A device for relieving shrinkage stress in concrete towers and its construction method

Abstract

This invention relates to a shrinkage stress relief device for concrete towers and its construction method. The device includes a filler and circumferential reinforcement. The filler is provided at the circumferential joint of the tower sections. The filler is made of a high-ductility fiber-reinforced cementitious composite material. The filler is connected to the tower sections through internal circumferential reinforcement. The device is obtained by first casting the filler and binding the circumferential reinforcement, and then casting the tower sections after installing the device. Compared with the prior art, this invention can prevent unnecessary shrinkage damage to the concrete tower sections during the production process and prevent the tower sections from cracking due to shrinkage stress.

Description

Technical Field

[0001] This invention belongs to the field of ultra-high tower construction technology, and relates to a device for relieving shrinkage stress in concrete towers and its construction method. Background Technology

[0002] With the rapid development of the wind power industry, the total installed capacity of wind power generation is constantly increasing, and the capacity of single units is increasing from hundreds of kilowatts to multi-megawatt levels, placing higher demands on wind turbine towers. Currently, prefabricated concrete towers have become the mainstream choice in the wind power industry. During the production process of monolithic concrete towers, the inevitable creep and shrinkage of concrete will generate tensile stress along the circumferential direction of the tower, causing cracks to appear in the weak circumferential sections of the concrete tower. If no measures are taken to effectively control the cracks, allowing them to further develop to exceed the limits that concrete can withstand, or even form through cracks, it will seriously affect the structural performance and threaten the structural durability and waterproofing properties.

[0003] Patent CN118517374A discloses a prestressed honeycomb steel-concrete composite structure tower and its construction method. The tower includes a cylinder body, which is assembled from several cylinder segments along its height, with the diameter of each segment decreasing from low to high. Adjacent cylinder segments are connected by vertical nodes, and each cylinder segment is connected circumferentially by several prestressed steel-concrete shells through circumferential nodes. The circumferential nodes include circumferential connecting steel at both ends of the shell, high-strength bolts evenly arranged along the height of the shell, and filling material inside the circumferential connecting steel. The high-strength bolts and the circumferential connecting steel achieve the connection between adjacent prestressed steel-concrete shells circumferentially. However, this patent describes a steel-concrete composite structure composed of circumferential connecting steel and filling material, which has high cost, complex construction process, and long construction period. Furthermore, the use of cement-based composite materials for filling in a fully cast-in-place project significantly increases the material cost of the tower segments.

[0004] Patent CN115787482A discloses a construction method for prefabricated composite beams, including the following steps: Step 1, fabrication of precast concrete bridge decks, with concave-convex shear grooves, grouting holes, and grout outlet holes set at the haunches; Step 2, processing and assembly of steel beams, welding group stud connectors to the upper flanges of the steel beams; Step 3, installation of precast concrete bridge decks, placing long welding studs into the grouting holes and grout outlet holes, and short welding studs into the protruding key teeth of the concave-convex shear grooves; Step 4, filling of the concave-convex shear grooves; Step 5, pouring of transverse and longitudinal wet joints between precast concrete bridge decks, after the cement-based filler in the concave-convex shear grooves has initially hardened, binding reinforcing bars in the transverse and longitudinal wet joints between the precast concrete bridge decks and pouring fiber-reinforced high-strength concrete. However, the precast bridge decks in this patent have cast-in-place wet joints, which cannot meet the requirements for rapid construction of concrete tower sections; furthermore, the use of fiber-reinforced high-strength concrete in the joints of this patent cannot fulfill the function of releasing shrinkage stress in the tower sections. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one of the defects in the prior art by providing a concrete tower shrinkage stress relief device and its construction method. This invention can prevent unnecessary shrinkage damage to concrete tower sections during the production process and prevent the tower sections from cracking due to shrinkage stress.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a shrinkage stress relief device for a concrete tower. The device includes a filler and circumferential reinforcement. The tower section is provided with a filler at the circumferential joint. The filler is made of a high ductility fiber-reinforced cementitious composite material (engineering cementitious composite, ECC). The filler is connected to the tower section through the internal circumferential reinforcement. The device is obtained by first casting the filler and binding the circumferential reinforcement, and then the tower section is cast after the device is installed.

