Large cross-section plane truss cumulative slip anti-swing device and method of use thereof

Abstract

This invention discloses a cumulative sliding anti-sway device for large-section planar trusses and its application method, belonging to the field of steel structure construction technology. The device involves setting temporary supports on both sides of the sliding path, anchoring flexible cables at the top, and installing self-adjusting pulleys on the upper chord of the planar truss to be slid. The cable wraps around the pulley at least once, forming a purely flexible closed loop. During the sliding process, the pulley rotates in real time with the truss displacement, automatically adjusting the length difference between the two sides of the cable, applying an instantaneous lateral force opposite to the sway direction to the upper chord, thereby controlling the mid-span amplitude within a safe range. This invention also provides quantitative formulas for cable resistance, preload, support stiffness, and dismantling frequency, ensuring a data-driven process throughout the "design-construction-monitoring-dismantling" process. The device is entirely hardware-based, allowing for quick assembly and disassembly, and reuse. It eliminates the need for extended intermediate supports or rigid diagonal braces, significantly simplifying the process and reducing construction risks. It is suitable for cumulative sliding construction of planar trusses with spans of 60 m and above, and a height-to-span ratio of 1 / 5 to 1 / 12.

Description

Technical Field

[0001] This invention relates to the field of steel structure construction technology in building engineering, and in particular to an anti-sway device and its usage method for suppressing large-amplitude swaying of a large-section planar truss during the initial stage of sliding installation using the cumulative sliding method. Background Technology

[0002] With the rapid development of large-span spatial structures, large-section planar trusses are widely used in various roof systems due to their advantages such as low steel consumption, light weight, and high load-bearing efficiency. Due to site constraints, traditional segmented hoisting or overall lifting schemes are often difficult to implement, making cumulative sliding technology the preferred choice: after assembling the truss on the outside of the building, hydraulic crawlers are used to push it segment by segment along a pre-set track to the design position.

[0003] However, in the initial stage of slippage, typically only 2-3 trusses form a local frame, resulting in low out-of-plane stiffness and a cantilevered upper chord. The 20-30 cm start-stop impact of the hydraulic crawler per stroke causes significant swaying at mid-span of the truss, with the swaying becoming more severe as the span and truss cross-section increase. Currently, quantitative calculation methods are lacking in engineering practice, and qualitative control is often achieved by extending intermediate supports or using temporary rigid bracing, but this approach has the following shortcomings: 1) The support needs to extend to the lower anchoring layer, which requires a large amount of material and has a long erection period; 2) The rigid support and the sliding are not synchronized, which can easily introduce additional secondary stress; 3) The disassembly and assembly are complex, affecting the efficiency of subsequent truss assembly and sliding; 4) Unable to adapt to the instantaneous inertial impact caused by the crawler's step-by-step start and stop.

[0004] Therefore, there is an urgent need for a flexible anti-sway device that is simple in structure, quick to assemble and disassemble, and can automatically adjust as the sliding process progresses, in order to solve the safety and deformation hazards caused by excessive swaying in the early stage of cumulative sliding of large cross-section planar trusses. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies where large-section planar trusses experience excessive mid-span swaying during the initial stage of cumulative sliding due to insufficient out-of-plane stiffness and inertial impact from start-stop. It provides a simple, quick-assembly and disassembly flexible anti-sway device and its usage method that automatically adjusts tension as the sliding progresses. The aim is to control the sway amplitude within a safe range without lengthening intermediate supports or installing rigid diagonal braces, thus ensuring the safety and efficiency of sliding construction.

[0006] To achieve the above objectives, the present invention is implemented as follows: A large-section planar truss cumulative slip anti-sway device includes: Temporary supports (3) are set up on both sides of the sliding path; Flexible cable (12) anchored at both ends to the top of temporary support (3); The self-adjusting pulley (13) installed on the upper chord of the plane truss (2) to be slidable can change its rotation angle in real time with the displacement of the truss, so that the length difference between the two sides of the cable (12) automatically matches the sliding stroke, thereby applying an instantaneous lateral force to the truss in the opposite direction of the swing, and realizing the swing suppression.

