Deflection-controllable non-grounded formwork frame using cable-supported control and its design method

Abstract

This invention discloses a non-grounded formwork support with controllable deflection using tensioned wire and its design method, comprising a support frame, a jacking device, steel strand units, and an anchoring device. The support frame is fixed to the top of a pier column via corbels, with the middle section of the support frame located above the pier column, and both ends extending outwards beyond the pier column area. The jacking device includes two jacks, the bottoms of which are fixedly supported in the middle section of the support frame. The steel strand units are made of steel strands, with the middle section of the steel strands arranged on the top support components of the two jacks, and both ends of the steel strands extending outwards to both ends of the support frame and penetrating downwards through the support frame. The anchoring device anchors and locks the steel strands through the ends of the support frame. The advantages of this invention are: compared with traditional steel supports, by using the steel strand units and I-beam supports to share the load, the support frame stiffness is increased by 20%-30%, and the deflection control accuracy reaches ±0.01mm, making it suitable for the construction environment of large-span, high-load cantilever cap beams.

Description

Technical Field

[0001] This invention belongs to the field of bridge engineering construction technology, specifically relating to a non-grounded formwork support with controllable deflection using tensioned wire and its design method. Background Technology

[0002] During the construction of cantilever cap beams in bridge engineering, the cap beam formwork system needs to withstand the wet weight of the cap beam concrete during pouring, the impact caused by concrete pouring, and multiple loads caused by construction machinery and personnel. Due to the stress characteristics of the cantilever structure, the formwork needs to meet the requirements of high strength and low deflection. The erection of traditional formwork systems has certain requirements on the bearing capacity of the foundation. The construction and transfer of high piers are inconvenient, and it is easy to cause overall settlement, uneven settlement, large elastic deformation, and uncontrollable non-elastic deformation. The large deformation before and after concrete pouring during the construction stage is difficult to adjust, which can easily lead to quality hazards such as linear deviation of the cap beam and local cracks, affecting the safety and durability of the structure.

[0003] Currently, the most common scaffolding scheme for cantilever cap beam construction is the ground-based scaffolding, which uses steel pipe supports and structural steel to bear the load of the cap beam during casting. However, this traditional method has many shortcomings: (1) Traditional ground-supported scaffolding is costly, labor-intensive, and requires a certain foundation bearing capacity. It is also inconvenient for construction to be carried out in a continuous flow. It is costly and cumbersome to construct.

[0004] (2) Traditional ground support may experience local settlement and uneven settlement before and after concrete pouring due to its large self-weight. Due to its large body height, elastic deformation is difficult to control. Due to the large number of connection nodes, uncontrollable inelastic deformation may also occur, making the overall construction control difficult.

[0005] (3) Traditional support monitoring methods are mostly manual periodic inspections, that is, deflection and pressure data are manually collected by tools such as level and tension gauge. The sampling frequency is low, the data lag is strong, and it is impossible to capture the dynamic deformation of the support in real time. When the limit is exceeded, it is difficult to adjust in time and the best adjustment time is easily missed.

[0006] Traditional support systems not only fail to meet the high-precision construction requirements of cantilever girder construction, but also suffer from high safety risks, high costs, and low construction efficiency. Therefore, there is an urgent need for a girder support design method and control system that can simultaneously meet the requirements of good stiffness enhancement, efficient tension force transfer, stable and controllable construction, and reasonable cost under different cantilever lengths and load conditions. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of the prior art by providing a non-grounded formwork support with controllable deflection using tensioned wire and its design method. This non-grounded formwork support uses steel strand units and I-beam supports to work together to share the load, thereby improving the rigidity of the support and the accuracy of deflection control.

