectional height h is 800mm, the cross-sectional width b is 350mm, the flange thickness is 28mm, and the web thickness is 25mm. In this embodiment, the slenderness ratio λy of the entire tensioned beam bending member is calculated based on the cross-sectional parameters and the geometric shape of the member, or the slenderness ratio λy is directly extracted through overall model analysis. This value reflects the flexibility characteristics of the member and is one of the core indicators for out-of-plane stability assessment. The accurate acquisition of these parameters is the basic prerequisite for establishing a precise mechanical model and performing multi-objective optimization calculations.

[0031] After obtaining the above parameters, this invention does not adopt the traditional method of determining the lifting points based on experience. Instead, it constructs an integrated mechanical model of the eccentrically compressed-bending member that can accurately reflect the actual stress state during the lifting process. In this embodiment, the model is preferably built based on the Midas Gen finite element numerical analysis platform. The entire tensioned beam is discretized into spatial beam elements, and its variable-height polygonal structural morphology, the box-section characteristics of the upper chord, and the stress of the steel material are accurately simulated. The strain constitutive relation is used, and the steel for the upper chord of the badminton hall is preferably Q420B high-strength steel; the boundary conditions are simulated as a lifting state with simple support at both ends. In the constructed mechanical model, the applied load is the structural self-weight considering the construction dynamic amplification effect. In this embodiment, according to relevant specifications, the partial factor for the load combination is preferably 1.3, and the dynamic factor is preferably 1.4. The standard value of the dead load is multiplied by this partial factor and the dynamic factor and combined to form the load design value for strength and stability verification. By running the model for analysis and solution, the estimated axial force N and estimated bending moment M of the tensioned beam under the lifting state can be calculated at a given set of initial lifting point positions. The estimated axial force and estimated bending moment are the most direct mechanical indicators for evaluating the lifting safety. In this embodiment, taking the tensioned beam of the badminton hall with a span of 50.4m as an example, the preliminary analysis of the model shows that the axial force N during the lifting process can reach 380.7kN, and the bending moment M can reach 859.8kN·m. Based on these two internal force values, the eccentricity e can be further calculated, which is equal to the bending moment M divided by the axial force N. In this example, the eccentricity is as high as 2.26m. Such a significant eccentricity intuitively reflects that if the lifting points are not set properly, the component will face an extremely high risk of out-of-plane instability under strong combined compression and bending stress.

[0032] After obtaining the aforementioned mechanical parameters reflecting the eccentric bending stress characteristics, this invention initiates a multi-objective, constrained iterative optimization calculation program to accurately locate the installation position coordinates of the four height-increasing hangers along the axis of the upper chord of the tensioned beam. This optimization process establishes a hierarchical objective function system: the primary optimization objective, the first optimization objective, is to maximize the out-of-plane stability coefficient. Out-of-plane stability is the fundamental guarantee that the tensioned beam, with its high center of gravity and large slenderness ratio, will not experience out-of-plane bending or torsional instability during hoisting. The secondary optimization objective, the second optimization objective, is to minimize the mid-span bending moment. Reducing the mid-span bending moment allows for a more uniform and reasonable stress distribution within the component, reducing redundant requirements on structural strength.

[0033] Meanwhile, this optimization calculation must be performed under a rigid constraint: the local compressive stress of the upper chord at the lifting point must strictly not exceed the design compressive strength of the steel. This is because the lifting point will bear a huge concentrated lifting load during hoisting, and local buckling or crushing failure must be prevented. In this embodiment, the optimization algorithm continuously adjusts the relative position coordinates of the four heightening hangers on the axis of the upper chord during the iteration process. These coordinates are typically represented as distances from the end of the component. Each newly generated set of position coordinates is input into the established mechanical model for iterative solution to obtain the corresponding out-of-plane stability coefficient, mid-span bending moment, and local compressive stress at the lifting point. If the out-of-plane stability coefficient under the new set of coordinates is higher than the previous set, and the mid-span bending moment is lower, while simultaneously satisfying the constraint that the local compressive stress at the lifting point does not exceed the compressive strength of the steel, then this set of coordinates is considered a better solution and is retained. Through dozens or even hundreds of automatic iterations, the calculation eventually converges to a set of installation position coordinates that achieve the optimal balance of the aforementioned multi-objective functions. This set of coordinates represents the theoretically optimal installation positions of the four height-adjusting gantry cranes. The two lifting points determined based on these four installation positions are the theoretically optimal lifting point positions, with each lifting point corresponding to one crane. This calculation method transforms abstract engineering experience problems into concrete and reproducible mathematical optimization problems, fundamentally ensuring the rigor, reliability, and safety of the large-span variable-height tensioned beam hoisting scheme at the mechanical level.

[0034] The optimization problem described above, which aims to maximize the out-of-plane stability coefficient and minimize the mid-span bending moment, is a multi-objective optimization problem. The two objectives conflict in terms of dimensions and trends—the out-of-plane stability coefficient is dimensionless and should be as large as possible, while the mid-span bending moment is a dimensional quantity (kN·m) and should be as small as possible. This invention uses a linear weighted combination method to transform this multi-objective optimization problem into a single-objective optimization problem for solution, constructing a unified objective function as follows: ; in, The position variable of the lifting point is to be determined (expressed as the horizontal distance of the lifting point from the end of the tensioned beam); This is the out-of-plane stability coefficient, with a value ranging from 0 to 1; M0 is the mid-span bending moment value, in kN·m; M0 is the normalized baseline value of the mid-span bending moment, which is taken as the mid-span bending moment value corresponding to the extreme positions of the lifting points at both ends. and These are the weighting coefficients for the two optimization objectives. In this embodiment, out-of-plane stability, the primary safety indicator, is prioritized, and the weighting coefficients are set to... =0.7, =0.3. This value gives greater weight to changes in the out-of-plane stability coefficient on the objective function value, ensuring sufficient redundancy in the optimization results in terms of safety.

[0035] After determining the objective function and constraints, an iterative strategy combining global search and local optimization is used to determine the optimal lifting point location. The specific steps are as follows: The first step is to define the search space: the search domain is the axis of the upper chord of the tensioned beam, and the positions of the two suspension points are defined by their distance from their nearest ends. and The search range is set to be between 0.15L and 0.35L from the end (L is the span of the tensioned beam), which covers the mechanically reasonable distribution area of ​​the suspension points.