[0008] The filler and circumferential reinforcement are combined as prefabricated components for stress relief. The circumferential reinforcement serves as the structural reinforcement for the prefabricated filler joint and the lap reinforcement for bonding with the main body of the tower plate. It aims to improve the defects of concrete shrinkage cracking that are unavoidable in the production process of prefabricated integral tower plates. It can not only ensure the overall performance of the concrete tower plates and meet the structural bearing capacity requirements, but also effectively release the shrinkage stress during the production process of the tower plates due to the low elastic modulus of the high ductility fiber-reinforced cement-based composite material and the fact that cracking does not affect durability.

[0009] Furthermore, the tower plate is an integral tower plate, which has a gap reserved at the circumferential joint position, and the gap is filled with a filling material.

[0010] During the hardening process, concrete shrinks in volume due to moisture evaporation (drying shrinkage) and cement hydration reaction (chemical shrinkage). Even under ideal curing conditions, moisture loss can still cause irreversible shrinkage deformation. Monolithic towers are usually large-volume structures, and the heat of hydration inside is difficult to dissipate quickly after pouring, resulting in a temperature difference between the inside and outside. The tensile stress caused by the temperature gradient during cooling will exacerbate shrinkage cracks. During the production of monolithic concrete towers, creep shrinkage of concrete is inevitable. Therefore, the high ductility fiber-reinforced cementitious composite material in this invention is needed to release shrinkage stress.

[0011] Furthermore, the curvature of the circumferential joint should account for 2-5% of the overall tower section. If it is too small, it will be inconvenient for construction and stress release; if it is too large, it will be uneconomical.

[0012] Furthermore, the high-ductility fiber-reinforced cementitious composite material comprises a solid component and a liquid component, wherein the liquid component is water, and the water-cement ratio of the liquid component to the solid component is 0.6-0.8. The solid component comprises the following components in parts by weight:

[0013] 100 parts cement, 50-100 parts mineral admixtures, 50-70 parts fine aggregates, 1-10 parts fiber and 1-3 parts water-reducing agent.

[0014] As a preferred technical solution, the cement is a cementitious material that forms cement stone through a hydration reaction, binding other components together and providing initial strength and basic bonding properties. During the hydration process, cement particles react chemically with water to produce various hydration products, which fill the internal pores of the material, gradually harden, and enhance the overall structure of the material, which is the basis for the material to obtain strength.

[0015] As a preferred technical solution, the mineral admixture is selected from one or more of fly ash, silica fume, and slag powder. The fly ash particles are fine and can fill the gaps between cement particles, increase the density of the material, improve workability, and can also undergo a secondary reaction with cement hydration products to improve the later strength of the material. The silica fume has extremely high pozzolanic activity and can quickly react with calcium hydroxide produced by cement hydration to generate more gel substances, significantly improving the early and later strength of the material, while enhancing the durability and impermeability of the material. The slag powder undergoes a hydration reaction under the alkaline activation of cement hydration products, increasing the amount of hydration products and improving the later strength of the material.

[0016] As a preferred technical solution, coarse aggregate is used less in high-ductility fiber-reinforced cementitious composites. Fine aggregate with smaller particle size is mainly used, which mainly plays the role of reducing shrinkage and improving wear resistance. The fine aggregate is selected from one or more of iron ore fine aggregate, quartz sand, river sand, and manufactured sand. The quartz sand can fill the voids between cement pastes, reduce the porosity inside the material, improve the density of the material, and enhance the volume stability of the material, which has an important impact on the strength and durability of the composite material.

[0017] As a preferred technical solution, the fibers are uniformly dispersed in the cement matrix, which can effectively prevent the generation and development of microcracks. When the material is subjected to external force, the fibers can bear part of the load, playing a role in reinforcement and toughening, and giving the material high ductility. The fibers are selected from one or more of polyvinyl alcohol (PVA) fibers, polypropylene (PP) fibers, and steel fibers. The polyvinyl alcohol fibers have good bonding performance with the cement matrix. When the material is under tension, they can effectively inhibit the propagation of cracks and improve the tensile strain capacity and toughness of the material.

[0018] As a preferred technical solution, the water-reducing agent is essential for reducing the amount of mixing water and improving the fluidity of the material.

