An Optimized Design and Stress Calculation Method for Lifting Points of Ultra-Long Steel Cages

Abstract

This application relates to an optimized design and stress calculation method for lifting points of ultra-long steel cages, belonging to the technical field of foundation underground structure construction. The method includes the following steps: establishing a total coordinate system and two local coordinate systems for the lifting points of the steel cage, applicable to four-point lifting of the steel cage; performing individual stress calculations based on each segment of the two wire ropes branching at their bottom; and combining the motion trajectory calculations of the wire rope branching points. First, the reaction force at each lifting point is calculated, then the bending moment at each lifting point is calculated. The point with the smallest absolute value of the maximum positive and negative bending moments obtained algebraically is the optimal lifting point. This application improves the speed and accuracy of calculating the bending moment value during the rotation of the steel cage lifting point.

Description

Technical Field

[0001] This application relates to the technical field of underground foundation construction, and in particular to an optimized design and stress calculation method for the hoisting points of ultra-long steel cages. Background Technology

[0002] In the construction of foundation underground structures, the main function of the reinforcing cage is similar to that of the longitudinal reinforcement in columns, primarily acting as a tensile force. Concrete has high compressive strength but very low tensile strength. The reinforcing cage restrains the concrete of the pile body, enabling it to withstand a certain axial tensile force. In actual construction, piles are driven according to the foundation requirements, using machine-drilled and water-jet-driven holes to achieve the design depth. The reinforcing cage is then lowered into the pile hole, and a tremie pipe is inserted for concrete pouring.

[0003] The construction of reinforcing cages requires hoisting, which is divided into two stages: horizontal hoisting and rotational hoisting. The maximum internal force directly determines the strength of the reinforcing cage and the reinforcement arrangement. For multi-point hoisting, the rotational stress situation is more dangerous than the horizontal hoisting stage. Therefore, optimizing the hoisting nodes to obtain the optimal hoisting point has high practical value.

[0004] Definition of optimal lifting point: During the hoisting process of a steel cage, for rotary hoisting, the absolute value of the maximum positive and negative bending moment of each dangerous section of the steel cage is minimized throughout the entire rotation process; for horizontal hoisting, the absolute value of the maximum positive and negative bending moment of each dangerous section of the steel cage is equal or similar. At the same time, the extreme value of the column bending moment should meet the requirements of strength and crack resistance. Such a lifting point position is the optimal lifting point, which is also the design principle of the optimal lifting point.

[0005] When a reinforcing cage is rotated and hoisted, the extreme bending moments at various critical sections of the cage may occur during the horizontal hoisting phase or during the rotation phase. Therefore, when determining the optimal hoisting point for a reinforcing cage, the extreme bending moment should be minimized throughout the entire rotation process. However, existing methods for calculating the bending moment during rotation at the hoisting point of a reinforcing cage are slow and inaccurate. Summary of the Invention

[0006] To improve the speed and accuracy of calculating the bending moment value when the lifting point of the steel cage rotates, this application provides an optimized design and stress calculation method for the lifting point of an ultra-long steel cage.

[0007] The technical solution provided in this application for an optimized design and stress calculation method for lifting points of ultra-long steel cages is as follows:

[0008] A method for optimizing the design and stress calculation of lifting points for ultra-long steel cages includes the following steps:

[0009] Establish a general coordinate system for the hoisting points of the reinforcing cage, with one end of the reinforcing cage as the origin o, the horizontal direction as the x-axis, and the vertical direction as the y-axis. There are two steel wire ropes of lengths L1 and L2, each divided into two sections at the bottom, resulting in a total of four hoisting points. The steel wire rope of length L1 has a bifurcation point e and two hoisting points a and b; the steel wire rope of length L2 has a bifurcation point f and two hoisting points c and d. Based on the two steel wire ropes, establish two local coordinate systems for the hoisting points of the reinforcing cage, with a and c as the origins respectively, the horizontal direction as the x-axis, and the vertical direction as the y-axis.

[0010] The length of the steel cage is l, the weight of the steel cage is G, and the tensions of the wire ropes ae, be, cf, and df are F1, F2, F3, and F4, respectively. During the hoisting process, points e and f are moving points, and the tensions of the same rope are equal. Fa and Fc are used to represent the tensions of ropes aeb and cfd, respectively, i.e., F1 = F2 = Fa, F3 = F4 = Fc. γ is the rotation angle of the steel cage, and θ1 and θ2 are the angles between ropes ae and cf and the x-axis, i.e., the angles between the ropes and the horizontal ground.

[0011] During the reversal process, the lengths of ropes aeb and cfd remain constant. The trajectories of moving points e and f are ellipses with foci a and b, c and d as foci. Let the length of ae be Lae and the length of ab be Lab.

