A steel strand counter pull rod
By using steel strand tie rods, combined with PVC sleeves and adjusting bolt assemblies, the problem of traditional tie rods being unable to be removed was solved, enabling material reuse, ensuring construction safety and reliability, and reducing project costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HONGRUN CONSTRUCTION GROUP CO LTD
- Filing Date
- 2025-08-19
- Publication Date
- 2026-07-14
Smart Images
Figure CN224495809U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of tie rod technology for structural concrete formwork, and in particular to a steel strand tie rod. Background Technology
[0002] In engineering construction, tie rods are typically used for fixing formwork and preventing concrete bulging. Traditional construction techniques use round steel or precision-rolled threaded steel as tie rods for structural formwork fixing. While their strength and rigidity meet construction requirements, they also have significant drawbacks. Because round steel or precision-rolled threaded steel tie rods cannot be bent, their working surface is restricted by surrounding obstacles during structural construction. Therefore, even with sleeves, the tie rods cannot be pulled out, making them virtually impossible to remove during formwork dismantling, requiring severing. Leaving tie rods behind not only affects the quality of structural construction but also creates corrosion channels within the structure. This is particularly problematic for structures located in unprotected marine environments, severely compromising their durability. Furthermore, frequent instances of leftover tie rods increase construction costs and result in significant resource waste. Therefore, it is essential to improve and innovate traditional construction techniques to ensure solid and aesthetically pleasing concrete construction, providing a guarantee for safe operation later on. Utility Model Content
[0003] The purpose of this invention is to provide a steel strand tie rod to solve the problems existing in the prior art.
[0004] To achieve the above objectives, this utility model provides the following solution: This utility model provides a steel strand tie rod, including a steel strand tie rod penetrating a template. One end of the steel strand tie rod extending out of the template is fitted with a PVC sleeve. The other end of the steel strand tie rod is sequentially fitted with a template pad, a template back rib, a pad, a tie rod length adjusting bolt, and a locking assembly. The template pad is positioned close to the template. The tie rod length adjusting bolt is used to adjust the length of the steel strand tie rod. The locking assembly is used to lock the steel strand tie rod and is positioned at the end of the tie rod length adjusting bolt away from the template.
[0005] Preferably, the inner diameter of the PVC sleeve of the steel strand tie rod is adapted to the outer diameter of the steel strand tie rod.
[0006] Preferably, the template pad has a reserved hole for the steel strand tie rod to pass through.
[0007] Preferably, the template pad, the template back rib, and the pad are each provided with a reserved hole for the steel strand tie rod to pass through.
[0008] Preferably, the tie rod length adjusting bolt includes a screw rod, one end of which passes through the pad and extends into the template back rib, and the other end of the screw rod passes through and is fixedly connected to an end fixing nut.
[0009] Preferably, a movable nut is threaded onto the screw.
[0010] Preferably, the screw has a hole for the steel strand tie rod to pass through, and the central axis of the hole is on the same central axis as the central axis of the screw.
[0011] Preferably, the central axis of the hole and the central axis of the reserved hole are on the same central axis.
[0012] Preferably, the locking assembly includes an anchor sleeved on the steel strand tie rod, and a tool clamp is detachably connected to the end of the anchor away from the end fixing nut.
[0013] The present invention discloses the following technical effects:
[0014] The steel strand tie rod of this utility model can be reused repeatedly, effectively avoiding material waste; at the same time, it also has a certain strength to ensure stable operation under the action of concrete lateral pressure, vibration impact force, etc.; while being sturdy, it also has a certain degree of flexibility, making it easy to pull out, so that the installation and removal of the steel strand tie rod is convenient and quick.
[0015] This invention effectively reduces project costs, prevents resource waste, eliminates quality defects, leaves no hidden dangers for later operation, and ensures safe and reliable construction while being easy to operate. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a schematic diagram of the overall structure of this utility model;
[0018] Figure 2 This is a cross-sectional view of the template pad of this utility model;
[0019] Figure 3 This is a side view of the template pad structure of this utility model;
[0020] Figure 4 This is a front view schematic diagram of the length adjusting bolt of this utility model;
[0021] Figure 5 This is a side sectional view of the length adjusting bolt of this utility model.