[0008] The objective of this invention is achieved through the following technical solutions: A deflection-controllable, tension-controlled, non-grounded formwork support includes a support frame, a jacking device, steel strand units, and an anchoring device; wherein: The support frame is installed on top of the pier column. The support frame includes two transverse load-bearing steel beams and several longitudinal connecting rods. Corbels are installed at both ends of the longitudinal direction of the pier column, and the two load-bearing steel beams are supported and fixed by the corbels at both ends of the longitudinal direction. The connecting rods are installed between the two load-bearing steel beams to connect and form the support frame as a whole. The middle area of ​​the load-bearing steel beam is located above the pier column, and the two ends of the load-bearing steel beam extend outward from the area of ​​the pier column. The load-bearing steel beam is equipped with the jack device, the steel strand unit, and the anchoring device; the jack device includes two jacks, the bottoms of which are fixedly supported in the middle area of ​​the load-bearing steel beam; the top of the jacks is provided with a top support component, which adopts an arc-shaped groove structure. The steel strand unit is made of steel strands, the middle of which is arranged on the top support assembly of the two jacks, and the two ends of the steel strands extend outward to the two ends of the load-bearing steel beam and pass downward through the load-bearing steel beam. The anchoring device anchors and locks the steel strand through the end of the load-bearing steel beam.

[0009] An anti-slip rubber pad is attached to the arc-shaped groove structure of the top support component, and the friction coefficient of the anti-slip rubber pad is ≥0.6.

[0010] The anchoring device includes an anchor, a wedge, a thickened anchor plate, and an anti-loosening element. The thickened anchor plate is fitted onto the lower surface of the load-bearing steel beam, and a through hole is provided in the center of the thickened anchor plate for the steel strand to pass through. The anchor is a cylindrical or square steel anchor ring, with its front end face abutting against the outer end face of the thickened anchor plate. A tapered hole is provided in the center of the anchor, the taper of which matches the outer tapered surface of the wedge to wedge the wedge and transmit tension. The rear end of the anchor is provided with an external thread to connect to the anti-loosening element. The wedge is composed of two or three wedge-shaped alloy steel plates forming a ring, and the inner hole of the wedge is provided with reverse teeth or trapezoidal threads to directly engage the steel strand. The anti-loosening element is provided at the rear end of the anchor to press against the wedge.

[0011] The non-grounded formwork support also includes a closed-loop monitoring system, which comprises non-contact displacement gauges, string pressure sensors, strain sensors, a data acquisition instrument, and a terminal platform. Two sets of non-contact displacement gauges are arranged on the lower surfaces of both ends of the load-bearing steel beam. The string pressure sensors are connected in series in the hydraulic circuit of the jack. The strain sensors are located on the upper surface of the middle section of the load-bearing steel beam. The data acquisition instrument is connected to collect monitoring data from the non-contact displacement gauges, string pressure sensors, and strain sensors, and is communicatively connected to the terminal platform.