[0012] Based on geometric relationships and the Law of Cosines:

[0013]

[0014] Let the length of cf be Lcf, and the length of cd be Lcd. Similarly, we can obtain:

[0015]

[0016] Let the length of the reinforcing cage between the origin o and the lifting point a be c1l, the length between lifting point a and b be c2l, the length between lifting point b and c be c3l, the length between lifting point c and d be c4l, and the remaining length of the reinforcing cage after lifting point d be c5l; the resultant force of the wire rope of length L1 be R1, and the resultant force of the wire rope of length L2 be R2. According to the moment balance, the equilibrium equation at point d is:

[0017] R1[(c2+c3)l cosγ-L ae cosθ1+L cf cosθ2]=G[(c1+c2+c3-0.5)l cosγ+L cf cosθ2]

[0018]

[0019] The resultant force R2 of the rope is:

[0020] R2 = G - R1

[0021] Based on the force conditions of the two wire ropes, we can conclude that:

[0022]

[0023]

[0024] The reactions at suspension points a and b are:

[0025]

[0026]

[0027] The reaction forces at suspension points c and d are:

[0028]

[0029]

[0030] The distance from the location of minimum shear force (shear force is zero) in each span to the fixed point O of the reinforcing cage is: span ab:

[0031]

[0032] bc cross:

[0033]

[0034] cd span:

[0035]

[0036] The maximum bending moment in each span (ab, bc, cd) is:

[0037]

[0038]

[0039]

[0040] in:

[0041] c5 = 1 - c1 - c2 - c3 - c4

[0042] The bending moments at each lifting point (a, b, c, d) are respectively

[0043]

[0044]

[0045]

[0046]

[0047] By adopting the above technical solution, a total coordinate system for the rebar cage hoisting point and two local coordinate systems for the rebar cage hoisting point are established. This is applicable to the four-point hoisting of the rebar cage. The stress calculation is performed on each segment of the two wire ropes that branch off at the bottom. Combined with the motion trajectory calculation of the wire rope branching point, the reaction force of each hoisting point is calculated first, and then the bending moment of each hoisting point is calculated. The point with the smallest absolute value of the maximum positive and negative bending moment obtained by algebra is the optimal hoisting point. This improves the speed and accuracy of the calculation of the bending moment value when the rebar cage hoisting point rotates.

[0048] Optionally, when the reinforcing cage is only horizontally hoisted, without considering the change in the extreme value of the bending moment during the rotation stage, the optimal hoisting point is determined by the fact that the absolute values ​​of the maximum positive and negative bending moments of each major critical section of the pile body are equal when it is in a horizontal position. The combined control equation is:

[0049] By adopting the above technical solution, the bending moment extreme value of this combined control equation is minimized, making it more suitable for calculating the optimal lifting point in the horizontal hoisting stage.

[0050] Optionally, the connection structure at each lifting point of the reinforcing cage includes a hook device for hooking onto the outer ring reinforcing bars of the reinforcing cage and several limiting strips fixed to the outer ring reinforcing bars of the reinforcing cage. The hook device is located between two adjacent limiting strips to determine the position of the lifting point. The hook device includes a connecting block, an arc-shaped hook plate, a driving mechanism, and an anti-detachment mechanism. The top of the connecting block is connected to the bottom end of the wire rope. There are two arc-shaped hook plates, which are arranged opposite each other and are hinged to the bottom of the connecting block. The driving mechanism is installed on the connecting block and is used to simultaneously drive the two arc-shaped hook plates to rotate in opposite directions to hook the outer ring reinforcing bars of the reinforcing cage. The anti-detachment mechanism is installed on the connecting block and is used to fix the two arc-shaped hook plates after hooking the outer ring reinforcing bars of the reinforcing cage.

[0051] By adopting the above technical solution, during the hoisting of the rebar cage, two arc-shaped hook plates descend to both sides of the hoisting point of the outer ring rebar of the rebar cage. The driving mechanism causes the two arc-shaped hook plates to rotate relative to each other, forming a closed loop below the outer ring rebar of the rebar cage. The anti-detachment mechanism then fixes the position of the two arc-shaped hook plates. In addition, two limit strips limit the position of the hooks, making the connection of the hoisting point more stable after the rebar cage is hoisted, thus improving the accuracy of the calculation data and the safety of construction.

[0052] Optionally, the bottom of the connecting block is equipped with a lifting plate, which is located in the middle of two arc-shaped hook plates. An arc-shaped pressure plate for pressing the outer ring of the steel cage is fixed at the bottom of the lifting plate. The driving mechanism drives the arc-shaped hook plates to rotate in opposite directions while also driving the lifting plate to descend.