[0036] The second step is a global coarse search: Within the search space, a mesh of all suspension point combinations is generated with a step size of 0.5m (for a 50.4m span cable-stayed beam in a badminton hall). For each combination, the Midas Gen finite element model is used to perform mechanical solutions, extracting the out-of-plane stability coefficient. Mid-span bending moment and local compressive stress at the lifting point Local compressive stress at the lifting point. Exceeding the design value of the compressive strength of the upper chord steel Combinations that do not meet the constraints are directly eliminated and not considered as candidate solutions. For the remaining combinations that satisfy the constraints, the objective function formula described above is used for calculation. value.

[0037] The third step is local fine search: Select the three sets of positions with the smallest objective function value in the global coarse search as the initial points of the fine search. Perform a local fine-grained search in the neighborhood of each initial point with a step size of 0.1m, calculate the objective function value of each set of positions again, and select the set that minimizes the objective function value as the optimal solution.

[0038] Step 4, Output the results: Output the optimal position coordinates obtained in step 3. The two final lifting point locations are used to simultaneously output the out-of-plane stability coefficient, mid-span bending moment, and local compressive stress value of each location for safety verification in subsequent steps.

[0039] In this embodiment, taking the ZXL-4 tensioned beam with a span of 50.4m in a badminton hall as an example, after the above iterative calculation, the optimal suspension point position converges to 18.15m and 18.95m from the center of gravity on both sides. The corresponding out-of-plane stability stress ratio is 0.830, which meets the specification requirement of not exceeding 1.0. The mid-span bending moment is reduced by about 35% compared with the two-end lifting scheme. The local compressive stress at the suspension point is 0.72 times the compressive strength of the steel, which meets the constraint conditions.

[0040] Step S20: Fix two hangers below each of the above-mentioned suspension points on the upper chord of the tensioned beam. The two hangers below the same suspension point are fixedly connected by a horizontal connecting rod. The middle part of the hanger is connected to the upper chord of the tensioned beam, and the upper suspension point of the hanger is located above the centroid of the tensioned beam section. After obtaining two optimal lifting point positions through the aforementioned multi-objective optimization calculations, this embodiment proceeds to the installation of the hangers and connection with the crane. On the upper chord of the tensioned beam, which has been assembled on the ground and initially tensioned, positioning lines corresponding to the calculated lifting point positions are accurately marked. In this embodiment, two hangers are fixed below each lifting point, and the two hangers below the same lifting point are fixedly connected by a horizontal connecting rod. The middle of each hanger is securely connected to a lifting lug plate pre-welded and fixed to the side or top surface of the upper chord of the tensioned beam via a pin-type connection structure, thereby reliably fixing the hanger to the upper chord. The structure of the hanger is designed to extend upwards, so that after installation, the uppermost lifting point connection hole is significantly higher in the vertical direction than the centroid of the tensioned beam section. This transfers the point of application of the lifting force from below the component's center of gravity to above it, fundamentally solving the out-of-plane overturning risk caused by the center of gravity being higher than the lifting point connection line during the hoisting of a variable-height tensioned beam.

[0041] Step S30: Connect each of the two cranes to a corresponding lifting point via slings. The lifting point of each crane is connected to the upper lifting points of the two hangers below the lifting point via two sling wire ropes, so that the lifting point and the two upper lifting points form a triangular force transmission configuration. In this embodiment, two cranes are each connected to a corresponding lifting point via slings. The slings are a complete lifting device connecting the crane hook and the suspension frame, including sling wire ropes, shackles, and pins. Specifically, the lifting point connected to each crane is connected to the upper lifting points of the two suspension frames below that lifting point via two sling wire ropes. The lower ends of the sling wire ropes are connected to the upper lifting point holes at the top of the suspension frame via shackles or pins. The upper ends of the two sling wire ropes converge at one point to form a lifting point, which is then suspended from the hook of the corresponding crane. Thus, the lifting point and the two upper lifting points form a triangular force transmission configuration in space.

[0042] In this embodiment, the two cranes used are preferably two truck cranes with the same model, rated lifting capacity and lifting performance curve, which are deployed on both sides of the span direction of the tension beam to form a symmetrical double-crane lifting configuration, so as to ensure the basic balance of the force system during the lifting process.

[0043] Step S40: Obtain the center of gravity position of the tension beam, and calculate the load distribution of the two cranes based on the obtained center of gravity position and the horizontal distance between the two lifting points. In this embodiment, step S40 specifically includes: Step S41: The crane connected to one lifting point is designated as the first crane, and the crane connected to the other lifting point is designated as the second crane. The lifting point connected to the first crane is designated as the first lifting point, and the lifting point connected to the second crane is designated as the second lifting point. Step S42: Using the obtained center of gravity position as the torque center, measure the first horizontal distance from the center of gravity position to the first lifting point, and the second horizontal distance from the center of gravity position to the second lifting point; Step S43: Obtain the total lifting weight of the tensioned beam and the weight of the lifting slings; Step S44: Establish a moment balance equation, such that the product of the vertical component of the load borne by the first crane and the first horizontal distance is equal to the product of the vertical component of the load borne by the second crane and the second horizontal distance, and the sum of the vertical components of the load borne by the first crane and the second crane is equal to the sum of the total lifting weight and the weight of the slings. Step S45: Solve the torque balance equation to obtain the load distribution of the first crane and the second crane respectively.

[0044] In this embodiment, to clarify the correspondence between the objects in the load distribution calculation process, the crane connected to one of the lifting points of the two cranes is designated as the first crane, and the other crane is designated as the second crane; correspondingly, the lifting point connected to the first crane is designated as the first lifting point, and the lifting point connected to the second crane is designated as the second lifting point.

[0045] The center of gravity of the tensioned beam was precisely calculated using the Midas Gen finite element numerical analysis platform during the establishment of the integrated mechanical model of the eccentric compression-bending member. This calculation was based on the variable-height polygonal geometry of the tensioned beam, the wall thickness distribution of the upper chord box section, and the mass distribution of auxiliary components such as struts and cables. Using this center of gravity as the moment center, the horizontal distance from the center of gravity to the first lifting point was measured along the axis of the upper chord of the tensioned beam and recorded as the first horizontal distance d1; the horizontal distance from the center of gravity to the second lifting point was measured and recorded as the second horizontal distance d2. The values ​​of these two horizontal distances directly determine the proportional relationship of the load distribution between the two cranes.