[0022] Among them, 1. Steel strand tie rod; 2. Template; 3. Template pad; 4. Template back rib; 5. Pad; 6. PVC sleeve of steel strand tie rod; 7. Tie rod length adjustment bolt; 8. Anchor; 9. Tool clamp; 31. Reserved hole; 71. Screw rod; 72. End fixing nut; 73. Adjustable nut; 74. Hole. Detailed Implementation
[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0024] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0025] Reference Figures 1-5 This utility model discloses a steel strand tie rod, including a steel strand tie rod 1 that penetrates through a template 2. One end of the steel strand tie rod 1 extending out of the template 2 is fitted with a steel strand tie rod PVC sleeve 6. The other end of the steel strand tie rod 1 is sequentially fitted with a template pad 3, a template back rib 4, a pad 5, a tie rod length adjusting bolt 7, and a locking assembly. The template pad 3 is located close to the template 2. The tie rod length adjusting bolt 7 is used to adjust the length of the steel strand tie rod 1. The locking assembly is used to lock the steel strand tie rod 1. The locking assembly is located at the end of the tie rod length adjusting bolt 7 away from the template 2.
[0026] The steel strand tie rod 1 of this utility model can be reused repeatedly, effectively avoiding material waste; at the same time, it also has a certain strength to ensure that it can work stably under the action of concrete lateral pressure, vibration impact force, etc.; while being sturdy, it also has a certain degree of flexibility, making it easy to pull out, so that the installation and removal of the steel strand tie rod 1 is convenient and quick.
[0027] This invention effectively reduces project costs, prevents resource waste, eliminates quality defects, leaves no hidden dangers for later operation, and ensures safe and reliable construction while being easy to operate.
[0028] The design was further optimized so that the inner diameter of the PVC sleeve 6 for the steel strand tie rod is matched with the outer diameter of the steel strand tie rod 1. This allows the steel strand tie rod 1 to be effectively inserted into the PVC sleeve 6.
[0029] To further optimize the design, a pre-drilled hole 31 is provided on the template base plate 3 for the steel strand tie rod 1 to pass through. The template base plate 3 is made of 1cm thick steel plate, and the diameter of the pre-drilled hole 31 is 4c.
[0030] The design was further optimized by providing pre-drilled holes 31 on the template base plate 3, template back rib 4, and base plate 5 for the steel strand tie rod 1 to pass through. The base plate 5 is an A3 steel plate with dimensions of 15×15cm.
[0031] The design has been further optimized. The tie rod length adjusting bolt 7 includes a screw 71. One end of the screw 71 passes through the pad 5 and extends into the template back rib 4. The other end of the screw 71 passes through and is fixedly connected to an end fixing nut 72. The tie rod length adjusting bolt 7 is made of M35 high-strength bolt, and the maximum adjustable length is 4cm.
[0032] The design was further optimized by adding a movable nut 73 to the screw 71.
[0033] In a further optimized design, the screw 71 has a hole 74 for the steel strand tie rod 1 to pass through, and the central axis of the hole 74 is on the same central axis as the central axis of the screw 71. The diameter of the hole 74 is 16mm.
[0034] The scheme was further optimized so that the central axis of hole 74 and the central axis of reserved hole 31 are on the same central axis.
[0035] A further optimized design includes an anchor 8 fitted onto the steel strand tie rod 1, with a tool clamp 9 detachably connected to the end of the anchor 8 away from the end fixing nut 72. Both the anchor 8 and the tool clamp 9 are single-hole types.
[0036] Work process: The installation method of steel strand to tie rod includes the following steps:
[0037] S1. Determine the length of the steel strand tie rod 1 according to the structural dimensions of the concrete to be poured; then process and cut it according to the calculated length.
[0038] S2. Install template 2 and temporarily fix it in place; so that template 2 can be installed effectively.
[0039] S3. Install steel strand tie rod PVC sleeve 6 between two opposite templates 2; so that the steel strand tie rod PVC sleeve 6 can effectively extend into the through holes on the two opposite templates 2.
[0040] S4. Insert the steel strand tie rod 1 into the PVC sleeve 6 of the steel strand tie rod, and make both ends of the steel strand tie rod 1 extend out of the template 2 respectively; and reinforce the internal support of the template 2.