[0053] By adopting the above technical solution, the driving mechanism drives the two arc-shaped hook plates to rotate while the lifting plate descends until the arc-shaped pressure plate presses down on the hoisting point of the outer ring reinforcement of the steel cage, which further improves the safety of the steel cage and the stability of the hoisting point during hoisting.

[0054] Optionally, the drive mechanism includes a drive motor, a first rotating shaft, sprockets, a chain, a second rotating shaft, reversing gears, and a linkage assembly. There are three first rotating shafts, all horizontally rotatably connected to the connecting block. Two of the first rotating shafts are located near the ends of the connecting block, and the third is located above the two first rotating shafts. The drive motor is fixed to one side of the connecting block and coaxially fixed to one of the first rotating shafts. There are three sprockets, each coaxially fixed to its corresponding first rotating shaft, and the chain meshes with the three sprockets. The second rotating shaft is horizontally rotatably connected inside the connecting block and located to one side of one of the lower first rotating shafts. There are two reversing gears, each coaxially fixed to its corresponding first and second rotating shafts, and the two reversing gears mesh with each other. One arc-shaped hook plate is fixed to the second rotating shaft, and the other arc-shaped hook plate is fixed to the lower first rotating shaft away from the second rotating shaft. The linkage assembly is located between the upper first rotating shaft and the lifting plate, and is used to drive the lifting plate to move up and down when the first rotating shaft rotates.

[0055] By adopting the above technical solution, starting the drive motor to rotate one of the first rotating shafts can achieve synchronous rotation of the three first rotating shafts through the sprocket and chain. At this time, the second rotating shaft rotates in the opposite direction relative to the first rotating shaft to achieve relative rotation of the two arc-shaped hook plates. Meanwhile, the upper first rotating shaft drives the lifting plate to descend through the linkage component, so that the hoisting point of the outer ring steel bar of the steel cage is fixed between the arc-shaped pressure plate and the two arc-shaped hook plates, which improves the connection efficiency and operation convenience.

[0056] Optionally, the linkage component includes a linkage gear and a rack. The linkage gear is coaxially fixed with the upper first rotating shaft, and the rack is fixed on one side of the lifting plate. The linkage gear and the rack are always meshed.

[0057] By adopting the above technical solution, the first rotating shaft at the top drives the linkage gear to rotate when it rotates. The linkage gear drives the lifting plate to rise and fall through the rack. The structure is simple and efficient.

[0058] Optionally, the anti-detachment mechanism includes a ratchet, a pawl, and a separation component. The ratchet is fixed to one side of the lifting plate, and the helical teeth of the pawl are inclined upward. The pawl is rotatably connected in the connecting block and engages with the ratchet. The separation component is used to separate the pawl from the ratchet.

[0059] By adopting the above technical solution, when the lifting plate descends, the ratchet follows the lifting plate down, and the pawl is always engaged with the ratchet. This allows the arc-shaped pressure plate to press firmly onto the outer ring of the steel cage, thus automatically fixing the position of the lifting plate. When releasing the hoisting, the pawl is first separated from the ratchet by the separation component, and then the arc-shaped hook plate and the lifting plate can be reset by the drive mechanism, which improves the stability and ease of operation during hoisting.

[0060] Optionally, the separation assembly includes a sliding shaft, a return spring, and a limiting block. The axis of the sliding shaft is parallel to the length direction of the ratchet teeth. The sliding shaft is rotatably connected inside the connecting block and can slide along its own axis. The end of the pawl away from the ratchet is fixed to the sliding shaft. One end of the sliding shaft extends out of the side wall of the connecting block and is fixed to the limiting block. The return spring is fixed between the limiting block and the side wall of the connecting block.

[0061] By adopting the above technical solution, when the lifting is released, the sliding shaft slides when the limit block is pressed. The sliding shaft drives the pawl to move, realizing the separation of the pawl and the ratchet. After the drive mechanism drives the arc hook plate and the lifting plate to reset, the limit block is released, and the reset spring drives the sliding shaft and the pawl to reset, so as to facilitate the next lifting.

[0062] Optionally, each of the arc-shaped hook plates has a gravity block sliding along its own curvature direction on its outer arc surface, and both sides of the gravity block protrude from the sidewall of the arc-shaped hook plate.

[0063] By adopting the above technical solution, when the arc-shaped hook plate rotates, it will cause the gravity block on another arc-shaped hook plate to slide upward, which can make the rotation of the arc-shaped hook plate more stable.

[0064] Optionally, the outer arc surface of the arc hook plate is provided with a T-shaped groove along its own curvature direction, one end of the gravity block is located in the T-shaped groove, and an arc spring is fixed between the inner wall of the T-shaped groove near the bottom of the arc hook plate and the gravity block.