[0012] A design method for a non-grounded formwork support with controllable deflection using tensioned wire, involving any of the aforementioned methods, includes the following steps: S1: Calculate the length of the load-bearing steel beam in the support structure. L 2 and the length of the cantilever section of the load-bearing steel beam. L 0 The calculation formula is as follows: L 2 = L 1 +2 0.5= L 1 +1 ; in: L 1 The length of the cap beam to be poured for the aforementioned non-grounded formwork support; L 3 The center-to-center distance between adjacent corbels on the pier; S2: Calculate the height of the point where the tension force of the steel strand is applied. H 1 The calculation formula is as follows: ; in: θ The tension angle of the steel strand; L 4 The tension force applied to the steel strand is limited to the distance from the center of the load-bearing steel beam to the node, within the range between the corbel anchor point and the pier column, i.e. ( L 3 / 2) ≤ L 4 ≤( b0 / 2) ; b 0 The width of the pier column; S3: Calculate the self-weight load of the cap beam. G 3 The calculation formula is as follows: ; in: ρ c This refers to the density of concrete. h 1 The height of the cap beam; b 1 The width of the cap beam; S4: Calculate the self-weight load of the formwork for the cap beam. G 3 The calculation formula is as follows: ; in: q m The weight per unit area of ​​the template; S5: Calculate the self-weight load of the support. G 1 The calculation formula is as follows: ; in: ρ s The density of the steel in the load-bearing steel beam of the bracket; A 0 The cross-sectional area of ​​the load-bearing steel beam; S6: Calculate the loads on construction workers and equipment. F 1 The calculation formula is: ; in: q h This refers to the standard value of construction live load; S7: Calculate load combination values F s The calculation formula is as follows: ; S8: Calculate the strength of the support, using the following formula: ; in: S 1 The maximum stress is the load-bearing steel beam of the support frame; W 1 The interfacial modulus of the I-beam used for the load-bearing steel beam is determined by consulting the I-beam model. [ f The design strength of the steel used in the load-bearing steel beam is [not specified]. M 1 The maximum bending moment of the support is calculated using the following formula: M 1 =F s L 0 1.1 ; S9: Calculate the stiffness of the support, using the following formula: ; in: D The deflection at the end of the cantilever section of the load-bearing steel beam; E The elastic modulus of the steel in the load-bearing steel beam is given. I The moment of inertia of the load-bearing steel beam section is determined by consulting the I-beam model. S10: Calculate the force required to be applied by the jack. F D The calculation formula is: ; ; in: F T1 This is the vertical component of the tension force of the steel strand; [D] represents the deflection control target value at the end of the cantilever section of the load-bearing steel beam; S11: The tension force required to tension the steel strand, as calculated. F T2 and the maximum design thrust of the jack F D-MAX The stability of the jack device is calculated using the following method: ; in: S DThe maximum stress of the jack device; [ f D The design strength of the steel used in the connection between the jack device and the load-bearing steel beam is specified. ; .

[0013] The advantages of this invention are: (1) Compared with traditional steel supports, the stiffness of the supports is increased by 20%-30% (up to 5×10) through the coordinated force sharing between the steel strand units and the I-beam supports. 5 With a deflection control accuracy of ±0.01mm (above kN / m), it can adapt to the construction environment of cantilever cap beams with large spans and high loads. (2) Compared with the traditional support construction process, the design method is carried out in accordance with the standardized process of "target setting-deployment-building-tensioning-verification", and the core components (jack device, steel strand, anchoring device) adopt modular design, which shortens the assembly time by 20% and can effectively improve construction efficiency. (3) Compared with traditional supports, the use of tension strengthening technology replaces part of the steel, thereby reducing the amount of steel used and lowering costs; (4) Compared with traditional support systems, this device can be reused repeatedly and has better energy-saving and environmental protection performance; (5) Compared with the traditional "manual monitoring" of the support, the closed-loop monitoring system realizes real-time acquisition of multi-dimensional data (deflection, pressure, tilt angle), and the response time of exceeding the limit is ≤1s. It automatically outputs control suggestions, avoids construction risks caused by human misjudgment, and improves construction safety by more than 50%. (6) Compared with the traditional "heavy steel stacking" support, the tension strengthening technology replaces some heavy steel, and the core components are designed to be lightweight (such as jacks weighing ≤50kg / unit), which can reduce the overall load of the support during high-altitude construction and is suitable for lightweight construction platforms such as climbing formwork and hanging baskets. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the non-grounded formwork support frame in this invention; Figure 2 This is a schematic diagram of the arrangement of the closed-loop monitoring system on the non-grounded formwork frame in this invention; Figure 3 This is a schematic diagram showing the dimensions of the non-ground-supported formwork frame in this invention; Figure 4 This is a schematic diagram of the stress distribution of the non-grounded formwork support system in this invention; Figure 5 This is a schematic diagram illustrating the construction process of the tensioned string system in this invention; Figure 6The present invention corresponds to Figure 5 A schematic diagram of the construction process of a tensioned cable system from a top-down perspective; The reference numerals for each of the attached drawings are as follows: 1. Steel strand unit; 2. Support; 3. Jack; 4. Top support assembly; 5. Anchorage device; 6. Cap beam; 7. Pier column; 8. Corbel; 9. Non-contact displacement gauge; 10. String pressure sensor; 11. Strain sensor; 12. Data acquisition instrument; 13. Terminal platform. Detailed Implementation

[0015] The features and other related features of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate understanding by those skilled in the art: Example: Figure 1-6 As shown, this embodiment specifically relates to a non-grounded formwork support frame with controllable deflection using tension control, including a support 2, a jack device, a steel strand unit 1, an anchoring device 5, and a closed-loop monitoring system.