[0019] Furthermore, the preparation method of the high-ductility fiber-reinforced cementitious composite material includes the following steps:

[0020] S1.1 Add cement, mineral admixtures and fine aggregates to a mixer and mix at low speed to ensure uniformity and no lumps, to obtain dry material;

[0021] S1.2 Slowly add the water-reducing agent and water to the dry material and mix them. Stir at medium speed to form a uniform slurry and obtain the wet material.

[0022] S1.3. Add the fibers slowly in batches to the wet material to avoid clumping caused by concentrated feeding. Stir at low speed to ensure uniform dispersion of the fibers and obtain a high-ductility fiber-reinforced cementitious composite material.

[0023] As a preferred technical solution, in step S1.1, the low-speed stirring speed is 30-50 rpm, the time is 3-5 min, and the temperature is 15-25℃.

[0024] As a preferred technical solution, the medium-speed stirring speed in step S1.2 is 60-100 rpm, the time is 5-8 min, and the temperature is 15-25℃.

[0025] As a preferred technical solution, in step S1.3, the fibers are slowly sprinkled into the wet material in 2-3 batches, the stirring speed is 30-50 rpm, the time is 3-5 min, and the temperature is 15-25℃.

[0026] As a preferred technical solution, the mixer is a planetary mixer or a forced mixer to avoid fiber damage.

[0027] The high-ductility fiber-reinforced cementitious composite material is a type of fiber-reinforced cementitious composite material that exhibits high ductility under tensile and shear loads through systematic design. It has excellent ductility and microcrack width control characteristics. The high-ductility fiber-reinforced cementitious composite material can still maintain a small crack width even under large strain. In addition, the elastic modulus of the high-ductility fiber-reinforced cementitious composite material is about 20-30 GPa, which is about 1 / 2 of that of high-strength concrete. Therefore, in the concrete tower sections produced by combining the high-ductility fiber-reinforced cementitious composite material of this invention, the filler, as a weak section, will bear the main shrinkage strain, and the large number of microcracks generated can ensure that the rest of the tower section is in a low stress state, thus ensuring the durability performance requirements of the concrete tower.

[0028] Furthermore, the circumferential ribs extend laterally through the filler and the tower plate.

[0029] Furthermore, the circumferential rib has a near-rectangular shape, with the short side of the near-rectangle pointing radially towards the tower plate and the long side pointing circumferentially towards the tower plate. The short side of the circumferential rib is laterally located inside the tower plate, and the long side laterally passes through the filler and the two ends of the tower plate on both sides of the circumferential joint. The circumferential shape facilitates construction and provides strong adhesion.

[0030] Furthermore, the circumferential ribs are provided with connecting ribs to form a grid. The connecting ribs include short connecting ribs and long connecting ribs. The long sides of the circumferential ribs are connected with short connecting ribs, and the short sides are connected with long connecting ribs. The direction of the short connecting ribs is the radial direction of the tower plate, and the direction of the long connecting ribs is the circumferential direction of the tower plate. The grid can be tied, which is convenient for construction. The short connecting ribs can also provide compressive strength.

[0031] As a preferred technical solution, the main material of the tower plate is high-strength concrete or ultra-high performance concrete (UHPC), wherein the high-strength concrete is grade C70, C80 or C90, and the ultra-high performance concrete is grade UC1, UC2 or UC3.

[0032] Furthermore, structural reinforcement bars are vertically installed inside the tower section at the non-circular joint positions.

[0033] Unlike other tower sections which use high-ductility fiber-reinforced cementitious composite materials as fillers, the remaining sections use ordinary high-strength concrete with built-in structural reinforcement to meet the tower's load-bearing capacity requirements.

[0034] As a preferred technical solution, the materials of the circumferential reinforcement, connecting reinforcement and structural reinforcement are all steel bars or glass fiber reinforced plastic bars (GFRP bars).

[0035] One of the technical solutions of the present invention is to provide a construction method for the aforementioned concrete tower shrinkage stress relief device, the method comprising the following steps:

[0036] S2.1. Tie circumferential reinforcement in the mold and pour in the filling material, cure and shape to obtain a prefabricated concrete tower shrinkage stress relief device.