[0065] By adopting the above technical solution, when the arc-shaped hook plate pushes the gravity block on another arc-shaped hook plate upward, the arc-shaped spring is stretched, which further improves the rotational stability of the arc-shaped hook plate; when the arc-shaped hook plate is reset during hoisting, the arc-shaped spring pulls the gravity block to reset, so as to facilitate the next hoisting.

[0066] In summary, this application includes at least one of the following beneficial technical effects:

[0067] 1. During the hoisting of the rebar cage, two arc-shaped hook plates descend to both sides of the hoisting point of the outer ring rebar of the rebar cage. The two arc-shaped hook plates are rotated relative to each other by the drive mechanism to form a closed loop below the outer ring rebar of the rebar cage. The position of the two arc-shaped hook plates is fixed by the anti-detachment mechanism. In addition, two limit strips limit the position of the hooks, which can make the connection of the hoisting point after the rebar cage is hoisted more stable, improve the accuracy of the calculation data and the safety of construction.

[0068] 2. Start the drive motor to make one of the first rotating shafts rotate, and the three first rotating shafts can be rotated synchronously through the sprocket and chain. At this time, the second rotating shaft rotates in the opposite direction relative to the first rotating shaft to realize the relative rotation of the two arc hook plates. At the same time, the upper first rotating shaft drives the lifting plate to descend through the linkage component, so that the hoisting point of the outer ring steel bar of the steel cage is fixed between the arc pressure plate and the two arc hook plates, which improves the connection efficiency and operation convenience.

[0069] 3. When the lifting plate descends, the ratchet follows the lifting plate down, and the pawl is always engaged with the ratchet. This allows the arc-shaped pressure plate to press firmly onto the outer ring of the steel cage, thus automatically fixing the position of the lifting plate. When releasing the hoisting, the pawl is first separated from the ratchet by the separation component, which allows the drive mechanism to reset the arc-shaped hook plate and the lifting plate, improving the stability and ease of operation during hoisting. Attached Figure Description

[0070] Figure 1 This is a coordinate system diagram of Embodiment 1 of this application;

[0071] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of this application;

[0072] Figure 3 This is a schematic diagram of the structure of the T-groove and the arc spring in Embodiment 2;

[0073] Figure 4 This is a vertical sectional view of the display driving mechanism in Embodiment 2;

[0074] Figure 5 This is a cross-sectional view of the display driving mechanism in Embodiment 2;

[0075] Figure 6 This is a schematic diagram of the display driving mechanism in Embodiment 2.

[0076] In the diagram, 1. Limiting strip; 2. Connecting block; 3. Arc-shaped hook plate; 31. T-slot; 32. Gravity block; 33. Arc-shaped spring; 4. Drive mechanism; 41. Drive motor; 42. First rotating shaft; 43. Sprocket; 44. Chain; 45. Second rotating shaft; 46. Reversing gear; 47. Linkage assembly; 471. Linkage gear; 472. Rack; 5. Anti-detachment mechanism; 51. Ratchet; 52. Pawl; 53. Separation assembly; 531. Sliding shaft; 532. Return spring; 533. Limiting block; 6. Lifting plate; 61. Arc-shaped pressure plate. Detailed Implementation

[0077] The following is in conjunction with the appendix Figure 1-6 This application will be described in further detail.

[0078] Example 1

[0079] Embodiment 1 of this application discloses an optimized design and stress calculation method for the hoisting point of an ultra-long steel cage.

[0080] refer to Figure 1 A method for optimizing the design and stress calculation of hoisting points for ultra-long steel cages, comprising the following steps:

[0081] Establish a general coordinate system xoy for the rebar cage hoisting points, with one end of the rebar cage as the origin o, the horizontal direction as the x-axis, and the vertical direction as the y-axis. There are two steel wire ropes of lengths L1 and L2, each divided into two sections at the bottom, resulting in a total of four hoisting points. The steel wire rope of length L1 has a bifurcation point e and two hoisting points a and b; the steel wire rope of length L2 has a bifurcation point f and two hoisting points c and d. Based on the two steel wire ropes, establish two local coordinate systems x1ay1 and x2cy2 for the rebar cage hoisting points, with a and c as the origins, the horizontal direction as the x-axis, and the vertical direction as the y-axis, respectively.

[0082] The length of the steel cage is l, the weight of the steel cage is G, and the tensions of the wire ropes ae, be, cf, and df are F1, F2, F3, and F4, respectively. During the hoisting process, points e and f are moving points, and the tensions of the same rope are equal. Fa and Fc are used to represent the tensions of ropes aeb and cfd, respectively, i.e., F1 = F2 = Fa, F3 = F4 = Fc. γ is the rotation angle of the steel cage, and θ1 and θ2 are the angles between ropes ae and cf and the x-axis, i.e., the angles between the ropes and the horizontal ground.