[0016] like Figure 1-6 As shown, the support 2 is set on the top of the pier 7. The support 2 includes two load-bearing steel beams arranged in the transverse direction and several connecting rods arranged in the longitudinal direction. Corbels 8 are respectively set at both ends of the longitudinal direction of the pier 7. The two load-bearing steel beams are supported and fixed by the corbels 8 at both ends of the longitudinal direction. Specifically, two corbels 8 are set at each end. The connecting rods are set between the two load-bearing steel beams to connect and form a whole support 2. The middle area of ​​the load-bearing steel beam is located above the pier 7, and the two ends of the load-bearing steel beam extend outward from the area of ​​the pier 7.

[0017] like Figure 1-6 As shown, a jack device, a steel strand unit 1, and an anchoring device 5 are installed on the load-bearing steel beam. The core function of the jack device is to apply and dynamically adjust the tension force to the steel strand. It includes two jacks 3 (rated tonnage ≥ 500kN, even number symmetrically arranged). The bottoms of the two jacks 3 are fixedly supported in the middle area of ​​the load-bearing steel beam by jack brackets. A top support component 4 is installed on the top of the jacks 3. The top support component 4 adopts an arc-shaped groove structure (the radius of curvature matches the diameter of the steel strand, with a deviation ≤ ±0.5mm). An anti-slip rubber pad (thickness 5mm, friction coefficient ≥ 0.6, material is nitrile rubber) is pasted inside the arc-shaped groove structure. Its core function is to enhance the fit with the steel strand (≥ 90%), prevent the steel strand from slipping relative to the jacks 3 during tensioning, and ensure the effective transmission of force. The jack device also includes a dual-circuit oil supply network (the oil pipe is made of high-pressure rubber and the working pressure is ≤70MPa). The dual-circuit oil supply network realizes the pressure synchronization of multiple jacks (deviation ≤±3%) through the flow distribution valve, and the tensioning rate deviation is ≤0.5kN / s. It can accurately control the amount of tension force applied according to the preset stage to ensure the uniform transmission of force.

[0018] like Figure 1-6As shown, the steel strand unit 1 is made of steel strand, using high-strength, low-relaxation steel strand with a tensile strength ≥1860MPa (material conforming to GB / T 5224-2020 standard), and the diameter of the steel strand is 15.2-18.0mm; the middle part of the steel strand is arranged on the top support component 4 of the two jacks 3, and the two ends of the steel strand extend outward to the two ends of the load-bearing steel beam and pass through the load-bearing steel beam downward; the anchoring device 5 anchors and locks the ends of the steel strand that pass through the load-bearing steel beam. The anchoring device includes an anchor, a wedge, a thickened anchor plate, and an anti-loosening element (specific structure not shown in the figure). The thickened anchor plate is fitted onto the lower surface of the load-bearing steel beam, and a through hole is opened in the center of the thickened anchor plate for the steel strand to pass through. The anchor is a cylindrical or square steel anchor ring, with its front end face abutting against the outer end face of the thickened anchor plate. A conical hole is opened in the center of the anchor, and the taper of the conical hole matches the outer conical surface of the wedge to wedge the wedge and transmit tension. The rear end of the anchor is provided with external threads to connect the anti-loosening element. The wedge is composed of two or three wedge-shaped alloy steel plates combined to form a ring. The inner hole of the wedge is provided with reverse teeth or trapezoidal threads to directly engage the steel strand. The anti-loosening element is located at the rear end of the anchor to tighten the wedge. The anti-loosening element uses M16 8.8 grade double nuts or transverse locking bolts to reliably lock the tension at the end of the steel strand, prevent slack and slippage, and ensure long-term locking stability to meet the requirements of a construction cycle of ≥6 months.