[0007] This invention introduces the concept of "flexible follow-up" into cumulative sliding construction, which can provide continuous damping during the 20-30 cm step jacking process with simple hardware, overcoming the drawbacks of traditional rigid supports that are not synchronized and have large additional secondary stress.

[0008] To further enhance safety, adaptability, and maintainability, the present invention makes the following improvements to the basic solution, resulting in corresponding technical effects: (1) Furthermore, the design value of the cable resistance T satisfies T ≥ k·(m·a max ) / n, k∈[2,5].

[0009] This formulaic constraint ensures that the cable still has sufficient safety reserve under maximum start-stop inertia, avoiding the risk of cable breakage caused by "insufficient strong constraints".

[0010] (2) Further, the self-adjusting pulley rotation resistance torque Mr≤0.1·F·R, so that the cable length adjustment lag time Δt≤10% of the single stroke.

[0011] Effect: Ensures that the "instantaneous follow-up" is synchronized with the crawler's movements, preventing "hard pulling" or "loosening" phenomena caused by pulley jamming.

[0012] (3) Further, the initial preload T0 = α·EI / L 2 , α∈[0.3,1.2].

[0013] Effect: The preload range is quantitatively given by the out-of-plane stiffness EI of the truss itself, which provides effective constraints and avoids the additional bending moment of the truss caused by excessive preload.

[0014] (4) Further, the pulley arrangement position x∈[0.25L,0.5L].

[0015] Effect: It increases the sway suppression efficiency η≥60%, forms the maximum reverse bending moment near the mid-span, and significantly reduces the amplitude.

[0016] (5) Furthermore, the horizontal stiffness at the top of the temporary support is Ks ≥ β·(EA / L) c ), β∈[0.8,2.0].

[0017] Effect: Incorporating "support deformation" into the system stiffness calculation prevents excessive displacement of anchor points from weakening the cable restraint effectiveness.

[0018] (6) Further, a force measuring element (14) is added to monitor T in real time, and an alarm is triggered if the deviation exceeds the limit.

[0019] Effect: It forms a closed-loop management system, which can detect abnormalities such as rope slack and wheel jamming in a timely manner during the sliding process, thereby improving construction safety.

[0020] (7) Further, a spiral buckle (15) is provided in the middle section of the cable, and the adjustment stroke S≥0.02L.

[0021] Effect: Quickly compensates for elongation caused by temperature and creep, eliminating the need to disassemble and reassemble anchorages, thus improving construction efficiency.

[0022] (8) Furthermore, the height h of the double-sided guards of the pulley is ≥1.2d to prevent it from slipping out of the groove when the extreme swing angle θ is ≥15°.

[0023] Effect: Enhances reliability under extreme working conditions and prevents "jump rope" failure.

[0024] Furthermore, the present invention also proposes a method of use based on the above description (corresponding to claim 10). This invention also proposes an output control process based on the above-mentioned large-section planar truss cumulative slip anti-sway device: S1 Calculates T and T0 according to the formula and sets the preload; S2 is installed with anchor points and pulleys to form a flexible closed loop; S3 sliding start, pulley self-adjustment in real time, system dynamically meets resistance, position and stiffness requirements; S4 When the out-of-plane natural frequency f ≥ γ·√(g / δ) (γ∈[1.2,2.0]), the device is removed and the device enters self-balancing slip.

[0025] This method uses a "frequency threshold" as a removal criterion to achieve "quantitative installation and quantitative removal" of the device, avoiding the safety risks caused by experience-based early or late removal.