[0083] During the turning process, the lengths of ropes aeb and cfd remain unchanged. According to the definition of an ellipse, in the local coordinate system x1ay1 and x2cy2, the trajectory of the moving points e and f is an ellipse with foci a and b, c and d. Therefore, in the local coordinate system x1ay1, let the length of ae be Lae and the length of ab be Lab.

[0084] Based on geometric relationships and the Law of Cosines:

[0085]

[0086] Let the length of cf be Lcf, and the length of cd be Lcd. Similarly, we can obtain:

[0087]

[0088] Let the length of the reinforcing cage between the origin o and the lifting point a be c1l, the length between lifting point a and b be c2l, the length between lifting point b and c be c3l, the length between lifting point c and d be c4l, and the remaining length of the reinforcing cage after lifting point d be c5l; the resultant force of the wire rope of length L1 be R1, and the resultant force of the wire rope of length L2 be R2. According to the moment balance, the equilibrium equation at point d is:

[0089] R1[(c2+c3)l cosγ-L ae cosθ1+L cf cosθ2]=G[(c1+c2+c3-0.5)l cosγ+L cf cosθ2]

[0090]

[0091] The resultant force R2 of the rope is:

[0092] R2 = G - R1

[0093] Based on the force conditions of the two wire ropes, we can conclude that:

[0094]

[0095]

[0096] The reactions at suspension points a and b are:

[0097]

[0098] The reaction forces at suspension points c and d are:

[0099]

[0100]

[0101] The distance from the location of minimum shear force (shear force is zero) in each span to the fixed point O of the reinforcing cage is: span ab:

[0102]

[0103] bc cross:

[0104]

[0105] cd span:

[0106]

[0107] The maximum bending moment in each span (ab, bc, cd) is:

[0108]

[0109] in:

[0110] c5 = 1 - c1 - c2 - c3 - c4

[0111] The bending moments at each lifting point (a, b, c, d) are respectively

[0112]

[0113] When the reinforcing cage is only horizontally hoisted, the change in the extreme value of the bending moment during the rotation phase is not considered. The optimal hoisting point for horizontal hoisting is determined by ensuring that the absolute values ​​of the maximum positive and negative bending moments at all major critical sections of the pile are equal when the pile is in a horizontal position. The optimal combination control equation is: Calculations show that the extreme values ​​of bending moments for other combinations are not the minimum.

[0114] When the hoisting is horizontal, γ = 0, and the optimal hoisting point can be obtained as follows:

[0115] c1 = c5 = 0.1036

[0116] c2 = c4 = 0.2929

[0117] c3 = 0.207

[0118] At this point, the reaction forces and constraint positions of the above-mentioned lifting points are symmetrical, which are the optimal lifting points for horizontal lifting. However, each steel cage must be rotated from a horizontal position to be perpendicular to the ground, i.e., γ = γ0 ~ 90°. Therefore, iterative analysis is performed on each angle to obtain the most unfavorable angle. During the iteration process, the step size is set to be in the range of 0.1 to 1.

[0119] Example 2

[0120] refer to Figure 2 The difference from Embodiment 1 is that the connection structure at each hoisting point of the steel cage includes four sets of hook devices for hooking on the outer ring steel bars of the steel cage and eight limiting strips 1 fixed on the outer ring steel bars of the steel cage. The limiting strips 1 are in pairs, and the hook devices are located between the corresponding pairs of limiting strips 1 to determine the position of each hoisting point.

[0121] refer to Figure 2The hook device includes a connecting block 2 with a groove at the bottom, two sets of arc-shaped hook plates 3 hinged to the bottom of the connecting block 2, and a drive mechanism 4 for driving the two sets of arc-shaped hook plates 3 to rotate simultaneously in opposite directions.

[0122] The connecting block 2 has an anti-detachment mechanism 5 for fixing the two sets of arc-shaped hook plates 3 in position; the two sides of the connecting block 2 are attached to the same pair of limit strips 1, the top of the connecting block 2 is connected to the bottom of the wire rope, and the two sets of arc-shaped hook plates 3 are set in opposite arc shapes; the bottom of the connecting block 2 has a vertically lifting plate 6 located between the two sets of arc-shaped hook plates 3, and the bottom of the lifting plate 6 is fixed with an arc-shaped pressure plate 61 for pressing the outer ring of the steel cage. The driving mechanism 4 drives the two arc-shaped hook plates 3 to rotate in opposite directions, and also drives the lifting plate 6 to descend.