[0019] like Figure 1 , 2 As shown, the closed-loop monitoring system includes a non-contact displacement gauge 9, a string pressure sensor 10, a strain sensor 11, a data acquisition instrument 12, and a terminal platform 13. Two sets of non-contact displacement gauges (accuracy ±0.01mm, range ±100mm) are arranged on the lower surfaces of both ends of the load-bearing steel beam. The string pressure sensor (pressure deviation ≤±3%, range 0-2000kN) is connected in series in the hydraulic circuit of the jack 3. The strain sensor 11 (accuracy ±1με, range ±5000με) is located on the upper surface of the middle section of the load-bearing steel beam. The data acquisition instrument 12 is connected to collect monitoring data from the non-contact displacement gauge 9, the string pressure sensor 10, and the strain sensor 11, and is communicatively connected to the terminal platform 13. Data is transmitted in real time to the terminal platform 13 via 4G / 5G network, which can display variables such as deflection, pressure, and strain. When the deflection exceeds L0 / 600 (L0 is the cantilever length of the support 2), the pressure deviation exceeds ±5%, or the stress deviation of the key section exceeds 10%, any of these conditions will trigger an automatic remote alarm (backend APP information push, SMS warning, telephone warning) and output a pressure fine-tuning suggestion value (accuracy ±1kN) to guide the control.

[0020] like Figure 1-6 As shown, the design method of the non-grounded formwork support frame in this embodiment includes the following steps: S1: Calculate the length of the load-bearing steel beam in support 2 L 2 and the length of the cantilever section of the load-bearing steel beam. L 0 Sufficient operating space must be reserved for the erection of support 2. The operating space on both sides of the cap beam 6 should not be less than 0.5m (one side only). The calculation formula is as follows: L 2 = L 1 +2 0.5= L 1 +1 ; in: L 1 The length of the cap beam 6 to be poured for the non-ground-supported formwork, in meters; L 3 The center-to-center distance between adjacent corbels 8 on the pier 7 is measured in meters (m).

[0021] S2: Calculate the height of the point where the tension force of the steel strand is applied. H 1 The calculation formula is as follows: ; ; in: θ The tension angle of the steel strand; L 4 The tension force of the steel strand is applied at a distance from the center of the load-bearing steel beam, in meters, and is limited to the area between the corbel anchor point and the pier column 7, i.e. ( L 3 / 2) ≤ L 4 ≤( b 0 / 2) ; b 0 Width of pier 7, in meters; H 支 The height of the jack support is in meters (m). H 千 The height of the jack is 3, in meters (m).

[0022] S3: Calculate the self-weight load of cap beam 6. G 3 The calculation formula is as follows: ; in: ρ c This represents the density of concrete, expressed in kN / m³. h 1 The height of cap beam 6 is in meters (m). b 1 The width of cap beam 6 is in meters (m).

[0023] S4: Calculate the self-weight load of the formwork for cap beam 6. G 3 The calculation formula is as follows: ; in: q m The unit area weight of the template is kN / m².

[0024] S5: Calculate the self-weight load of support 2 G 1 The calculation formula is as follows: ; in: ρ s The density of the steel in the load-bearing steel beam of support 2 is expressed in kN / m³. A 0 This represents the cross-sectional area of ​​the load-bearing steel beam, in m².

[0025] S6: Calculate the loads on construction workers and equipment. F 1 The calculation formula is: ; in: q h The value represents the standard value of construction live load, in kN / m².

[0026] S7: Calculate load combination values F s The calculation formula is as follows: .

[0027] S8: Calculate the strength of the stent. The calculation formula is as follows: ; in: S 1 The maximum stress of the load-bearing steel beam of support 2 is the bending normal stress, which needs to meet the combined verification of normal stress and shear stress. Here, it is simplified to bending normal stress as the dominant stress. W 1 The interfacial section moment of the I-beam used for load-bearing steel beams is determined by consulting the I-beam model, and the unit is m³. [ f [This refers to the design strength of the steel used in the load-bearing steel beams;] M 1 The maximum bending moment of support 2 is calculated using the following formula: M 1 =F s L 0 1.1 ; The load-bearing steel beam is calculated as a cantilever beam (cantilever end length = L0, root is the support point). The maximum bending moment M1 at the root is generated by the load combination, and the load distribution unevenness coefficient of 1.1 needs to be considered.