[0037] S2.2. Bind the structural ribs of the tower plate body in the mold and reserve the position of the prefabricated filling material joint;

[0038] S2.3 Install a concrete tower shrinkage stress relief device at the joint of the precast filling material;

[0039] S2.4. Cast the main body of the tower section and cure it to shape.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The prefabricated high ductility fiber reinforced cement-based composite material joint of the present invention serves as the weak section of the tower segment. By utilizing the tensile properties of the high ductility fiber reinforced cement-based composite material, the shrinkage stress of the structure can be effectively released, preventing the tower segment from cracking. This can effectively reduce the cost of tower segments that must be made of full-section high ductility fiber reinforced cement-based composite material, while also reducing the amount of steel used. It can be prefabricated in the factory, reducing the workload of on-site construction, improving construction efficiency, and effectively ensuring the load-bearing capacity of the structure.

[0042] (2) The present invention connects the filler and the concrete tower pieces with circumferential ribs, which can effectively ensure the integrity and load-bearing capacity of the structure. Attached Figure Description

[0043] Figure 1 This is a three-dimensional structural schematic diagram of the concrete tower shrinkage stress relief device in an embodiment of the present invention;

[0044] Figure 2 This is a perspective structural schematic diagram of the concrete tower shrinkage stress relief device in an embodiment of the present invention;

[0045] Figure 3 This is a three-dimensional assembly diagram of the concrete tower shrinkage stress relief device and the tower plate in an embodiment of the present invention;

[0046] Figure 4 This is a perspective assembly diagram of the concrete tower shrinkage stress relief device and the tower plate in an embodiment of the present invention;

[0047] Figure 5 The tensile stress-strain curve and crack width development diagram of the filler in the embodiments of the present invention are shown.

[0048] Explanation of markings in the diagram:

[0049] 1—filler, 2—circumferential ribs, 3—tower plate. Detailed Implementation

[0050] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0051] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, 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 invention. Furthermore, the terms "first," "second," "third," etc., used to describe a common object only indicate different instances of the same object, and do not imply that the objects described in this way must be in a given order, whether temporally, spatially, sequentially, or in any other way.

[0052] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0053] Example:

[0054] A concrete tower shrinkage stress relief device is applied to the integral concrete tower sections of prefabricated wind turbine towers, such as... Figures 1 to 4 As shown, the tower plate 3 includes a filler 1 and a circumferential rib 2. The filler 1 is provided at the circumferential joint of the tower plate 3. The material of the filler 1 is a high ductility fiber reinforced cementitious composite (engineering cementitious composite, ECC). The filler 1 and the tower plate 3 are connected by the internal circumferential rib 2. The filler 1 with the circumferential rib 2 is poured first to obtain the device, and the tower plate 3 is poured after the device is installed.

[0055] The combination of filler 1 and circumferential reinforcement 2 serves as a prefabricated component for stress relief. Circumferential reinforcement 2 acts as a structural reinforcement for the joint of prefabricated filler 1 and an lap reinforcement for bonding with the main body of tower plate 3. This design aims to improve the defects of unavoidable concrete shrinkage cracking during the production of prefabricated integral tower plate 3. It not only ensures the overall performance of concrete tower plate 3 and meets the structural bearing capacity requirements, but also effectively releases the shrinkage stress during the production of tower plate 3 due to the low elastic modulus of the high ductility fiber-reinforced cement-based composite material and the fact that cracking does not affect durability.

[0056] Tower plate 3 is an integral tower plate. The integral tower plate has a gap reserved at the circumferential joint position, and the gap is filled with filler 1.

[0057] During the hardening process, concrete shrinks in volume due to moisture evaporation (drying shrinkage) and cement hydration reaction (chemical shrinkage). Even under ideal curing conditions, moisture loss can still cause irreversible shrinkage deformation. Monolithic towers are usually large-volume structures, and the heat of hydration inside is difficult to dissipate quickly after pouring, resulting in a temperature difference between the inside and outside. The tensile stress caused by the temperature gradient during cooling will exacerbate shrinkage cracks. During the production of monolithic concrete towers, creep shrinkage of concrete is inevitable. Therefore, the high ductility fiber-reinforced cementitious composite material in this embodiment is needed to release shrinkage stress.

[0058] The curvature of the circumferential joint position accounts for 2-5% of the total tower plate 3. If it is too small, it will be inconvenient for construction and stress release; if it is too large, it will be uneconomical. In this embodiment, it is preferably 4%.

