Construction method for protecting steel member during staged implementation of structural column

Abstract

The invention relates to the technical field of structural engineering construction, in particular to a construction method for protecting a steel member during staged implementation of a structural column, which comprises the following steps of: sleeving the periphery of the steel member with a protective sleeve; plastic plate inner formworks are erected on the inner side and the outer side of the protective sleeve, and the steel member is enclosed by the plastic plate inner formworks; pouring formworks are erected on the inner side and the outer side of the plastic plate, and certain distances are reserved between the formworks located on the inner side and the plastic plate and between the formworks located on the outer side and the plastic plate to form pouring spaces; and concrete materials easy to detach are poured into the pouring space to form the hollow-structure column head. The method has the advantages that concrete pouring in the middle area of the component and binding and dismantling of reinforcing steel bars for temporary fixing are reduced, so that the waste project amount is reduced, the project cost is saved, the construction period is shortened, a new thought is provided for effective protection of reserved long-term development reinforcing steel bars in the recent project implementation stage, the types of reserved reinforcing steel bar protection methods in projects are enriched, and the construction period is shortened. And a green construction concept is practiced.

Description

Technical Field

[0001] The invention relates to the technical field of structural engineering construction, and in particular to a steel component protection construction method when a structural column is implemented in stages. Background Art

[0002] The implementation process of the vehicle base roof comprehensive property development project is generally as follows: the roof platform construction is completed simultaneously with the rail transit construction, and the completed platform land enters the market through the land transfer procedure, and the secondary development unit conducts comprehensive property development. As a result, there is a discontinuous construction condition of the roof and the underground construction projects. Since the development is a special and systematic project, it is affected by many external factors and the development time is uncertain.

[0003] In order to reserve greater flexibility for the development plan of the cover, usually only one-layer platform is constructed during rail transit construction, and the second-layer platform is implemented together with the cover property. The vertical components reserved for the cover platform are mostly conversion components or bear various loads such as cover soil, landscape, etc., with large cross-sections and much reinforcement.

[0004] In the process of promoting such projects, when the on-site construction cannot be completed vertically continuously due to phased development or batch implementation, the steel bars of concrete columns or steel-concrete columns need to be extended according to the force and structure. In the case of phased construction with a large number of reserved components, large cross-sections of individual components and a lot of reinforcement, the short-term protection of the reserved steel bars or steel sections must not only ensure that they are not corroded, but also consider the convenience of long-term construction.

[0005] At present, the commonly used engineering practice is to cast low-grade concrete over the entire section. This practice is indeed helpful in preventing steel bars from rusting during the construction window period, but it requires a lot of concrete and structural distribution reinforcement to be removed during secondary development. The reserved longitudinal force-bearing steel bars are often damaged due to the removal of supporting concrete and are difficult to repair.

[0006] In addition, previous studies on steel protection have focused on reducing steel corrosion to improve the durability of new or existing concrete structures, usually using coating, sealing and film covering protection methods, patch repair methods, electrochemical chloride extraction methods, cathodic protection methods, rust inhibitor methods, etc. All of the above methods passivate the steel surface or change the medium environment at the contact surface of steel and concrete through chemical reactions, delay steel corrosion, and thus improve the life of concrete structures. Each method has its applicability and corresponding impact. For example, epoxy coatings are porous and hydrophilic, and are easily worn during construction, and cannot obtain long-term anti-corrosion properties. Thicker coatings will also reduce the bond strength between steel and concrete, causing wider cracks in the components and exacerbating steel corrosion. Cathodic protection methods are mostly used under industrial water or seawater conditions. The design of the impressed current protection system inside the concrete structure is very complex, and there is a high risk of failure during the entire construction and use process. Rust inhibitors, whether they are incorporated for new construction or infiltrated for repair of existing projects, have a certain impact on concrete strength and the surrounding environment.

[0007] For short-term exposure of steel bars due to short-term shutdown or large-scale concrete pouring, the protection methods include simply spraying C15 strength mortar on the steel bars, or wrapping special moisture-proof plastic film around the steel bars in a dry environment, wrapping the film tightly with plastic tape, and then covering it with a sleeve.