[0123] The connecting block 2 is lowered between the same pair of limit strips 1 to quickly determine the lifting point position. The two sets of arc hook plates 3 are then aligned with the outer ring of the steel cage. The drive mechanism 4 is activated so that the two sets of arc hook plates 3 hook the outer ring of the steel cage. At the same time, the lifting plate 6 is lowered so that the arc pressure plate 61 presses against the outer ring of the steel cage. This makes the lifting point connection more stable after the steel cage is lifted, improving the accuracy of the calculation data and the safety of construction.

[0124] refer to Figure 2 and Figure 3 Each set of arc-shaped hook plates 3 contains two plates, which are arranged in an interlocking manner. Each arc-shaped hook plate 3 has a T-shaped groove 31 on its outer arc surface along its arc direction. A gravity block 32 slides on the outer arc surface of each arc-shaped hook plate 3. One side of the gravity block 32 extends into the T-shaped groove 31. The part of the gravity block 32 outside the T-shaped groove 31 is cylindrical, and both sides of the part of the gravity block 32 outside the T-shaped groove 31 extend out to the sides of the arc-shaped hook plate 3. An arc-shaped spring 33 is fixed between the inner wall of the T-shaped groove 31 near the bottom of the arc-shaped hook plate 3 and the gravity block 32. When the gravity block 32 is displaced by the arc-shaped hook plate 3, the arc-shaped spring 33 is stretched, which improves the rotational stability of the arc-shaped hook plate 3. When the arc-shaped hook plate 3 is reset during hoisting, the arc-shaped spring 33 pulls the gravity block 32 to reset, so as to facilitate the next hoisting.

[0125] refer to Figure 4 and Figure 5The drive mechanism 4 includes a drive motor 41 fixed to the outer wall of the connecting block 2, three first rotating shafts 42 horizontally rotatably connected within the connecting block 2 and parallel to each other, three sprockets 43 correspondingly and coaxially fixed on the first rotating shafts 42, a chain 44 sleeved and meshing on the three sprockets 43, a second rotating shaft 45 horizontally rotatably connected within the connecting block 2, a reversing gear 46 coaxially fixed on the second rotating shaft 45, and a linkage component 47 for driving the lifting plate 6 to rise and fall when the first rotating shafts 42 rotate; the three first rotating shafts 42 are arranged in a triangle, with one of the first rotating shafts... 42 is located above the other two first rotating shafts 42. The second rotating shaft 45 is parallel to the first rotating shaft 42 and located on one side of one of the lower first rotating shafts 42. The reversing gear 46 is also coaxially fixed on this first rotating shaft 42, and the two reversing gears 46 mesh with each other. The drive motor 41 is coaxially fixed to one of the lower first rotating shafts 42. The linkage component 47 is located between the upper first rotating shaft 42 and the lifting plate 6. One set of arc-shaped hook plates 3 is fixed on the second rotating shaft 45, and the other set of arc-shaped hook plates 3 is fixed on the lower first rotating shaft 42 away from the second rotating shaft 45.

[0126] refer to Figure 6 The linkage component 47 includes a linkage gear 471 coaxially fixed on the upper first rotating shaft 42 and a rack 472 vertically fixed on one side of the lifting plate 6. The linkage gear 471 is always meshed with the rack 472. After the connecting block 2 descends between the two limit bars 1, the drive motor 41 is started, causing the three first rotating shafts 42 to rotate synchronously and drive the second rotating shaft 45 to rotate in the opposite direction, so that the two sets of arc-shaped hook plates 3 rotate towards each other and hook the outer ring of the steel cage. At the same time, the upper first rotating shaft 42 drives the lifting plate 6 to descend through the linkage component 47, so that the arc-shaped pressure plate 61 presses against the outer ring of the steel cage, improving the operating efficiency and making the hook more stable.

[0127] refer to Figure 5 and Figure 6The anti-detachment mechanism 5 includes a ratchet 51 vertically fixed to one side of the lifting plate 6, a pawl 52 horizontally sliding within the connecting block 2 and engaging with the ratchet 51, and a separation component 53 for separating the pawl 52 from the ratchet 51. The helical teeth of the ratchet 51 are inclined upwards. The separation component 53 includes a sliding shaft 531 horizontally rotatably connected within the connecting block 2 and capable of sliding along its own axis, a limiting block 533 fixed to one end of the sliding shaft 531 extending out of the connecting block 2, and a return spring 532 fixed between the limiting block 533 and the outer wall of the connecting block 2. The end of the pawl 52 away from the ratchet 51 is fixed to the sliding shaft 531. After the lifting plate 6 has descended, the cooperation between the pawl 52 and the ratchet 51 can prevent the lifting plate 6 from rising. When it is necessary to release the hoisting, press the limit block 533 to make the sliding shaft 531 drive the pawl 52 to move laterally. After the pawl 52 and the ratchet 51 are separated, the drive motor 41 can be started to reset the arc hook plate 3 and the lifting plate 6, which improves the stability during hoisting and the convenience of operation when releasing the hoisting.