[0046] Obtain the total lifting weight of the tensioned beam and the weight of the slings. In this embodiment, the total lifting weight of the tensioned beam includes the self-weight of all structural components involved in the lifting, such as the upper chord, struts, lower chord prestressed cables, and connecting node plates. Taking a typical tensioned beam with a span of 50.4m for a badminton hall as an example, the weight of the entire tensioned beam, including the prestressed cables, is approximately 35.5t. Taking a typical tensioned beam with a span of 42m for a basketball / volleyball hall as an example, the weight of the entire tensioned beam, including the prestressed cables, is approximately 24t. The weight of the slings includes the self-weight of all lifting equipment, such as wire ropes, shackles, balance beams, and connecting pins. In this embodiment, the weight of the slings is uniformly taken as 1.5t. The sum of the total lifting weight and the weight of the slings constitutes the total lifting load.

[0047] Establish the moment balance equations. Taking the projection point of the center of gravity onto the horizontal plane as the moment center, under the ideal state of stable lifting by two cranes, the product of the vertical component F1 of the load borne by the first crane and the first horizontal distance d1 is equal to the product of the vertical component F2 of the load borne by the second crane and the second horizontal distance d2, i.e., F1×d1=F2×d2. Simultaneously, according to the equilibrium condition of vertical forces, the sum of the vertical components of the loads borne by the first and second cranes is equal to the total lifting load, i.e., F1+F2=G+g, where G is the total lifting weight of the tensioned beam and g is the weight of the slings. Solving these two equations simultaneously constitutes the moment balance equation system.

[0048] Solving the above set of moment balance equations, we obtain the load distribution values ​​for the first and second cranes: F1 = (G + g) × d2 / (d1 + d2), F2 = (G + g) × d1 / (d1 + d2). Taking a tensioned beam in a badminton hall as an example, the total lifting weight G is taken as 35.5t, the weight of the slings g is taken as 1.5t, the total lifting load is 37.0t, the measured first horizontal spacing d1 is 18.15m, and the second horizontal spacing d2 is 18.95m; substituting these values, we get the load of the first crane F1 = 37.0 × 18.95 / (18.15 + 18.95) = 18.9t, and the load of the second crane F2 = 37.0 × 18.15 / (18.15 + 18.95) = 18.1t. The load allocation value is used to verify whether the rated lifting capacity of each crane meets the safety requirements. In this embodiment, the dual-crane lifting is verified by reducing the lifting performance of a single truck crane to 80%, and the allocated lifting weight shall not exceed 75% of the total allowable lifting capacity of the two truck cranes. Only after these two conditions are met can the subsequent lifting steps be carried out.

[0049] Step S50: Control the two cranes to lift synchronously. During the lifting process, obtain the height deviation value at both ends of the tension beam and the actual load value of the two cranes. When the obtained height deviation value exceeds the preset height deviation threshold, or the difference between the obtained actual load value and the load distribution exceeds the preset load deviation threshold, adjust the lifting speed of at least one crane to restore the height deviation value and the difference to the corresponding threshold range. In this embodiment, controlling the synchronous lifting of two cranes includes: The hoisting command is sent to both cranes simultaneously through a unified command signal system. During each hoisting phase, the hoisting speed of the two cranes is kept consistent, and the difference in hoisting speed does not exceed the preset speed difference threshold.

[0050] Adjusting the lifting speed of at least one crane, including: When the height deviation value exceeds the height deviation threshold, the crane on the higher side is controlled to reduce its lifting speed or suspend lifting, and / or the crane on the lower side is controlled to increase its lifting speed. When the difference exceeds the load deviation threshold, the crane on the side with the larger actual load value is controlled to reduce its lifting speed or suspend lifting. Once the height deviation value returns to the height deviation threshold range and the difference returns to the load deviation threshold range, the two cranes resume synchronous lifting.

[0051] In this embodiment, the synchronous lifting control of the dual-crane lifting system is achieved through a unified command signal system and a closed-loop adjustment mechanism. Lifting commands are sent to both cranes simultaneously, maintaining consistent winch speeds at each lifting stage. In this embodiment, a preset speed difference threshold is set to 0.1 m / s, meaning the difference in lifting speed between the two cranes at any given time must not exceed 0.1 m / s. Low-speed, smooth operation is employed throughout the process, prohibiting sudden stops, rapid lifts, or abrupt changes in amplitude to fundamentally suppress height deviations and load transfers caused by speed asynchrony.

[0052] During the lifting process, the height deviation values ​​at both ends of the tensioned beam and the actual load values ​​of the two cranes are acquired in real time. The height deviation values ​​at both ends of the tensioned beam are obtained by observation using a long ruler combined with a level instrument installed at both ends of the tensioned beam, or by automatic acquisition using height deviation sensing devices installed at both ends of the tensioned beam; the actual load values ​​of the two cranes are measured in real time by load sensing devices installed on the crane hooks or slings. The real-time acquired height deviation values ​​are compared with a preset height deviation threshold, and the difference between the real-time acquired actual load values ​​and the load distribution value calculated in step S45 is calculated and compared with the preset load deviation threshold. In this embodiment, the preset height deviation threshold is set to 50mm, that is, the height difference between the two ends of the tensioned beam must not exceed 50mm at any time; the preset load deviation threshold is set to ±10% of the design load distribution value. Taking a tensioned beam in a badminton hall as an example, the design load distribution value of the first crane is 18.9t, then its actual load value is allowed to range from 17.01t to 20.79t, and adjustments are triggered if this range is exceeded.

[0053] When the obtained height deviation value exceeds the preset 50mm height deviation threshold, it indicates that there is a height difference between the two ends of the tensioned beam that exceeds the allowable range. At this time, the lifting speed of at least one crane should be adjusted. The adjustment method is to control the crane on the higher side to reduce its lifting speed or stop lifting, and / or control the crane on the lower side to increase its lifting speed. When the difference between the obtained actual load value and the load distribution value exceeds the preset ±10% load deviation threshold, it indicates that the actual force on the two cranes has deviated from the design distribution value. At this time, the crane on the side with the larger actual load value should reduce its lifting speed or stop lifting. All the above adjustments should be performed using inching, small-amplitude, single-action correction methods. Large-amplitude movements are strictly prohibited to avoid exacerbating component swaying or instability due to over-adjustment.

[0054] During the deviation correction process, changes in height deviation and load difference are continuously monitored. Once the height deviation returns to within 50mm and the difference between the actual load and the load distribution value returns to within ±10%, the synchronous lifting state of the two cranes is immediately restored, and subsequent lifting steps continue. Through the above-mentioned closed-loop control process of unified command, real-time monitoring, threshold judgment, single-action correction, and restoration of synchronization, precise control of the synchronous lifting state and load distribution of the two cranes is achieved, ensuring the safety and stability of the entire lifting process of the large-span variable-height tensioned beam.