[0028] S9: Calculate the stiffness of bracket 2 using the following formula: ; in: D This refers to the deflection at the end of the cantilever section of the load-bearing steel beam. E The elastic modulus of the steel used in the load-bearing steel beam; I The moment of inertia of the load-bearing steel beam section is determined by consulting the I-beam model.

[0029] S10: Calculate the force required to be applied by jack 3. F D The calculation formula is: ; ; in: F T1 This is the vertical component of the tension in the steel strand; [D] represents the deflection control target value at the end of the cantilever section of the load-bearing steel beam.

[0030] S11: The tension force required to tension the steel strand, as calculated. F T2and the maximum design thrust of the jack F D-MAX The stability of the jack device is calculated using the following method: ; in: S D The maximum stress of the jack device; [ f D [This refers to the design strength of the steel used in the connection between the jack device and the load-bearing steel beam.]

[0031] ; .

[0032] like Figure 1-6 As shown, the working method of the non-grounded formwork support in this embodiment includes the following steps: (1) Complete the dimensional design of the non-ground support frame; select I-beam / double channel steel support frame, complete the support foundation assembly, use a level to calibrate the levelness, and ensure that the levelness deviation is ≤1°; (2) Based on the determined control objectives, clarify parameters such as the distance L2 from the center of the tension application node and the height H1 of the tension application node. Install the jack device according to the set position parameters, and use a laser verticality meter (accuracy ±0.01°) to calibrate the verticality of the jack to ensure that the tilt angle is ≤0.5°; install the anchoring device 5 at the preset position at the end of the support 2, adjust the position of the anchoring plate to ensure that it is compatible with the end of the steel strand; set up a closed-loop monitoring system, with the non-contact displacement meter 9 set at the lower edge of the end of the cantilever steel beam, the string pressure sensor 10 set at the bottom of the jack 3, the top of the sand box and the anchoring end of the steel strand unit 1, and the strain sensor 11 set at the section with the maximum negative bending moment. Complete the communication connection and parameter debugging between the data acquisition instrument 12 and the terminal platform 13.

[0033] (3) Tensioning system construction: Install tension steel strands according to the design layout, pass one end of the steel strand through the anchor of the anchoring device 5, install the anchor stress sensor and clamp it, and set the other end in the top roller groove of the jack 3. Use the through-type jack to adjust the tension of the steel strand to ensure that the steel strand is tensioned and locked in the groove; check the connection status of each component to form a complete force transmission system of "steel strand-jack-anchoring system" to ensure that the functions of each component are coordinated.

[0034] (4) Initiate the symmetrical synchronous tensioning process, applying tension force in three stages: graded tensioning, load holding and stabilization, and locking. At the same time, the pressure, strain, and deflection data (deflection D1 at the end of the cap beam 6, maximum stress S1 at the root of the cantilever of the load-bearing main beam of the support 2, load sensor force F2 at the corbel 8, and load F3 applied by the tensioning cable, etc.) need to be monitored synchronously with the pressure of the jack 3 and the deflection data of the steel strand and the support 2. The core function is to ensure that the tension force is matched with the deformation state and to avoid local stress concentration (stress value ≤ 80% of the yield strength of the steel) or exceeding the standard caused by the imbalance of "force-shape" in the support.

[0035] (5) Performance verification and dynamic control: After tensioning, the stability, axial force of cap beam 6, bending moment at the root of cap beam 6, and deflection at the end of cap beam 6 are read and calculated by non-contact displacement meter 9 to ensure that the deflection is ≤L / 600. If the indicators do not meet the standards, the pressure of jack 3 is adjusted to ≤3% of the design tension force according to the pressure adjustment suggestion value output by terminal platform 13. After each adjustment, the pressure is left to stand for 2 minutes and the indicators are tested again until all indicators are qualified. The functional status of the components is continuously monitored throughout the process, and the monitoring data is recorded to form a construction archive.