[0026] In general, this invention replaces the rigid diagonal brace with a "flexible follow-up" and adds only a set of lightweight cable-pulley closed loops on both sides of the sliding path. This transforms the original extended support that needed to extend downward and be rigidly connected to the main structure into a pure tension component that can be deployed at the top of the temporary ground support (3). Since the pulley (13) can adjust the rope length in real time, the system has an instantaneous response capability to the inertial impact generated by the 20-30 cm step start and stop of the hydraulic crawler. It can provide a reverse lateral force before the swing is amplified, so that the swing trend in the middle of the span is continuously "absorbed" rather than "hardened", which greatly reduces the bending moment outside the structure and the fatigue risk of the connection nodes.

[0027] Furthermore, the entire device is made entirely of metal, and installation and dismantling do not require large machinery or high-altitude welding; only ground wrenches are needed for repeated operation. With the help of quantitative formulas for tension, stiffness, frequency, etc., the construction party can complete the pre-design of "one table to calculate everything" before sliding, compare it in real time through force measuring components (14) during sliding, and dismantle it in one go according to the natural frequency threshold after sliding, realizing a rapid operation mode of "install, use, and remove immediately". In summary, this invention significantly simplifies the process flow, reduces reliance on site and large hoisting resources, and provides a simpler, lighter, and more controllable anti-sway solution for the cumulative slippage of space-constrained, large-span, high-section planar trusses. Attached Figure Description

[0028] Figure 1 Schematic diagram of the overall arrangement of the cumulative sliding of the large cross-section truss.

[0029] Figure 2 Schematic diagram of the anti-sway device arrangement for a planar truss (3D).

[0030] Figure 3 Schematic diagram of the cross-sectional layout (sliding direction) of the anti-sway device for the planar truss.

[0031] Figure 4 Diagram of the top pulley structure of the anti-sway device.

[0032] Figure 5 Detailed diagram of the anti-sway pulley (13) during use.

[0033] Figure 6 Schematic diagram of nonlinear tensioning of cable (12).

[0034] Figure 7(a) is a schematic diagram of the installation phase.

[0035] Figure 7(b) is a schematic diagram of the slip phase.

[0036] Figure 7(c) is a schematic diagram of the demolition stage.

[0037] Figure 8 Working principle diagram of hydraulic crawler.

[0038] Figure 9 A schematic diagram of a large-section planar truss swinging during sliding. Detailed Implementation

[0039] The following is in conjunction with the appendix Figures 1-9 This document provides a detailed description of the specific implementation of the present invention, "A Large-Section Planar Truss Cumulative Slip Anti-Sway Device and Its Usage Method." The embodiments are for illustrative purposes only and do not limit the scope of protection.

[0040] I. Project Overview This example illustrates a roofing project for an exhibition hall. The sliding span is L = 72 m, the truss height-to-span ratio is 1 / 8, and the mass of a single truss is m = 48 t. Two hydraulic crawlers are used for synchronous jacking, with a single stroke of 300 mm. Since vehicles cannot enter the building's interior, a cumulative sliding process is employed: after completing two trial assemblies on the outer assembly platform, the trusses are gradually jacked to their designed positions along sliding tracks fixed to the concrete floor.

[0041] II. Equipment Layout (e.g.) Figures 1-3 ) A temporary support (3) is set on each side of the sliding starting point, sharing the cup-shaped foundation with the existing sliding support (4). The top elevation of the support is consistent with the top surface of the sliding track.

[0042] Each temporary support (3) has a Q355B fixed lug plate (11) welded to its top. The plate is 16 mm thick and has double stiffening ribs. The out-of-plane stiffness meets the requirement of Ks≥1.5·(EA / L) c (β is taken as 1.5 in the formula).

[0043] Φ20 mm steel wire rope is selected as the cable (12), with a breaking strength ≥270 kN, according to T≥k·(m·a) max ) / n calculation: k is 3, a max Take 0.15 m / s 2 Since n = 2, T ≥ 54 kN, with a safety factor of 5, which meets the requirements.

[0044] A self-adjusting pulley (13) is installed at a distance of 0.38L (approximately 27 m) from the left end of the upper chord of the first truss. This position is within the optimal range of 0.25L to 0.5L. The pulley rope groove depth is 30 mm (1.5d), and the height of the double-sided retaining edge is 24 mm (1.2d) to prevent derailment due to extreme swing angles θ≥15°.