[0059] The high-ductility fiber-reinforced cementitious composite material comprises a solid component and a liquid component. The liquid component is water, and the water-cement ratio of the liquid component to the solid component is 0.6-0.8, preferably 0.68 in this embodiment. The solid component comprises the following components in parts by weight:

[0060] The ingredients are 100 parts cement, 50-100 parts mineral admixtures, 50-70 parts fine aggregate, 1-10 parts fiber, and 1-3 parts water-reducing agent. In this embodiment, the preferred ingredients are 100 parts cement, 75.2 parts mineral admixtures, 60 parts fine aggregate, 4 parts fiber, and 1.3 parts water-reducing agent.

[0061] Cement is a cementitious material that forms cement stone through hydration reaction, binding other components together and providing initial strength and basic bonding properties. During the hydration process, cement particles react chemically with water to produce various hydration products, which fill the internal pores of the material, gradually harden and enhance the overall structure of the material, which is the basis for the material to obtain strength. In this embodiment, P·O 52.5 ordinary Portland cement from China Resources Cement is preferred.

[0062] Common mineral admixtures include fly ash, silica fume, and slag powder. Fly ash particles are fine and can fill the gaps between cement particles, increasing the density of the material, improving workability, and can also undergo secondary reactions with cement hydration products to improve the later strength of the material. Silica fume has extremely high pozzolanic activity and can quickly react with calcium hydroxide produced by cement hydration to generate more gel substances, significantly improving the early and later strength of the material, while enhancing the durability and impermeability of the material. Slag powder undergoes a hydration reaction under the alkaline activation of cement hydration products, increasing the amount of hydration products and improving the later strength of the material. In this embodiment, fly ash is preferred.

[0063] Coarse aggregates are used less frequently in high-ductility fiber-reinforced cementitious composites. Fine aggregates with smaller particle sizes are mainly used, which mainly play a role in reducing shrinkage and improving wear resistance. Commonly used fine aggregates include iron ore fine aggregates, quartz sand, river sand, and manufactured sand. In this embodiment, quartz sand is preferred. Quartz sand can fill the voids between cement pastes, reduce the porosity inside the material, improve the density of the material, and enhance the volume stability of the material, which has an important impact on the strength and durability of the composite material.

[0064] The fibers are uniformly dispersed in the cement matrix, which can effectively prevent the generation and development of microcracks. When the material is subjected to external force, the fibers can bear part of the load, play a role in strengthening and toughening, and give the material high ductility. Commonly used fibers include polyvinyl alcohol (PVA) fibers, polypropylene (PP) fibers, steel fibers, etc. In this embodiment, polyvinyl alcohol fibers are preferred. Polyvinyl alcohol fibers have good bonding performance with the cement matrix. When the material is under tension, they can effectively inhibit the propagation of cracks and improve the tensile strain capacity and toughness of the material.

[0065] Water-reducing agents are essential for reducing the amount of mixing water and improving the fluidity of the material. In this embodiment, Subote's water-reducing agent is preferred. -Series I polycarboxylate high-performance water-reducing agents;

[0066] The specific steps for preparing high-ductility fiber-reinforced cementitious composite materials are as follows:

[0067] S1.1 Add cement, mineral admixtures and fine aggregates to a mixer and mix at a low speed of 40 rpm for 4 minutes at 20°C to ensure uniformity and no lumps, and obtain dry material;

[0068] S1.2 Slowly add water-reducing agent and water to dry material and mix. Stir at 80 rpm for 6 minutes at 20°C to form a uniform slurry and obtain wet material.

[0069] S1.3. Slowly sprinkle the fibers into the wet material in 2-3 batches to avoid clumping caused by concentrated feeding. Stir at 40 rpm at 20°C for 4 minutes to ensure uniform fiber dispersion and obtain a high ductility fiber-reinforced cementitious composite material.

[0070] The mixer can be a planetary mixer or a forced mixer to avoid fiber damage. In this embodiment, a planetary mixer is preferred.