[0128] The implementation principle of Embodiment 2 of this application is as follows: the connecting block 2 is lowered between the same pair of limit strips 1 to quickly determine the lifting point position, and the two sets of arc-shaped hook plates 3 are made to face the outer ring of the steel cage. The drive motor 41 is started to make the three first rotating shafts 42 rotate synchronously and drive the second rotating shaft 45 to rotate in the opposite direction, so that the two sets of arc-shaped hook plates 3 rotate towards each other and hook the outer ring of the steel cage. At the same time, the upper first rotating shaft 42 drives the lifting plate 6 to descend through the linkage component 47, so that the arc-shaped pressure plate 61 is pressed against the outer ring of the steel cage, which can make the lifting point connection more stable after the steel cage is lifted, and improve the accuracy of the calculation data and the construction safety.

[0129] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for optimizing the design and stress calculation of hoisting points for ultra-long steel cages, characterized in that: Includes the following steps: Establish a general coordinate system for the hoisting points of the reinforcing cage, with one end of the reinforcing cage as the origin o, the horizontal direction as the x-axis, and the vertical direction as the y-axis. There are two steel wire ropes of lengths L1 and L2, each divided into two sections at the bottom, resulting in a total of four hoisting points. The steel wire rope of length L1 has a bifurcation point e and two hoisting points a and b; the steel wire rope of length L2 has a bifurcation point f and two hoisting points c and d. Based on the two steel wire ropes, establish two local coordinate systems for the hoisting points of the reinforcing cage, with a and c as the origins respectively, the horizontal direction as the x-axis, and the vertical direction as the y-axis. The length of the steel cage is l, the weight of the steel cage is G, and the tensions of the wire ropes ae, be, cf, and df are F1, F2, F3, and F4, respectively. During the hoisting process, points e and f are moving points, and the tensions of the same rope are equal. Fa and Fc are used to represent the tensions of ropes aeb and cfd, respectively, i.e., F1 = F2 = Fa, F3 = F4 = Fc. γ is the rotation angle of the steel cage, and θ1 and θ2 are the angles between ropes ae and cf and the x-axis, i.e., the angles between the ropes and the horizontal ground. During the reversal process, the lengths of ropes aeb and cfd remain constant. The trajectories of moving points e and f are ellipses with foci a and b, c and d as foci. Let the length of ae be Lae and the length of ab be Lab. Based on geometric relationships and the Law of Cosines: Let the length of cf be Lcf, and the length of cd be Lcd. Similarly, we can obtain: Let the length of the reinforcing cage between the origin o and the lifting point a be c1l, the length between lifting point a and b be c2l, the length between lifting point b and c be c3l, the length between lifting point c and d be c4l, and the remaining length of the reinforcing cage after lifting point d be c5l; the resultant force of the wire rope of length L1 be R1, and the resultant force of the wire rope of length L2 be R2. According to the moment balance, the equilibrium equation at point d is: R1[(c2+c3)lcosγ-L ae cosθ1+L cf cosθ2]=G[(c1+c2+c3-0.5)lcosγ+L cf cosθ2] The resultant force R2 of the rope is: R2 = G - R1 Based on the force conditions of the two wire ropes, we can conclude that: The reactions at suspension points a and b are: The reaction forces at suspension points c and d are: The distance from the location of minimum shear force in each span to the fixed point O of the reinforcing cage is: ab cross space: bc cross: cd span: The maximum bending moments in each span ab, bc, and cd are: in: c5 = 1 - c1 - c2 - c3 - c4 The bending moments at each lifting point a, b, c, and d are respectively 2. The method for optimizing the design and stress calculation of lifting points for ultra-long steel cages according to claim 1, characterized in that: When the reinforcing cage is only horizontally hoisted, without considering the change in the extreme value of the bending moment during the rotation stage, the optimal hoisting point is determined by the fact that the absolute values ​​of the maximum positive and negative bending moments of each major critical section of the pile are equal when it is in the horizontal position. The combined control equation is:

3. The method for optimizing the design and stress calculation of lifting points for ultra-long steel cages according to claim 1, characterized in that: The connection structure at each hoisting point of the steel cage includes a hook device for hooking the outer ring steel bars of the steel cage and several limiting strips (1) fixed on the outer ring steel bars of the steel cage. The hook device is located between two adjacent limiting strips (1) to determine the position of the hoisting point. The hook device includes a connecting block (2), an arc-shaped hook plate (3), a driving mechanism (4), and an anti-detachment mechanism (5). The top of the connecting block (2) is connected to the bottom end of the wire rope. There are two arc-shaped hook plates (3) and they are arranged opposite each other. Both arc-shaped hook plates (3) are hinged to the bottom of the connecting block (2). The driving mechanism (4) is installed on the connecting block (2) and is used to drive the two arc-shaped hook plates (3) to rotate in opposite directions to hook the outer ring steel bars of the steel cage. The anti-detachment mechanism (5) is installed on the connecting block (2) and is used to fix the two arc-shaped hook plates (3) after hooking the outer ring steel bars of the steel cage.