[0055] Step S60: After the tension beam is hoisted into place, fix the tension beam and remove the hanger.

[0056] In this embodiment, after the tensioned beam is lifted to the design elevation and stably positioned above the column top support by two cranes, the fixing and scaffold removal steps are performed. The two cranes maintain their current lifting height and lock the winch mechanism, keeping the tensioned beam in a stable suspended state. Construction personnel accurately align the support base plates at both ends of the tensioned beam with the pre-embedded fixed hinge supports at the column top, insert the support connecting bolts, and tighten them symmetrically in steps according to the design torque value, completing the reliable fixing of both ends of the tensioned beam to the main structure.

[0057] After the two ends of the tensioned beam are fixed, at least two to three connecting secondary beams should be installed promptly to ensure the lateral stability of the tensioned beam after the slings are released. The connecting secondary beams are hoisted into place using a tower crane or other auxiliary lifting equipment and connected to the secondary beam connection node plates of the upper chord of the tensioned beam using bolts or welding. Once the connecting secondary beams are installed and the lateral stabilization system of the tensioned beam is formed, the scaffolding can be removed.

[0058] During the removal of the gantry, the two cranes slightly lowered their hooks to loosen the slings from a stressed state. Workers then removed the connecting pins or shackles between the upper lifting point of the gantry and the lower end of the slings, severing the force transmission path between the cranes and the gantry. Subsequently, the connecting pins between the middle vertical member of the gantry and the lifting lug plate of the upper chord of the tensioned beam were removed, and the entire gantry was moved away from the upper chord of the tensioned beam and transported to the ground for centralized storage for reuse in subsequent tensioned beam installations. After removal, the two cranes retracted their hooks and left the site, concluding the installation operation for that tensioned beam.

[0059] Furthermore, the method is executed after the tensioned beam is assembled and initially tensioned. The tensioned beam is a variable-height polygonal tensioned beam with a rectangular cross-section for the upper chord. Prestressed cables are installed below the tensioned beam. The two cranes are two truck cranes of the same model and lifting performance parameters, respectively positioned on both sides of the span direction of the tensioned beam for dual-crane lifting.

[0060] The method further includes: Before lifting the tension beam, a trial lift is performed on the tension beam. The trial lift height does not exceed the preset trial lift height. During the trial lift, the connection status of the suspension frame, the braking performance of the two cranes, and the synchronization response status are checked.

[0061] Before the formal lifting of the tensioned beam, a trial lift is conducted. During the trial lift, the lifting height of the tensioned beam is controlled to not exceed the preset trial lift height. Under trial lift conditions, the connection of the suspension system is checked for security, and the pin connections are inspected for looseness or deformation. The braking performance of both cranes is checked to ensure the braking system can effectively brake and maintain the load. The synchronization response of the two cranes is checked to confirm that the lifting commands issued by the unified command signal system can be executed synchronously by both cranes, and that the winch speeds are consistent. Only after the trial lift passes the inspection can the formal lifting phase begin.

[0062] In this embodiment, the upper lifting point of the sling is connected to the lower end of the sling through a pin-type connection structure, and the upper end of the sling is connected to the crane hook.

[0063] In this embodiment, the hoisting method is performed after the tensioned beam is assembled on the ground and initially tensioned. The tensioned beam is a variable-height, polygonal tensioned beam with a rectangular cross-section for its upper chord. A typical upper chord cross-section for a badminton hall is 800×350×25×28mm, while for a basketball / volleyball hall it is 700×350×20×28mm. Prestressed cables are installed below the tensioned beam; the cable diameter for the badminton hall is φ100, and for the basketball / volleyball hall it is φ80. After assembly, the tensioned beam is in its original vertical assembly state on the jig, with the cables approximately 200mm above the ground. Initial tensioning is applied at 10% of the design tension. In this embodiment, the initial tension of the φ100 cable in the badminton hall is 80kN, and the initial tension of the φ80 cable in the basketball / volleyball hall is 60kN. This initial tension provides the cable with a certain preload, ensuring that the deformation of the tensioned beam is controllable during hoisting, achieving a permanent-temporary connection. Slippage of the end supports of the tensioned beam is permitted during the hoisting stage to release some temperature stress and installation errors.

[0064] In this embodiment, the two cranes used are two truck cranes of identical model and lifting performance parameters. Two 300t truck cranes are used for the tension beams of the badminton hall, and two 220t truck cranes are used for the tension beams of the basketball and volleyball halls. The two truck cranes are respectively positioned on both sides of the span direction of the tension beams, with one crane on each of the east and west sides of the stadium, forming a dual-crane lifting configuration. Before lifting, the trenches surrounding the stadium structure have been backfilled, providing the foundation bearing capacity for the truck cranes to stand and rotate.

[0065] Before the formal lifting of the tensioned beam, a trial lifting procedure is performed. The trial lifting height does not exceed the preset trial lifting height, which is set to 200mm in this embodiment. Two cranes simultaneously lift the hooks according to the lifting instructions of the unified command signal system, slowly raising the tensioned beam to a height of about 200mm from the support surface of the jig, then pausing the lifting and locking the winch mechanism to make the tensioned beam stably suspended at this height. In the trial lifting and suspension state, a comprehensive inspection of the connection status of the hanger is carried out: check whether the pin connection between the middle vertical rod of the hanger and the upper chord of the tensioned beam is tight and not loose, and whether the safety pin or limit device of the pin is installed in place and effective; check whether the connecting pin or shackle between the upper lifting point of the hanger and the lower end of the sling is locked reliably; check whether there are any abnormal deformations or weld cracks visible to the naked eye at each member of the hanger, the reinforcing plate, and the node plate. Simultaneously, the braking performance of the two cranes was tested: While suspended, the hoisting brakes and luffing brakes of each crane were inspected and pressure-held to confirm that there was no hook slippage or dragging, and that the braking distance met safety requirements. Furthermore, the synchronous response of the two cranes was verified: under the unified command of the general commander, micro-lifting and micro-lowering commands were simultaneously sent to both cranes. The synchronization of height changes at both ends of the tension beam was observed and measured to confirm that the time difference in the action delay of the two cranes to the same command was within an acceptable range, and the difference in lifting speed did not exceed the preset threshold of 0.1 m / s. If any test item was found to be unsafe during the trial lifting, the tension beam was immediately lowered back to the jig, the problem was investigated and eliminated, and the trial lifting was repeated until all test items passed before proceeding to the formal lifting procedure.

[0066] The following describes the complete implementation of the present invention using the hoisting and construction process of a typical tensioned beam ZXL-4 in a badminton hall as an example.