[0041] S5. Install template pad 3, template back rib 4, pad 5, tie rod length adjusting bolt 7 and locking assembly sequentially on the end of the steel strand tie rod 1 that extends out of the template 2; to facilitate tensioning of the steel strand tie rod 1.
[0042] S6. Tension the steel strand tie rod 1 and adjust its length using the tie rod length adjusting bolt 7 to bring it into a stressed state. After verifying the dimensions and stress condition, concrete pouring can begin.
[0043] This invention accurately calculates the design tensile force required at each tie rod position based on factors such as concrete lateral pressure, structural characteristics, formwork height, pouring speed, and construction load.
[0044] Based on the design tensile force and considering a safety factor (typically ≥1.5~2.0), select steel strand tie rods of appropriate specifications and number. Ensure that their ultimate tensile strength safety factor is sufficient.
[0045] The strength of the anchor 8 itself, the bearing pressure under the anchor (local bearing pressure strength of concrete), and the strength and stiffness of the pad 5 are verified to ensure the safety of all components under the maximum design tensile force.
[0046] The theoretical elongation is calculated based on the elastic modulus, cross-sectional area, effective free length (distance between the inner sides of the two anchors 8) of the steel strand tie rod 1 and the design tension (or pretension).
[0047] The purpose of applying prestress is to compensate for potential relaxation caused by factors such as concrete shrinkage and creep, compression deformation of the PVC sleeve 6 of the steel strand tie rod, and slight deformation of the formwork 2, ensuring that the steel strand tie rod 1 always provides effective tension before the concrete hardens and controlling the deformation of the formwork 2. This is generally carried out after the steel strand tie rod 1 is installed in place, the formwork 2 is finally tightened, and before concrete pouring.
[0048] The tension value is usually taken as 10% to 30% of the design tension value. The specific value should be determined based on calculation, test or experience, and the slack of the steel strand tie rod 1 should be taken into account.
[0049] Tensioning is performed using calibrated hydraulic jacks and matching pressure gauges or sensors. Strict "dual control" is implemented according to the calculated pretension and elongation values. It is determined whether the design requires the recovery of the steel strand tie rod 1.
[0050] If it is recyclable, the installation of the PVC sleeve 6 for the isolation steel strand tie rod, end treatment, and disassembly of the anchor 8 must ensure that the steel strand tie rod 1 can be pulled out smoothly.
[0051] Key construction points:
[0052] 1) Construction Preparation: Thoroughly review the design drawings and technical requirements. Develop a specialized construction plan, clearly defining materials, processes, procedures, safety measures, and personnel allocation. Inspect incoming materials (steel strands, anchors, sleeves, accessories, etc.) and provide certificates of conformity. Perform equipment calibration (jacks, oil pumps, pressure gauges).
[0053] 2) Measurement and Layout: Strictly follow the design drawings to accurately locate the points where the tie rods (steel strands) pass through the template. Considering the thickness of template 2, lay out the corresponding positions on the opposite template 2 to ensure the holes are aligned.
[0054] 3) Drilling holes in template 2: Use a special drill bit to drill holes at the layout location. The hole diameter must be larger than the maximum outer diameter of the PVC sleeve 6 of the steel strand tie rod or the anchor 8, usually 5-10mm larger than the outer diameter of the PVC sleeve 6 of the steel strand tie rod, to ensure smooth insertion and effective sealing. The hole position deviation should be controlled within a certain range (e.g., ±5mm). Clean the burrs from the hole edges.
[0055] 4) Anchor installation: According to the design requirements, install fixed end anchors (such as fixed end compression anchors / P anchors) and movable end anchors (such as tool clamps 9) on the outside of the template 2; ensure that the contact surface between the anchor 8 and the template pad 3 is flat and clean, and that the template pad 3 is in close contact with the template 2.
[0056] 5) Installation of the isolation sleeve (installation of the PVC sleeve 6 for the steel strand tie rod): The steel strand must be completely encased in the isolation sleeve during the tensioning section (between the two anchor points). The sleeve length must be greater than the free length of the steel strand (both ends should extend a certain distance beyond the inner end face of the anchor 8, such as 150-300mm). Consider the thickness of the template 2 and the length of the anchor 8.