[0071] like Figure 5 As shown, the high-ductility fiber-reinforced cementitious composite material is a type of fiber-reinforced cementitious composite material that exhibits high ductility under tensile and shear loads through systematic design. It has excellent ductility and microcrack width control characteristics. The high-ductility fiber-reinforced cementitious composite material can still maintain a small crack width even under large strain. In addition, the elastic modulus of the high-ductility fiber-reinforced cementitious composite material is about 20-30 GPa, which is about 1 / 2 of that of high-strength concrete. Therefore, in the concrete tower plate 3 produced by the high-ductility fiber-reinforced cementitious composite material in this embodiment, the filler 1, as a weak section, will bear the main shrinkage strain. The large number of microcracks generated can ensure that the rest of the tower plate 3 is in a small stress state, thus ensuring the durability performance requirements of the concrete tower.

[0072] The circumferential reinforcement 2 passes laterally through the filler 1 and the tower plate 3;

[0073] The circumferential reinforcement 2 is a near-rectangular shape. The direction of the short side of the near-rectangular shape is the radial direction of the tower plate 3, and the direction of the long side is the circumferential direction of the tower plate 3. The short side of the circumferential reinforcement 2 is located inside the tower plate 3, and the long side passes through the filler 1 and the two ends of the tower plate 3 on both sides of the circumferential joint. The circumferential shape is easy to construct and has strong adhesion.

[0074] The circumferential reinforcement 2 is provided with connecting reinforcements to form a grid. The connecting reinforcements include short connecting reinforcements and long connecting reinforcements. The long sides of the circumferential reinforcement 2 are connected with short connecting reinforcements, and the short sides are connected with long connecting reinforcements. The direction of the short connecting reinforcements is the radial direction of the tower plate 3, and the direction of the long connecting reinforcements is the circumferential direction of the tower plate 3. The grid can be tied, which is convenient for construction. The short connecting reinforcements can also provide compressive strength.

[0075] The main material of the tower plate 3 is high-strength concrete or ultra-high performance concrete (UHPC). The grade of high-strength concrete is C70, C80 or C90, and the grade of ultra-high performance concrete is UC1, UC2 or UC3. In this embodiment, C80 high-strength concrete is preferred.

[0076] Structural reinforcement bars are vertically installed inside the tower section 3 at the non-circular joint positions;

[0077] Unlike other materials that use high-ductility fiber-reinforced cementitious composite materials as filler, the remaining parts of tower section 3 are reinforced with ordinary high-strength concrete to meet the load-bearing capacity requirements of the tower.

[0078] The materials for the circumferential reinforcement 2, connecting reinforcement and structural reinforcement are all steel bars or glass fiber reinforced plastic bars (GFRP bars), and steel bars are preferred in this embodiment.

[0079] The specific steps for constructing the above-mentioned concrete tower shrinkage stress relief device are as follows:

[0080] S2.1. Tie the circumferential reinforcement 2 in the mold and pour the filler 1, cure and shape to obtain a concrete tower shrinkage stress relief device for the precast filler 1 joint.

[0081] S2.2. Bind the structural ribs of the main body of the tower plate 3 in the mold, and reserve the joint position of the prefabricated filler 1;

[0082] S2.3 Install a concrete tower shrinkage stress relief device at the joint of the precast filler 1;

[0083] S2.4, Cast the main body of the tower plate 3 and cure it.

[0084] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A concrete tower section shrinkage stress relief device, characterized by, The device includes a filler (1) and a circumferential rib (2). The tower plate (3) is provided with a filler (1) at the circumferential joint. The filler (1) is made of a high ductility fiber-reinforced cement-based composite material. The filler (1) and the tower plate (3) are connected by the internal circumferential rib (2). The device is obtained by first casting the filler (1) that is tied to the circumferential rib (2), and then casting the tower plate (3) after installing the device. The filler (1) and the circumferential reinforcement (2) are combined as prefabricated components for stress relief. The circumferential reinforcement (2) serves as the structural reinforcement of the joint of the prefabricated filler (1) and the lap reinforcement bonded to the main body of the tower plate (3). It aims to improve the defects of concrete shrinkage cracking that are unavoidable in the production process of prefabricated integral tower plate (3). It can not only ensure the overall performance of the concrete tower plate (3) and meet the structural bearing capacity requirements, but also effectively release the shrinkage stress in the production process of the tower plate (3) due to the low elastic modulus of the high ductility fiber reinforced cement-based composite material and the fact that cracking does not affect durability. The tower plate (3) adopts an integral tower plate, and the integral tower plate has a gap reserved at the circumferential joint position, and the gap is filled with filler (1). During the hardening process, concrete shrinks in volume due to moisture evaporation and drying shrinkage and chemical shrinkage caused by cement hydration reaction. Even under ideal curing conditions, moisture loss can still cause irreversible shrinkage deformation. Integral towers are usually large-volume structures, and the heat of hydration inside is difficult to dissipate quickly after pouring, resulting in a temperature difference between the inside and outside. The tensile stress caused by the temperature gradient during the cooling process will exacerbate shrinkage cracks. During the production of monolithic concrete towers, the concrete inevitably creeps and shrinks, so high ductility fiber-reinforced cementitious composite materials are needed to release shrinkage stress. The high-ductility fiber-reinforced cementitious composite material comprises a solid component and a liquid component. The liquid component is water, and the water-cement ratio of the liquid component to the solid component is 0.6-0.