[0045] III. Pulley construction and rope length self-adjustment (e.g.) Figure 4 , Figure 5 ) The pulley (13) consists of a fixed lug (131), a movable pulley (132), and a fixed shaft (133). The measured rotational resistance torque Mr of the movable pulley is ≤0.8 N·m, which satisfies Mr≤0.1·F·R (F is 54 kN, R is 0.05 m, and the upper limit is 270 N·m), ensuring that Δt≤0.3 s, which is less than 10% of the single-stroke time of 3 s. The cable wraps around the pulley 1.5 times. During the sliding process, when one side of the rope lengthens, the other side automatically shortens, forming nonlinear tension (such as...). Figure 6 ).

[0046] IV. Application and monitoring of preload (e.g.) Figure 6 , Figure 7a ) Connect the two sections of wire rope with a spiral buckle (15), and adjust the stroke S = 1.8 m ≥ 0.02L (1.44 m). According to T0 = α·EI / L 2 Calculate: EI = 5.2 × 10 11 N·mm 2 α is set to 0.6, resulting in T0 = 18 kN. Tighten the screw thread to the set value using a force wrench and lock it. Connect the force measuring element (14) in series at the end of the rope, with a range of 0-100 kN. When the displayed value is <9 kN or >27 kN, an on-site audible and visual alarm will be triggered, prompting the user to re-tension or check the pulley for jamming.

[0047] V. Sliding process (e.g.) Figure 7b , Figure 8 ) The crawler operates in a four-step cycle: "extension cylinder - clamping - retraction cylinder - release clamping," with each step covering 300 mm. The maximum acceleration at startup is 0.15 m / s². 2 The inertial force causes the upper chord of the truss to swing outward by about 60 mm. At this time, the instantaneous tension on one side of the cable rises to 45 kN, generating a reverse horizontal force of about 22 kN on the truss. The swing is suppressed to <15 mm within 1.2 s, which meets the on-site safety requirement that "the amplitude does not exceed 1 / 1000 of the span". The sliding continues, and the movable pulley (13) rotates accordingly. The difference in rope length on both sides matches the sliding stroke in real time, without the need for manual intervention.

[0048] VI. Demolition Criteria and Implementation Figure 7c ) After the fourth truss is installed, the out-of-plane natural frequency f of the structure increases from 1.0 Hz to 1.6 Hz. Based on f ≥ γ·√(g / δ), γ is taken as 1.5, and g = 9.81 m / s². 2 δ=72 mm, the threshold is 1.48 Hz, the current 1.6 Hz>1.48 Hz, which meets the dismantling conditions. The spiral buckle is released, the wire rope is retrieved, and the pulley (13) is removed. The whole process takes 15 minutes. After the device is removed, it slides into the self-balancing stage. The subsequent frames continue to be assembled and pushed, without any additional swaying abnormalities.

[0049] VII. Extreme operating condition verification (e.g.) Figure 9 ) To verify reliability, an extreme working condition of sudden depressurization of a single crawler was simulated on site: the acceleration direction reversed at the moment of depressurization, the truss swayed in the opposite direction with a peak velocity of 0.22 m / s, and the maximum tension of the cable was measured to be 68 kN, which was still 25% lower than the breaking tensile force of 270 kN. The device was intact and the structure was undamaged, proving that the flexible restraint still has sufficient safety margin under extreme inertial impact.

[0050] VIII. Summary This embodiment uses only two sets of temporary supports, two steel wire ropes, and two pulleys to complete the initial swing control of the 72 m span large cross-section truss during sliding. The entire process is quantitatively designed, monitored in real time, and dismantled as needed, fully demonstrating the technical characteristics of "extremely simple structure, immediate response, rapid installation and dismantling, and reusability".