[0057] 6) Sealing treatment: After the sleeve passes through the through hole of template 2, use a reliable sealant (such as foaming agent, custom sealing plug + glue) to seal the gap between the sleeve and the hole wall of template 2 to ensure no grout leakage during pouring. The sleeve end on the side of anchor 8 should also be properly sealed (such as with tape) to prevent cement grout from splashing in during pouring.
[0058] 7) Threading the steel strand: Carefully thread the steel strand through the sleeve and the installed anchor hole to avoid the steel strand getting tangled or scratching the sleeve, and ensure that the steel strand is free and unrestrained inside the sleeve.
[0059] 8) Installation of anchorage at the movable end (tensioning end): Install tool clamp 9 at the movable end where the steel strand has been threaded, and tighten it initially with a special tool or small jack.
[0060] 9) Apply pretension: Install jacks (which must be compatible with the steel strands and anchors). Tension the strands in stages according to the plan (e.g., 0 → initial stress (record elongation) → pretension force → holding load). For multiple steel strands, overall tensioning is generally used.
[0061] 10) Dual control: Primarily controlled by oil pressure gauge readings, and verified by measuring the elongation of the steel strand. The difference between the actual elongation and the theoretical value should be within ±6%.
[0062] 11) Anchoring: After reaching the predetermined tension and elongation values, tighten the locking tool clamp 9. Slowly release the pressure from the jack.
[0063] 12) Records: Record in detail the tension, elongation, holding time, and operator of each tie rod.
[0064] 13) End protection: Exposed steel strand ends (especially movable ends) must be immediately protected with reliable temporary protection and safety warning signs (such as warning caps and protective sleeves).
[0065] 14) Rust prevention: Take temporary rust prevention measures for anchorages and steel strand ends that are exposed for a long time (not recycled).
[0066] 15) Concrete pouring: Pay close attention to the stability of the formwork to ensure that there is no abnormal deformation or formwork displacement; avoid the tie rod position during vibration operation to prevent direct impact on the tie rod, sleeve and seal.
[0067] 16) Formwork removal and tie rod treatment: Formwork 2 and steel strand tie rod 1 can only be removed after the concrete strength reaches the design strength (or specification requirements).
[0068] 17) Disassembly sequence: Remove the end protection facilities; remove the outer nut (if any), limit plate (if any), and tool clamp 9 (special tools required) of the movable end anchor.
[0069] 18) Recovery: Gently tap the loosened end of the steel strand, then manually or with a small winch, pull the steel strand out of the sleeve at a uniform speed and straight. If the resistance is too great, stop and check the cause (such as grout leakage or blockage).
[0070] 19) Non-recyclable: If the design does not allow for the recycling of the steel strands (e.g., for permanent anchoring), the steel strands must be cut and ground flat near the concrete surface inside the anchor (≥50mm). Direct cutting at the outside of the tensioning end is strictly prohibited to prevent loosening and rebound that could cause injury.
[0071] Specific implementation notes:
[0072] 1) The steel strand must conform to relevant national standards (such as GB / T5224 "Steel Strand for Prestressed Concrete"); the commonly used specification is 1×7 standard type (such as Φ15.2mm, 1860MPa grade or higher strength grade); the surface should be clean, free from rust, oil stains, cracks, severe scratches and dead bends. Slight surface rust should be removed before use; ensure low relaxation performance.
[0073] 2) The anchoring system must use specialized tension anchors that match the specifications of the steel strands and have passed quality certification. Common types include: single-hole anchors (clamp type), extrusion anchors (P-anchors), and embossed anchors. The selection depends on factors such as design tension, space constraints, and whether recycling is required. The anchors should have reliable anchoring performance, sufficient strength and stiffness (to avoid anchor plate deformation). The size, thickness, and stiffness of the matching anchor plates must meet the requirements to ensure effective stress diffusion and avoid localized crushing of the concrete.
[0074] 3) The entire tensioning section of the steel strand must be covered with a reliable isolation sleeve (PE pipe, PVC pipe, etc.) to ensure effective isolation between the steel strand and the concrete, facilitating later removal and recovery of the tensioning section; preventing concrete from binding the steel strand, which could lead to irremovability or stress loss; the sleeve strength should be able to withstand the impact of pouring and vibration; it should have good sealing performance to prevent cement slurry from seeping in; the inner diameter should be 10-20mm larger than the diameter of the steel strand; and the joints should be reliably sealed (by wrapping with tape or hot-melt).