[0067] In this embodiment, the tensioned beam ZXL-4 to be hoisted is located in the badminton hall area of ​​the gymnasium, with a structural span of 50.4m. It is a variable-height, polygonal tensioned beam. Its upper chord has a rectangular box section with dimensions of 800×350×25×28mm, i.e., a section height of 800mm, a section width of 350mm, a flange thickness of 28mm, and a web thickness of 25mm. The steel material is Q420B. The struts are made of φ250×16mm round tubes, made of Q355B steel. The lower chord is equipped with prestressed high-vanadium cables with a diameter of φ100mm. The total weight of the entire tensioned beam, including the prestressed cables, is approximately 35.5t. The weight of the hoisting slings is calculated at 1.5t, resulting in a total lifting load of 37.0t.

[0068] Prior to the hoisting operation, the tensioned beam had been assembled in sections on the ground on the assembly jig on the second-floor concrete floor of the stadium, in its original vertical assembly state, with the cables approximately 200mm above the ground. After assembly, the cables were initially tensioned to 10% of the design tension, with an initial tension of 80kN for this beam. This pre-tension ensured that the deformation of the tensioned beam was controllable during subsequent hoisting, achieving a permanent-temporary connection. Slippage of the end supports of the tensioned beam was permitted during the hoisting phase. The trenches surrounding the stadium structure had been backfilled, providing a suitable location for the truck crane.

[0069] Step S10 is executed to obtain the key structural parameters of the tensioned beam, including the span of 50.4m, the height of the upper chord section of 800mm, the section width of 350mm, the wall thickness of 25mm and 28mm, and the slenderness ratio λy calculated from the overall model. Based on the above parameters, an integrated mechanical model of the eccentric compression-bending member is established in the Midas Gen finite element numerical analysis platform. The tensioned beam is discretized into spatial beam elements to simulate its variable-height polygonal structural morphology, box-section characteristics, constitutive relation of Q420B steel, and lifting boundary conditions with simply supported ends. The applied load is the structural self-weight considering the dynamic amplification effect, with a partial factor of 1.3 and a dynamic factor of 1.4, forming the load design values ​​for strength and stability verification. Through model analysis, the axial force N under the hoisting state is estimated to be 380.7kN, the bending moment M is 859.8kN·m, and the eccentricity e = M / N = 2.26m is calculated. With maximizing the out-of-plane stability coefficient as the primary optimization objective and minimizing the mid-span bending moment as the secondary optimization objective, and with the constraint that the local compressive stress at the lifting points does not exceed the compressive strength of Q420B steel, the position coordinates of the two lifting points along the axis of the upper chord were iteratively calculated. After dozens of iterations, the results converged to the optimal position coordinates. Taking the center of gravity as the reference, the distance between the first lifting point and the center of gravity is 18.15m, and the distance between the second lifting point and the center of gravity is 18.95m, with a distance of 37.1m between the two lifting points. Calculations showed that the out-of-plane stability stress ratio of the tensioned beam at this lifting point position is 0.830, which is not greater than 1.0, meeting the code requirements.

[0070] In step S20, at the two suspension points calculated in step S10 on the upper chord of the tensioned beam, two hangers are fixed below each suspension point. The upper crossbars of the two hangers below the same suspension point are fixedly connected by a horizontal connecting rod. The main body of the hanger is made of double-splittered [25b channel steel, with an overall length of approximately 1.8m. The top of the channel steel is connected by HW200×200×8×12 steel. Pin holes are opened at the web of the channel steel, and 10mm thick reinforcing plates are added on both sides. 10.9 grade φ80mm diameter pins are passed through the pin holes and fastened to the double lifting lugs pre-welded and fixed to the side of the upper chord. The lifting lugs are 20mm thick and made of Q355B material. The top of the hanger uses φ180×6mm round tubes as horizontal supports, and the two ends of the supports are connected to the hanger by 8.8 grade M22 bolts. After the hanger is fixed, its upper lifting point is located above the center of gravity of the tensioned beam section, so that the point of application of the lifting force is transferred from below the center of gravity of the component to above the center of gravity of the component.

[0071] In step S30, each of the two 300t truck cranes is connected to a corresponding lifting point using slings. Each lifting point is connected to two upper lifting points on two supports below it via two slings. The lower ends of the slings are connected to the upper lifting point holes on the top of the supports via shackles. The upper ends of the two slings converge to form a lifting point, which is then attached to the truck crane hook. This lifting point, along with the two upper lifting points, forms a triangular force transmission configuration in space. The two 300t truck cranes are of the same model and have the same performance parameters, positioned on the east and west sides of the stadium respectively, forming a dual-crane lifting configuration. Both truck cranes have a boom length of 45.1m. The first truck crane has a working radius of 28m and a rated lifting capacity of 25.8t; the second truck crane has a working radius of 30m and a rated lifting capacity of 24.2t.

[0072] Perform step S40 to calculate the load distribution between the two cranes. Using the center of gravity position calculated by the Midas Gen model in step S10 as the moment center, the first horizontal distance d1 from the center of gravity to the first lifting point is measured along the upper chord axis as 18.15m, and the second horizontal distance d2 to the second lifting point is measured as 18.95m. Establish the moment balance equation: First crane load F1 × 18.15 = Second crane load F2 × 18.95, and F1 + F2 = 37.0t. Solving for F1, we get F1 = 18.9t and F2 = 18.1t. Perform a safety check on the load distribution: The lifting capacity of the first truck crane reduced to 80% is 20.6t, which is greater than 18.9t; the lifting capacity of the second truck crane reduced to 80% is 19.4t, which is greater than 18.1t; 75% of the total allowable lifting capacity of the two truck cranes is 37.5t, which is greater than 37.0t. All three indicators meet the safety requirements.

[0073] Execute step S50 to conduct a trial lift before the formal lifting. Two truck cranes simultaneously lift the cable beam according to a unified command signal, slowly raising it to a height of approximately 200mm above the support surface of the jig, then suspending it. The preset trial lift height is 200mm. While suspended, check the tightness of all pin connections on the lifting frame, ensure the safety pins are properly installed, and inspect all members, reinforcing plates, and welds for abnormal deformation or cracks. Check the brake pressure of both truck cranes to confirm there is no hook slippage or slippage. Send small lifting and lowering commands, observing whether the height changes at both ends of the cable beam are synchronized, confirming that the difference in lifting speed between the two truck cranes does not exceed 0.1m / s. After all inspection items pass, lower the cable beam back to the jig, preparing for the formal lifting.