[0036] The beneficial effects of this embodiment are as follows: (1) Compared with traditional steel supports, the stiffness of the supports is increased by 20%-30% (up to 5×10) through the coordinated force sharing between the steel strand units and the I-beam supports. 5 With a deflection control accuracy of ±0.01mm (above kN / m), it can adapt to the construction environment of cantilever cap beams with large spans and high loads. (2) Compared with the traditional support construction process, the design method is carried out in accordance with the standardized process of "target setting-deployment-building-tensioning-verification", and the core components (jack device, steel strand, anchoring device) adopt modular design, which shortens the assembly time by 20% and can effectively improve construction efficiency. (3) Compared with traditional supports, the use of tension strengthening technology replaces part of the steel, thereby reducing the amount of steel used and lowering costs; (4) Compared with traditional support systems, this device can be reused repeatedly and has better energy-saving and environmental protection performance; (5) Compared with the traditional "manual monitoring" of the support, the closed-loop monitoring system realizes real-time acquisition of multi-dimensional data (deflection, pressure, tilt angle), and the response time of exceeding the limit is ≤1s. It automatically outputs control suggestions, avoids construction risks caused by human misjudgment, and improves construction safety by more than 50%. (6) Compared with the traditional "heavy steel stacking" support, the tension strengthening technology replaces some heavy steel, and the core components are designed to be lightweight (such as jacks weighing ≤50kg / unit), which can reduce the overall load of the support during high-altitude construction and is suitable for lightweight construction platforms such as climbing formwork and hanging baskets.

Claims

1. A non-grounded formwork support with controllable deflection using tensioned wire, characterized in that... The non-grounded formwork support includes a support frame, a jacking device, a steel strand unit, and an anchoring device; wherein: The support frame is installed on top of the pier column. The support frame includes two transverse load-bearing steel beams and several longitudinal connecting rods. Corbels are installed at both ends of the longitudinal direction of the pier column, and the two load-bearing steel beams are supported and fixed by the corbels at both ends of the longitudinal direction. The connecting rods are installed between the two load-bearing steel beams to connect and form the support frame as a whole. The middle area of ​​the load-bearing steel beam is located above the pier column, and the two ends of the load-bearing steel beam extend outward from the area of ​​the pier column. The load-bearing steel beam is equipped with the jack device, the steel strand unit, and the anchoring device; the jack device includes two jacks, the bottoms of which are fixedly supported in the middle area of ​​the load-bearing steel beam; the top of the jacks is provided with a top support component, which adopts an arc-shaped groove structure. The steel strand unit is made of steel strands, the middle of which is arranged on the top support assembly of the two jacks, and the two ends of the steel strands extend outward to the two ends of the load-bearing steel beam and pass downward through the load-bearing steel beam. The anchoring device anchors and locks the steel strand through the end of the load-bearing steel beam.

2. The non-grounded formwork support with controllable deflection using tensioned wire as described in claim 1, characterized in that... An anti-slip rubber pad is attached to the arc-shaped groove structure of the top support component, and the friction coefficient of the anti-slip rubber pad is ≥0.

6.

3. A non-grounded formwork support frame with controllable deflection using tensioned wire, as described in claim 1, is characterized in that... The anchoring device includes an anchor, a wedge, a thickened anchor plate, and an anti-loosening element. The thickened anchor plate is fitted onto the lower surface of the load-bearing steel beam, and a through hole is provided in the center of the thickened anchor plate for the steel strand to pass through. The anchor is a cylindrical or square steel anchor ring, with its front end face abutting against the outer end face of the thickened anchor plate. A tapered hole is provided in the center of the anchor, the taper of which matches the outer tapered surface of the wedge to wedge the wedge and transmit tension. The rear end of the anchor is provided with an external thread to connect to the anti-loosening element. The wedge is composed of two or three wedge-shaped alloy steel plates forming a ring, and the inner hole of the wedge is provided with reverse teeth or trapezoidal threads to directly engage the steel strand. The anti-loosening element is provided at the rear end of the anchor to press against the wedge.