[0008] In summary, the protection of steel bars in permanent structures is mainly to improve the durability of concrete structures; steel bar covering films and sleeves are temporary protection methods for steel bars that are exposed to the outside for very short periods of time. Their applicability to structural columns of projects that need to be developed in phases, where the reserved steel bars may be exposed to the outside for a long period of time, needs to be improved and verified. Summary of the invention

[0009] The purpose of the present invention is to provide a steel component protection construction method when the structural column is implemented in stages based on the above-mentioned deficiencies in the prior art, in which low-grade concrete or foam concrete is poured only on the surrounding steel bars and formwork devices with different moduli and steel bar protection devices that are conducive to the removal of concrete are used, thereby reducing the concrete pouring in the middle area of ​​the component, the temporary fixing steel bar tying and removal work, thereby reducing the amount of abandoned projects, saving project costs, and saving construction time.

[0010] The purpose of the present invention is achieved by the following technical solutions: A construction method for protecting steel components when a structural column is implemented in stages, which is used to protect steel components reserved in a future structural column, wherein the steel components extend out of the top surface of the future structural column being cast this time, and is characterized in that the construction method comprises the following steps: Provide protective sleeves around the outer periphery of the steel structure; Setting up plastic plate inner formwork on the inner and outer sides of the protective cover, wherein the plastic plate inner formwork encloses the steel member; A casting template is supported on the inner and outer sides of the plastic plate, and a certain distance is left between the templates on the inner and outer sides and the plastic plate to form a casting space; Concrete material that is easily removable is poured in the pouring space to form a hollow structural column head.

[0011] When the concrete material reaches the age and the casting formwork is removed, a rainproof protective cover is installed above the hollow structural column head formed by the concrete material.

[0012] Embedded bolts for connecting with the rainproof protective cover are embedded on the top of the concrete material, and the rainproof protective cover is installed on the hollow structure column head through the embedded bolts.

[0013] The casting template is assembled from an L-shaped template and a vertical bar template, wherein the L-shaped template serves as a corner template, and the corresponding L-shaped templates are connected by a vertical bar template serving as an intermediate template, so that several L-shaped templates and several vertical bar templates are connected to form a casting space for the hollow structure column head.

[0014] Short wooden braces are provided between the vertical formworks on opposite sides for top bracing and reinforcement.

[0015] The bottom of the plastic board inner formwork is buried in the future structural column to be cast.

[0016] During subsequent use, the hollow structure column head is chiseled out to the internal plastic plate formwork to separate the steel component from the hollow structure column head and the plastic plate formwork. After that, the protective cover wrapped around the reserved steel component is removed to expose the reserved steel component.

[0017] The advantages of the present invention are: 1) For structural members with large cross-sections and more reinforcement, this method of hollow protection reserved reinforcement can effectively isolate the air and prevent steel corrosion. Compared with pouring concrete in the entire cross-section, it greatly saves the amount of concrete pouring and demolition work, as well as the distribution reinforcement for temporary fixing of longitudinal reinforcement; 2) The longitudinal reinforcement is wrapped in foam sleeves and isolated by "J"-shaped plastic plates, which prevents damage to it when the concrete is broken. At the same time, the outer circle of the longitudinal reinforcement is wrapped in concrete, which can effectively block the corrosion of external air and water vapor, thereby improving the safety and effectiveness of the reserved longitudinal reinforcement; 3) When the protective layer concrete is broken, due to the effect of the "J"-shaped plastic plate, it is only necessary to chisel shallow holes along the inner and outer circles at the bottom of the protective layer to remove it as a whole. The whole piece can be hoisted and removed, which greatly improves efficiency; 4) When pouring the protective layer concrete, you can consider marking the removal needs, such as marking the height of the bottom end of the "J"-shaped plastic plate to facilitate identification of the bottom chiseling position, thereby minimizing chiseling; selecting a number of longitudinal reinforcement horizontal spacing marks to facilitate the vertical cutting of the longitudinal reinforcement protective layer concrete into small pieces; marking the end position of the longitudinal reinforcement top to facilitate the horizontal cutting of the longitudinal reinforcement protective layer concrete, etc. 5) For steel-concrete columns, the protection scheme for the outer circle of longitudinal reinforcement is the same as above; at the same time, by pouring permanent concrete inside the steel, the anti-corrosion coating area of ​​the steel and the long-term corrosion removal project are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of the first embodiment provided by the present invention; Figure 2 Two cross-sectional schematic diagrams of the first embodiment of the present invention; Figure 3 This is a schematic structural diagram of a template device for a hollow structure column head according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the first embodiment of the present invention when it is dismantled; Figure 5 This is a schematic diagram of the structure of the second embodiment provided by the present invention; Figure 6 It is a cross-sectional schematic diagram of the second embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of a template device for a hollow structure column head according to the second embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of the second embodiment of the present invention when it is dismantled. DETAILED DESCRIPTION