[0074] Continue with step S50 to control the synchronous lifting of the two truck cranes. The chief commander sends lifting commands to both crane operators simultaneously via walkie-talkie, maintaining consistent hoisting speeds and keeping the speed difference within a preset threshold of 0.1 m / s. During lifting, long rulers installed at both ends of the tension beam, in conjunction with a level, monitor the height deviation in real time. Simultaneously, load sensors installed at the hooks of both cranes measure the actual load value in real time. In this embodiment, the preset height deviation threshold is 50 mm, and the preset load deviation threshold is ±10% of the design load distribution value, meaning the allowable load range for the first crane is 17.01 t to 20.79 t, and the allowable load range for the second crane is 16.29 t to 19.91 t. When the crane was raised to a height of approximately 3 meters, it was observed that the first end of the tension beam was about 65 mm higher than the second end, exceeding the 50 mm height deviation threshold. The commander immediately issued a stop order, controlling the first mobile crane on the higher side to descend slightly. Synchronous lifting resumed after the height deviation returned to within 50 mm. When the crane was raised to a height of approximately 8 meters, the load sensor showed that the actual load on the first mobile crane was 21.2 t, exceeding the upper limit of the load distribution value of 18.9 t by 20.79 t (+10%). The commander immediately stopped the first mobile crane from lifting, and the second mobile crane was raised slightly to adjust the load difference. Synchronous lifting of both cranes resumed after the load difference returned to within ±10%.

[0075] In step S60, after the tensioned beam is raised to the design elevation above the column top, two truck cranes are positioned smoothly and the winch mechanism is locked. Construction personnel accurately align the base plates of the support at both ends of the tensioned beam with the pre-embedded fixed hinge supports at the column top, insert the connecting bolts, and tighten them symmetrically in steps according to the design torque value, completing the reliable fixation of the tensioned beam to the main structure. After the tensioned beam is fixed in place, a tower crane is used to promptly install the three connecting secondary beams between the tensioned beams. The connecting node plates of the secondary beams to the upper chord of the tensioned beam are fixed with bolts to ensure the lateral stability of the tensioned beam after the sling restraints are released. After the connecting secondary beams are installed, the hooks of the two truck cranes are slightly lowered to change the slings from a stressed state to a relaxed state. Construction personnel remove the connecting shackles between the upper lifting point and the slings, releasing the force transmission path between the crane and the gantry; remove the pin between the middle vertical rod of the gantry and the lifting lug plate of the upper chord of the tensioned beam, and move the entire gantry away from the upper chord, transporting it to the ground for storage. The two 300t truck cranes were removed from the site, marking the completion of the hoisting operation for the tensioned beam.

[0076] Repeat steps S10 to S60 to complete the hoisting of a total of 12 tensioned beams, including 6 for the badminton hall and 6 for the basketball / volleyball hall. After all tensioned beams are in place and the secondary beams are installed, perform secondary tensioning according to the design requirements until the cable force reaches 100%, fix the hinge supports, and complete the construction of the entire tensioned beam roof.

[0077] like Figures 2-4 As shown, a tensioned beam hoisting device according to a second embodiment of the present invention is used to execute a hoisting method based on tensioned beam size parameters according to a first embodiment, including: Four 100mm hangers are arranged in groups of two 100mm hangers, and are placed below two hanging points. Each hanger 100 is composed of two parallel and spaced vertical rods 110. The upper ends of the two vertical rods 110 are fixedly connected by an upper horizontal rod 120. The upper horizontal rod 120 is provided with an upper end suspension point 121 for connecting to the lower end of the sling wire rope 300. Each of the vertical rods 110 has a pin hole at its middle end, the pin hole being used for a pin 140 to pass through to connect the vertical rod 110 to the lug plate 150 fixed on the upper chord of the tension beam; A reinforcing plate 160 is fixedly provided on each vertical rod 110. The reinforcing plate 160 is attached to the surface of the vertical rod 110. The pin hole passes through the reinforcing plate 160. The surface area of ​​the reinforcing plate 160 is larger than the hole area of ​​the pin hole. The upper crossbars 120 of two hangers 100 connected to the same crane are fixedly connected by a horizontal connecting rod 200, and the two ends of the horizontal connecting rod 200 are respectively fixedly connected to the upper crossbars 120 of the two hangers 100. Each crane is equipped with two sling wire ropes 300. The upper ends of the two sling wire ropes 300 meet at one point to form a lifting point 310. The lower ends of the sling wire ropes 300 are respectively connected to the upper lifting point 121 of the corresponding hanger 100. The vertical line of the lifting point 310 passes through the midpoint of the horizontal connecting rod 200.

[0078] In this embodiment, the device further includes a height deviation sensor, a load sensor, and a control device. The height deviation sensor is installed at both ends of the tensioned beam to acquire the height deviation value at both ends of the tensioned beam during the lifting process. The load sensor is installed on the hooks or slings of the two cranes to acquire the actual load value of the two cranes during the lifting process. The control device is communicatively connected to the height deviation sensor and the load sensor, and electrically connected to the crane's lifting control system. It receives the height deviation value and the actual load value, and when it determines that the height deviation value exceeds a preset height deviation threshold or the difference between the actual load value and the load distribution exceeds a preset load deviation threshold, it sends a lifting speed adjustment command to the corresponding crane's lifting control system.

[0079] See Figure 2 and Figure 3 In this embodiment, the vertical rod 110 is made of double-layered 25b channel steel, with the two channel steels arranged back-to-back, leaving a gap between them for the insertion of the lifting lug plate 150. The upper ends of the two vertical rods 110 are fixedly connected by an upper horizontal rod 120. The connection between the vertical rod 110 and the upper horizontal rod 120 is fixed by welding, forming a rectangular frame structure. The upper horizontal rod 120 is provided with an upper lifting point 121 for connecting to the lower end of the sling wire rope 300. In this embodiment, the upper lifting point 121 is formed by opening a through pin hole on the web of the double-layered channel steel and welding a reinforcing plate 160, for the pin or shackle to pass through to connect to the lower end of the sling wire rope 300.

[0080] Each vertical rod 110 has a pin hole at its middle end, located slightly above the middle along its length. This pin hole allows a pin 140 to pass through, connecting the vertical rod 110 to a lug plate 150 pre-welded and fixed to the side or top of the upper chord of the tensioned beam. In this embodiment, the design diameter of the pin hole is determined based on the diameter of the selected pin 140, which is a 10.9 grade φ80mm high-strength pin. The diameter of the pin hole matches this diameter while maintaining an appropriate assembly clearance. The lug plate 150 is 20mm thick, made of Q355B material, and pre-welded and fixed to the corresponding suspension point position of the upper chord of the tensioned beam. The lug plate 150 also has through holes corresponding to the pin holes. During installation, the pin holes of the vertical rod 110 are aligned with the through holes of the lug plate 150, the pin 140 is inserted, and a safety pin or limiting device is installed to achieve a reliable force transmission connection between the hanger 100 and the upper chord of the tensioned beam.