4. The method for optimizing the design and stress calculation of lifting points for ultra-long steel cages according to claim 3, characterized in that: The bottom of the connecting block (2) has a lifting plate (6) that moves up and down. The lifting plate (6) is located in the middle of the two arc-shaped hook plates (3). The bottom of the lifting plate (6) is fixed with an arc-shaped pressure plate (61) for pressing the outer ring of the steel cage. The driving mechanism (4) drives the arc-shaped hook plates (3) to rotate in opposite directions while also driving the lifting plate (6) to descend.

5. The method for optimizing the design and stress calculation of lifting points for ultra-long steel cages according to claim 4, characterized in that: The drive mechanism (4) includes a drive motor (41), a first rotating shaft (42), a sprocket (43), a chain (44), a second rotating shaft (45), a reversing gear (46), and a linkage assembly (47). There are three first rotating shafts (42), all of which are horizontally rotatably connected to the connecting block (2). Two of the first rotating shafts (42) are located near the two ends of the connecting block (2), and the other first rotating shaft (42) is located above the two first rotating shafts (42). The drive motor (41) is fixed to one side of the connecting block (2) and coaxially fixed to one of the first rotating shafts (42). There are three sprockets (43), each coaxially fixed to the corresponding first rotating shaft (42). The chain (44) meshes with the first rotating shaft (42). The first rotating shaft (42) is connected to three sprockets (43); the second rotating shaft (45) is horizontally rotatably connected to the connecting block (2) and located on one side of the first rotating shaft (42) below it. There are two reversing gears (46), which are coaxially fixed on the first rotating shaft (42) and the second rotating shaft (45) respectively, and the two reversing gears (46) mesh with each other; one arc-shaped hook plate (3) is fixed on the second rotating shaft (45), and the other arc-shaped hook plate (3) is fixed on the first rotating shaft (42) below it, away from the second rotating shaft (45); the linkage component (47) is set between the upper first rotating shaft (42) and the lifting plate (6), and is used to drive the lifting plate (6) to rise and fall when the first rotating shaft (42) rotates.

6. The method for optimizing the design and stress calculation of lifting points for ultra-long steel cages according to claim 5, characterized in that: The linkage component (47) includes a linkage gear (471) and a rack (472). The linkage gear (471) is coaxially fixed with the upper first rotating shaft (42), and the rack (472) is fixed on one side of the lifting plate (6). The linkage gear (471) and the rack (472) are always meshed.

7. The method for optimizing the design and stress calculation of lifting points for ultra-long steel cages according to claim 5, characterized in that: The anti-detachment mechanism (5) includes a ratchet (51), a pawl (52), and a separation component (53). The ratchet (51) is fixed to one side of the lifting plate (6), and the helical teeth of the pawl (52) are inclined upward. The pawl (52) is rotatably connected in the connecting block (2) and engages with the ratchet (51). The separation component (53) is used to separate the pawl (52) from the ratchet (51).

8. The method for optimizing the design and stress calculation of lifting points for ultra-long steel cages according to claim 7, characterized in that: The separation assembly (53) includes a sliding shaft (531), a return spring (532), and a limiting block (533). The axis of the sliding shaft (531) is parallel to the length direction of the helical teeth of the ratchet (51). The sliding shaft (531) is rotatably connected to the connecting block (2), and the sliding shaft (531) can slide along its own axis. The end of the pawl (52) away from the ratchet (51) is fixed on the sliding shaft (531). One end of the sliding shaft (531) extends out of the side wall of the connecting block (2) and is fixed to the limiting block (533). The return spring (532) is fixed between the limiting block (533) and the side wall of the connecting block (2).

9. The method for optimizing the design and stress calculation of lifting points for ultra-long steel cages according to claim 3, characterized in that: Each of the arc-shaped hook plates (3) has a gravity block (32) sliding along its own curvature direction on its outer arc surface, and both sides of the gravity block (32) protrude from the side wall of the arc-shaped hook plate (3).

10. The method for optimizing the design and stress calculation of lifting points for ultra-long steel cages according to claim 9, characterized in that: The outer arc surface of the arc hook plate (3) is provided with a T-shaped groove (31) along its own arc direction. One end of the gravity block (32) is located in the T-shaped groove (31), and an arc spring (33) is fixed between the inner wall of the T-shaped groove (31) near the bottom of the arc hook plate (3) and the gravity block (32).

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