4. A non-grounded formwork support with controllable deflection using tensioned wire as described in claim 1, characterized in that... The non-grounded formwork support also includes a closed-loop monitoring system, which comprises non-contact displacement gauges, string pressure sensors, strain sensors, a data acquisition instrument, and a terminal platform. Two sets of non-contact displacement gauges are arranged on the lower surfaces of both ends of the load-bearing steel beam. The string pressure sensors are connected in series in the hydraulic circuit of the jack. The strain sensors are located on the upper surface of the middle section of the load-bearing steel beam. The data acquisition instrument is connected to collect monitoring data from the non-contact displacement gauges, string pressure sensors, and strain sensors, and is communicatively connected to the terminal platform.

5. A design method for a non-grounded formwork support with controllable deflection using tensioned wire, as described in any one of claims 1-4, characterized in that... The design method includes the following steps: S1: Calculate the length of the load-bearing steel beam in the support structure. L 2 and the length of the cantilever section of the load-bearing steel beam. L 0 The calculation formula is as follows: L 2 = L 1 +2 0.5= L 1 +1 ； in: L 1 The length of the cap beam to be poured for the aforementioned non-grounded formwork support; L 3 The center-to-center distance between adjacent corbels on the pier; S2: Calculate the height of the point where the tension force of the steel strand is applied. H 1 The calculation formula is as follows: ； in: θ The tension angle of the steel strand; L 4 The tension force applied to the steel strand is limited to the distance from the center of the load-bearing steel beam to the node, within the range between the corbel anchor point and the pier column, i.e. ( L 3 / 2) ≤ L 4 ≤( b 0 / 2) ; b 0 The width of the pier column; S3: Calculate the self-weight load of the cap beam. G 3 The calculation formula is as follows: ； in: ρ c This refers to the density of concrete. h 1 The height of the cap beam; b 1 The width of the cap beam; S4: Calculate the self-weight load of the formwork for the cap beam. G 3 The calculation formula is as follows: ； in: q m The weight per unit area of ​​the template; S5: Calculate the self-weight load of the support. G 1 The calculation formula is as follows: ； in: ρ s The density of the steel in the load-bearing steel beam of the bracket; A 0 The cross-sectional area of ​​the load-bearing steel beam; S6: Calculate the loads on construction workers and equipment. F 1 The calculation formula is: ； in: q h This refers to the standard value of construction live load; S7: Calculate load combination values F s The calculation formula is as follows: ； S8: Calculate the strength of the support, using the following formula: ； in: S 1 The maximum stress is the load-bearing steel beam of the support frame; W 1 The interfacial modulus of the I-beam used for the load-bearing steel beam is determined by consulting the I-beam model. [ f The design strength of the steel used in the load-bearing steel beam is [not specified]. M 1 The maximum bending moment of the support is calculated using the following formula: M 1 =F s L 0 1.1 ; S9: Calculate the stiffness of the support, using the following formula: ； in: D The deflection at the end of the cantilever section of the load-bearing steel beam; E The elastic modulus of the steel in the load-bearing steel beam is given. I The moment of inertia of the load-bearing steel beam section is determined by consulting the I-beam model. S10: Calculate the force required to be applied by the jack. F D The calculation formula is: ； ； in: F T1 This is the vertical component of the tension force of the steel strand; [D] represents the deflection control target value at the end of the cantilever section of the load-bearing steel beam; S11: The tension force required to tension the steel strand, as calculated. F T2 and the maximum design thrust of the jack F D-MAX The stability of the jack device is calculated using the following method: ； in: S D The maximum stress of the jack device; [ f D The design strength of the steel used in the connection between the jack device and the load-bearing steel beam is specified. ； 。

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