[0081] A reinforcing plate 160 is fixedly installed on each vertical rod 110. The reinforcing plate 160 is attached to the outer surface of the vertical rod 110. In this embodiment, the reinforcing plate 160 is 10mm thick and is made of the same material as the 25b channel steel of the main body of the vertical rod 110 or a steel with matching strength. The reinforcing plate 160 is welded to the surface of the vertical rod 110 by fillet welds or multiple continuous fillet welds, and the weld quality meets the secondary weld standard. The pin hole penetrates the reinforcing plate 160, that is, the reinforcing plate 160 has a hole concentric with the pin hole of the vertical rod 110 and of the same diameter, forming a double-walled pin connection structure. The surface area of ​​the reinforcing plate 160 is larger than the hole area of ​​the pin hole. Specifically, the side length or diameter of the reinforcing plate 160 is at least three times the diameter of the pin hole, so as to form a sufficient stress diffusion area around the pin hole, effectively reduce the peak value of the extrusion stress at the edge of the hole, and prevent local plastic deformation or tearing damage of the peripheral wall of the pin hole under the action of hoisting load.

[0082] The upper crossbars 120 of two hangers 100 connected to the same crane are fixedly connected by a horizontal connecting rod 200. Both ends of the horizontal connecting rod 200 are fixedly connected to the upper crossbars 120 of the two hangers 100, respectively. In this embodiment, the horizontal connecting rod 200 is made of a φ180×6mm round tube, and both ends are detachably connected to the pre-set bolt holes on the upper crossbars 120 of the two hangers 100 using 8.8 grade M22 bolts. The horizontal connecting rod 200 connects the two hangers 100 connected to the same crane into a single spatial structure, enhancing the overall stiffness and lateral stability of the hanger 100 system in the direction of the tension beam axis, and effectively constraining the relative displacement or torsion that may occur between the two hangers during use. A stiffening plate with a thickness of 20mm and made of Q235B is welded at the connection node to enhance the local stiffness of the bolted connection node.

[0083] See Figure 4 Each crane is equipped with two sling wire ropes 300. The upper ends of the two sling wire ropes 300 meet at one point to form a lifting point 310, and the lower ends of the sling wire ropes 300 are respectively connected to the upper lifting points 121 of the corresponding hangers 100. In this embodiment, the two sling wire ropes 300 are of equal length so that the vertical line of the lifting point 310 passes through the midpoint of the line connecting the two corresponding upper lifting points 121. This midpoint is also the midpoint of the horizontal connecting rod 200, ensuring that the two sling wire ropes 300 transmit force symmetrically and that the hangers 100 are subjected to balanced forces.

[0084] Furthermore, the tensioned beam hoisting device in this embodiment also includes a height deviation sensing device, a load sensing device, and a control device. The height deviation sensing device is installed at both ends of the tensioned beam. In this embodiment, it is implemented using a laser rangefinder or a level in conjunction with a measuring rod. The laser rangefinder is fixed to the top surface of the upper chord at both ends of the tensioned beam. By continuously measuring the distance from a fixed reference point on the ground, the height difference between the two ends is calculated. Alternatively, a level is set up on the ground, and observers read the scale values ​​of the measuring rods at both ends of the tensioned beam to obtain the height deviation value. The measurement accuracy of the height deviation sensing device is not less than 5mm, and the sampling frequency is not less than 1Hz to meet the engineering requirements for real-time monitoring.

[0085] The load sensing device is installed on the hooks or slings of the two cranes. In this embodiment, a pin-type load cell or an S-type tension sensor is preferably used in series in the force transmission path between the hook and the sling to convert the actual tension borne by the sling during the lifting process into an electrical signal output. The range of the load sensing device is selected according to the rated lifting capacity of the crane. Taking a 300t truck crane used in a badminton hall as an example, the sensor range is not less than 50t, and the measurement accuracy is not less than 0.5% of the full scale, which can accurately reflect the small changes within ±10% of the load distribution value.

[0086] The control device is communicatively connected to the height deviation sensor and the load sensor. Communication is achieved via wired signal transmission or an industrial wireless data transmission module. In this embodiment, a wired transmission method with strong anti-interference capabilities is preferred. The signal line is laid along the slings and fixed, connecting to a control cabinet located on the ground. The control device is electrically connected to the hoisting control systems of the two cranes, using the crane's own pre-installed control interface or an additional electrical control switching module. During hoisting, the control device continuously receives the height deviation value collected by the height deviation sensor and the actual load value collected by the load sensor. It compares the height deviation value with a preset height deviation threshold of 50mm and the difference between the actual load value and the load distribution value with a preset load deviation threshold of ±10%.

[0087] When the height deviation exceeds a threshold of 50mm, the control device automatically sends a lifting speed adjustment command to the lifting control system of the crane on the higher or lower side, controlling the higher crane to reduce its lifting speed or suspend lifting, and / or controlling the lower crane to increase its lifting speed. When the difference between the actual load value and the load distribution value exceeds a threshold of ±10%, the control device automatically sends a command to the crane with the larger actual load value to reduce its lifting speed or suspend lifting. After all deviation values ​​return to the corresponding threshold range, the control device sends a command to both cranes to resume synchronous lifting. Through the above-mentioned automated signal acquisition, logic judgment, and control output, a closed-loop control system for the synchronous lifting state of the two cranes is constructed, effectively improving the accuracy and responsiveness of synchronous control.

[0088] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process and related explanations of the methods described above can be found in the corresponding processes in the foregoing system embodiments, and will not be repeated here.

[0089] The terms “first”, “second”, etc., are used to distinguish similar objects, not to describe or indicate a specific order or sequence.