8. The solid component comprises the following components in parts by weight: 100 parts cement, 50-100 parts mineral admixtures, 50-70 parts fine aggregates, 1-10 parts fiber and 1-3 parts water-reducing agent; The high-ductility fiber-reinforced cement-based composite material is a fiber-reinforced cement-based composite material that exhibits high ductility under tensile and shear loads through systematic design. It has excellent ductility and microcrack width control characteristics. The high-ductility fiber-reinforced cement-based composite material can still maintain a small crack width even under large strain. Therefore, in the concrete tower section (3) produced by combining the high-ductility fiber-reinforced cement-based composite material, the filler (1) will bear the main shrinkage strain as a weak section. The large number of microcracks generated can ensure that the other parts of the tower section (3) are in a small stress state, thus ensuring the durability performance requirements of the concrete tower. The circumferential rib (2) passes laterally through the filler (1) and the tower plate (3); The prefabricated high-ductility fiber-reinforced cement-based composite material joint serves as the weak section of the tower segment. By utilizing the tensile properties of the high-ductility fiber-reinforced cement-based composite material, the shrinkage stress of the structure can be effectively released, preventing the tower segment (3) from cracking.

2. The concrete tower shrinkage stress relief device according to claim 1, characterized in that, The curvature of the circumferential joint position accounts for 2-5% of the total curvature of the tower plate (3).

3. The concrete tower shrinkage stress relief device according to claim 1, characterized in that, The preparation method of the high ductility fiber-reinforced cementitious composite material includes the following steps: S1.1 Mix cement, mineral admixtures and fine aggregates, stir to obtain dry material; S1.2 Add the water-reducing agent and water to the dry material, mix and stir to obtain the wet material; S1.3 Add the fibers to the wet material in batches and mix them to obtain a high-ductility fiber-reinforced cementitious composite material.

4. The concrete tower shrinkage stress relief device according to claim 1, characterized in that, The circumferential rib (2) has a near-rectangular shape. The direction of the short side of the near-rectangular rib is the radial direction of the tower plate (3), and the direction of the long side is the circumferential direction of the tower plate (3). The short side of the circumferential rib (2) is located inside the tower plate (3) laterally, and the long side passes through the filler (1) and both ends of the tower plate (3) on both sides of the circumferential joint position.

5. A concrete tower shrinkage stress relief device according to claim 4, characterized in that, The circumferential rib (2) is provided with connecting ribs to form a grid. The connecting ribs include short connecting ribs and long connecting ribs. The long sides of the circumferential rib (2) are connected with short connecting ribs, and the short sides are connected with long connecting ribs. The direction of the short connecting ribs is the radial direction of the tower plate (3), and the direction of the long connecting ribs is the circumferential direction of the tower plate (3).

6. A concrete tower shrinkage stress relief device according to claim 1, characterized in that, The tower section (3) has vertical structural reinforcement bars installed at the non-circular joint position.

7. A construction method for a concrete tower shrinkage stress relief device as described in any one of claims 1 to 6, characterized in that, The method includes the following steps: S2.1, Tie the circumferential reinforcement (2) and pour the filling material (1), cure and shape to obtain the concrete tower shrinkage stress release device; S2.2, Tie the structural reinforcement of the main body of the tower plate (3) and reserve the joint position of the precast filling material (1); S2.3 Install a concrete tower shrinkage stress relief device at the joint of the precast filling material (1); S2.4, Cast the main body of the tower plate (3) and cure it.

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