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A device for preventing swaying due to cumulative slippage of a large-section planar truss, characterized in that, include: Temporary supports (3) are set up on both sides of the sliding path; Flexible cables (12) anchored at both ends to the temporary support (3); and A self-adjusting pulley (13) is installed on the upper chord of the plane truss (2) to be slid. The pulley (13) is configured to change its own rotation angle in real time with the displacement of the truss during the cumulative sliding process, so that the length difference between the two sides of the cable (12) automatically matches the sliding stroke, thereby applying an instantaneous lateral force opposite to the swing direction to the plane truss (2) to suppress the large swing in the early stage of sliding.

2. The large-section planar truss cumulative slippage anti-sway device according to claim 1, characterized in that, The resistance design value T of the cable (12) satisfies T ≥ k·(m·a max ) / n Where m is the mass of a single truss, a max is the maximum acceleration for starting and stopping the hydraulic crawler, n is the effective number of cable constraints, k is the safety factor, and k∈[2,5].

3. The large-section planar truss cumulative slippage anti-sway device according to claim 1 or 2, characterized in that, The rotational resistance torque Mr of the self-adjusting pulley (13) satisfies Mr ≤ 0.1·F·R Where F is the cable tension and R is the pulley radius, to ensure that the cable length adjustment lag time Δt does not exceed 10% of the crawler's single-stroke time.

4. The large-section planar truss cumulative slippage anti-sway device according to any one of claims 1-3, characterized in that, The initial preload T0 of the cable (12) is determined by... T0 = ​​α·EI / L 2 Determine that EI is the lateral bending stiffness of the upper chord of the truss, L is the sliding span, and α is the preload coefficient, α∈[0.3,1.2].

5. The anti-sway device for cumulative slippage of large-section planar trusses according to any one of claims 1-4, characterized in that, The arrangement position x of the pulley (13) in the truss span direction satisfies 0.25L ≤ x ≤ 0.5L To maximize the oscillation suppression efficiency η, where η ≥ 60%.

6. The anti-sway device for cumulative slippage of large-section planar trusses according to any one of claims 1-5, characterized in that, The top horizontal stiffness K of the temporary support (3) s satisfy K s ≥ β·(EA / L c ) Where EA is the axial stiffness of the cable, and L c Let be the length of the free segment of the cable, and β be the stiffness ratio, β∈[0.8,2.0].

7. The large-section planar truss cumulative slippage anti-sway device according to any one of claims 1-6, characterized in that, It also includes a force measuring device (14) for real-time monitoring of cable tension T, which issues an alarm signal when T>1.5T or T<0.5T to prompt readjustment of preload or check for pulley jamming.

8. The anti-sway device for cumulative slippage of large-section planar trusses according to any one of claims 1-7, characterized in that, The cable (12) is composed of two sections connected by a spiral buckle (15). The adjustment stroke S of the spiral buckle (15) is not less than 0.02L, which is used to quickly compensate for creep or thermal elongation during the sliding process.

9. The anti-sway device for cumulative slippage of large-section planar trusses according to any one of claims 1-8, characterized in that, The self-adjusting pulley (13) has double-sided guards on its outer periphery, with a guard height h≥1.2d, where d is the diameter of the cable, to prevent the cable from slipping out of the groove when the extreme swing angle θ≥15°.

10. A method of using the large-section planar truss cumulative slip anti-sway device as described in any one of claims 1-9, characterized in that, include: S1 calculates and sets the cable resistance design value T and the initial preload T0 according to claims 2 and 4; S2 Anchor points and self-adjusting pulleys (13) are installed on the temporary support (3) and the upper chord of the truss respectively to form a flexible closed loop; S3 initiates sliding, and pulley (13) self-adjusts in real time, so that the system dynamically meets the rotational resistance of claim 3 and the positional requirements of claim 5; S4 When the out-of-plane natural frequency f of the truss obtained by monitoring or calculation satisfies f≥γ·√(g / δ), release the cable (12) and the device stops working; where γ∈[1.2,2.0], g is the gravitational acceleration, and δ is the allowable swing amplitude.

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