[0075] 4) The end of the sleeve must be sealed to the template to prevent grout leakage. Materials such as foaming agent, special sealing plug, rubber gasket and sealant can be used.
[0076] 5) Before tensioning the prestressed tie rods, the anchors and wedges should be checked repeatedly to ensure that they are firmly installed before tensioning can be carried out. At the same time, the inside of the template should also be reinforced before tensioning.
[0077] 6) When tensioning prestressed tie rods, workers should be prevented from working directly in front of the prestressed tie rods, and unauthorized personnel should be reminded not to approach.
[0078] 7) When pouring concrete, avoid direct impact of concrete on the steel strand tie rod as much as possible. Do not use a vibrator to touch the steel strand tie rod. Pay close attention to the condition of the steel strand tie rod. In case of emergency, stop construction and continue construction only after checking and confirming that there are no problems.
[0079] 8) When dismantling prestressed tie rods, workers should be prevented from working directly in front of the prestressed tie rods, and unauthorized personnel should be reminded not to approach.
[0080] 9) To prevent pinching your hand, you must first use a tool to loosen the length adjuster until the tensioned prestressed tie rod is free of prestress.
[0081] This invention uses prestressed steel strand as the tie rod, which has the following advantages compared to traditional round steel and precision-rolled threaded steel tie rods:
[0082] ① The material is readily available; ② The material is flexible, allowing for installation and removal even when the working surface is restricted by surrounding obstacles during structural construction. It is also easy to pull out when removing the formwork; ③ It is recyclable, reducing costs and preventing resource waste; ④ Pre-tensioning force can be applied during tie rod installation to offset concrete and construction loads, ensuring that the formwork does not deform and that the concrete appearance and dimensions meet the standards; ⑤ Compared with traditional steel tie rods, steel strands have advantages such as high strength, good toughness, and ease of applying prestress over long distances.
[0083] In the description of this utility model, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0084] The embodiments described above are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Various modifications and improvements made to the technical solutions of the present utility model by those skilled in the art without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.
Claims
1. A steel strand tie rod, characterized in that: The system includes a steel strand tie rod (1) that penetrates the template (2). One end of the steel strand tie rod (1) extending out of the template (2) is fitted with a steel strand tie rod PVC sleeve (6). The other end of the steel strand tie rod (1) is fitted with a template pad (3), a template back rib (4), a pad (5), a tie rod length adjusting bolt (7), and a locking assembly in sequence. The template pad (3) is located close to the template (2). The tie rod length adjusting bolt (7) is used to adjust the length of the steel strand tie rod (1). The locking assembly is used to lock the steel strand tie rod (1). The locking assembly is located at the end of the tie rod length adjusting bolt (7) away from the template (2).
2. The steel strand tie rod according to claim 1, characterized in that: The inner diameter of the PVC sleeve (6) of the steel strand tie rod is adapted to the outer diameter of the steel strand tie rod (1).
3. The steel strand tie rod according to claim 1, characterized in that: The template pad (3) has a reserved hole (31) for the steel strand tie rod (1) to pass through.
4. The steel strand tie rod according to claim 1, characterized in that: The template pad (3), the template back rib (4), and the pad (5) are respectively provided with reserved holes (31) for the steel strand tie rod (1) to pass through.
5. The steel strand tie rod according to claim 4, characterized in that: The tie rod length adjusting bolt (7) includes a screw (71), one end of which passes through the pad (5) and extends into the template back rib (4), and the other end of the screw (71) passes through and is fixedly connected to an end fixing nut (72).
6. The steel strand tie rod according to claim 5, characterized in that: A movable nut (73) is threaded onto the screw (71).
7. The steel strand tie rod according to claim 5, characterized in that: The screw (71) has a hole (74) for the steel strand tie rod (1) to pass through, and the central axis of the hole (74) is on the same central axis as the central axis of the screw (71).
8. The steel strand tie rod according to claim 7, characterized in that: The central axis of the hole (74) and the central axis of the reserved hole (31) are on the same central axis.
9. The steel strand tie rod according to claim 5, characterized in that: The locking assembly includes an anchor (8) sleeved on the steel strand tie rod (1), and a tool clamp (9) is detachably connected to one end of the anchor (8) away from the end fixing nut (72).