[0090] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0091] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method of hoisting based on beam string dimension parameters, characterized by, include: The span, cross-sectional dimensions, and slenderness ratio of the tensioned beam are obtained. With the goal of maximizing the out-of-plane stability coefficient and minimizing the mid-span bending moment, and with the constraint that the local compressive stress at the suspension point does not exceed the compressive strength of the steel, the spatial positions of the two suspension points are calculated. Two hangers are fixed below each of the above-mentioned suspension points on the upper chord of the tensioned beam. The two hangers below the same suspension point are fixedly connected by a horizontal connecting rod. The middle part of the hanger is connected to the upper chord of the tensioned beam, and the upper suspension point of the hanger is located above the centroid of the tensioned beam section. Two cranes are each connected to a corresponding lifting point via slings. The lifting point of each crane is connected to the upper lifting points of two hangers below the lifting point via two sling wire ropes, so that the lifting point and the two upper lifting points form a triangular force transmission configuration. Obtain the center of gravity position of the tension beam, and calculate the load distribution between the two cranes based on the obtained center of gravity position and the horizontal distance between the two lifting points. Two cranes are controlled to lift synchronously. During the lifting process, the height deviation value at both ends of the tension beam and the actual load value of the two cranes are obtained. When the obtained height deviation value exceeds the preset height deviation threshold, or the difference between the obtained actual load value and the load distribution exceeds the preset load deviation threshold, the lifting speed of at least one crane is adjusted so that the height deviation value and the difference are restored to the corresponding threshold range. After the tension beam is hoisted into place, fix the tension beam and remove the hanger.

2. The method of claim 1, wherein, Obtain the span, cross-sectional dimensions, and slenderness ratio of the tensioned beam, and calculate the locations of the two suspension points, including: Obtain the parameters of the tensioned beam, including the span value, the height value of the upper chord section, the width value of the upper chord section, the wall thickness value of the upper chord, and the slenderness ratio value; A mechanical model of the eccentric compression-bending member is established based on the obtained parameters. The estimated axial force and estimated bending moment under the hoisting state are calculated in the mechanical model, and the eccentricity is calculated based on the estimated axial force and estimated bending moment. Using the out-of-plane stability coefficient as the first optimization objective, the mid-span bending moment as the second optimization objective, and the constraint that the local compressive stress at the lifting point does not exceed the compressive strength of the upper chord steel, the position coordinates of the two lifting points in the direction of the upper chord axis are iteratively calculated to obtain the positions of the two lifting points.

3. The method according to claim 1, characterized in that, Obtain the center of gravity position of the tension beam, and calculate the load distribution between the two cranes based on the obtained center of gravity position and the distance between the two lifting points, including: The crane connected to one lifting point is designated as the first crane, and the crane connected to the other lifting point is designated as the second crane. The lifting point connected to the first crane is designated as the first lifting point, and the lifting point connected to the second crane is designated as the second lifting point. Using the obtained center of gravity position as the torque center, measure the first horizontal distance from the center of gravity position to the first lifting point, and the second horizontal distance from the center of gravity position to the second lifting point; Obtain the total lifting weight of the tensioned beam and the weight of the lifting slings; Establish a moment balance equation, such that the product of the vertical component of the load borne by the first crane and the first horizontal distance is equal to the product of the vertical component of the load borne by the second crane and the second horizontal distance, and the sum of the vertical components of the load borne by the first crane and the second crane is equal to the sum of the total lifting weight and the weight of the slings. Solve the torque balance equation to obtain the load distribution of the first crane and the second crane respectively.

4. The method according to claim 1, characterized in that, Controlling the synchronous lifting of two cranes includes: The hoisting command is sent to both cranes simultaneously through a unified command signal system. During each hoisting phase, the hoisting speed of the two cranes is kept consistent, and the difference in hoisting speed does not exceed the preset speed difference threshold.

5. The method according to claim 1 or 4, characterized in that, Adjusting the lifting speed of at least one crane, including: When the height deviation value exceeds the height deviation threshold, the crane on the higher side is controlled to reduce its lifting speed or suspend lifting, and / or the crane on the lower side is controlled to increase its lifting speed. When the difference exceeds the load deviation threshold, the crane on the side with the larger actual load value is controlled to reduce its lifting speed or suspend lifting. Once the height deviation value returns to the height deviation threshold range and the difference returns to the load deviation threshold range, the two cranes resume synchronous lifting.

6. The method according to claim 1, characterized in that, The method is performed after the tensioned beam is assembled and initially tensioned. The tensioned beam is a variable-height polygonal tensioned beam with a rectangular cross-section for the upper chord. Prestressed cables are installed below the tensioned beam. The two cranes are two truck cranes of the same model and lifting performance parameters, which are respectively set on both sides of the span direction of the tensioned beam for dual-crane lifting.

7. The method according to claim 1, characterized in that, The method further includes: Before lifting the tension beam, a trial lift is performed on the tension beam. The trial lift height does not exceed the preset trial lift height. During the trial lift, the connection status of the suspension frame, the braking performance of the two cranes, and the synchronization response status are checked.

8. The method according to claim 1, characterized in that, The upper lifting point of the sling is connected to the lower end of the sling through a pin-type connection structure, and the upper end of the sling is connected to the crane hook.

9. A tensioned beam hoisting device for implementing the method according to any one of claims 1 to 7, characterized in that, include: Four hangers are arranged in pairs below two hanging points. Each hanger consists of two parallel and spaced vertical bars, the upper ends of which are fixedly connected by an upper horizontal bar, which is provided with an upper lifting point for connecting to the lower end of the sling wire rope; Each of the vertical rods has a pin hole at its middle end, through which a pin passes to connect the vertical rod to a lug plate pre-fixed to the upper chord of the tension beam. A reinforcing plate is fixedly installed on each vertical rod. The reinforcing plate is fixed to the surface of the vertical rod. The pin hole passes through the reinforcing plate. The surface area of ​​the reinforcing plate is larger than the hole area of ​​the pin hole. The upper crossbars of two hangers connected to the same crane are fixedly connected by a horizontal connecting rod; Each crane is equipped with two sling wire ropes. The upper ends of the two sling wire ropes meet at one point to form the lifting point, and the lower ends of the sling wire ropes are respectively connected to the upper lifting point of the corresponding crane frame.

10. The apparatus according to claim 9, characterized in that, Also includes: A height deviation sensor is installed at both ends of the tensioned beam to obtain the height deviation value at both ends of the tensioned beam during the lifting process. Load sensing devices are installed on the hooks or slings of two cranes to obtain the actual load values ​​of the two cranes during the lifting process. The control device is communicatively connected to the height deviation sensing device and the load sensing device, and electrically connected to the hoisting control system of the crane. It is used to receive the height deviation value and the actual load value, and when it is determined that the height deviation value exceeds a preset height deviation threshold or the difference between the actual load value and the load distribution exceeds a preset load deviation threshold, it sends a hoisting speed adjustment command to the hoisting control system of the corresponding crane.

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