[0019] The features of the present invention and other related features are further described in detail below through embodiments in conjunction with the accompanying drawings to facilitate understanding by those skilled in the art: like Figure 1-8 As shown, the numbers 1-17 in the figure respectively represent: the long-term structural column 1 of this casting, permanent stirrups 2, reserved longitudinal reinforcement 3, reserved longitudinal reinforcement 4, polyethylene foam steel bar protective cover 5, plastic board inner formwork 6, L-shaped formwork 7, vertical bar formwork 8, short wooden support 9, low-grade concrete or foam concrete 10, rainproof protective cover 11, steel section 12, reserved permanent steel bars 13, permanent concrete 14, flange inter-formwork 15, embedded bolts 16, and cutting position of temporary concrete protection layer 17.

[0020] Embodiment 1: Figures 1 to 4 As shown, in this embodiment, the steel member protection structure is applied to the short-term protection of the steel bars of the reinforced concrete frame column when the structural column is implemented in stages. The specific implementation method is as follows: A certain height h1 of the future structural column 1 to be cast is implemented above the recently implemented structural surface elevation. The height of the future structural column 1 to be cast is in accordance with the specifications and atlas requirements. The column section, stirrups, concrete grade and structural requirements in this height range are the same as those of the permanent structural column to be implemented in the future. It is recommended that the protective layer of the distributed reinforcement at the height h1 section of the future structural column 1 to be cast be set to be greater than 50mm.

[0021] The reserved longitudinal reinforcements are staggered and cut off at a certain height h2 above the height of the future structural column 1. The first batch of steel bars are cut off at about 200mm above h1 as the reserved longitudinal reinforcement 3 (joint area percentage ≤ 50%), which is convenient for the future mechanical connection construction of steel bars; the second batch of steel bars are cut off at about 200mm below h2 as the reserved longitudinal reinforcement 4.

[0022] Within the height range of h2, the longitudinal reinforcements (reserved longitudinal reinforcements 3 and 4) distributed around are wrapped with polyethylene foam steel bar protective sleeves 5 for the first layer of protection of the longitudinal reinforcements. The thickness of the polyethylene foam steel bar protective sleeves 5 is preferably 10-20 mm. Plastic board inner templates 6 are set up on both sides of the polyethylene foam steel bar protective sleeves 5. Figure 2 As shown, the plastic board inner formwork 6 is entirely enclosed around the periphery of each longitudinal reinforcement to form a second layer of protection. When in use, the plastic board inner formwork 6 also serves as a formwork for subsequent concrete hollow structure column heads. The thickness of the plastic board inner formwork 6 is preferably 20-30 mm.

[0023] In this embodiment, in order to facilitate fixation, the longitudinal section structure of the plastic plate inner formwork 6 is set to be a "J" shape, that is, the plastic plate inner formwork 6 has a toe-shaped structure extending outward, and the toe-shaped structure is embedded in the upper side of the h1 segment distribution reinforcement of the future structural column 1 cast this time, and then the h1 segment concrete is cast, so that the plastic plate inner formwork 6 and the future structural column 1 cast this time form an integral structure to achieve self-stabilization. The height of the "J"-shaped plastic plate inner formwork 6 is 200-220mm lower than the height of h2, so as to just cover the reserved longitudinal reinforcement 3. If necessary, a transverse tie can be set between the waists of the plastic plate inner formwork 6 on both sides to further improve its stability.

[0024] Within the height range h2, the thickness of the protective layer on both sides of the reserved longitudinal reinforcement 3 and the reserved longitudinal reinforcement 4 shall not be less than the thickness of the permanent structure protective layer starting from the outer side of the plastic board inner formwork 6.

[0025] Within the height range of h2, the templates are supported on the inner and outer sides of the reserved longitudinal reinforcement 3 and the reserved longitudinal reinforcement 4. The structure of the template is as follows Figure 3 shown.

[0026] like Figure 3As shown in the left figure, for a rectangular column, the outer template of the longitudinal reinforcement consists of four corner templates plus several middle templates. Among them, the four corner templates are L-shaped templates 7, and their leg length is preferably 500-1000mm; the middle template is a vertical bar template 8, and its width is preferably 300-500mm. L-shaped templates 7 and vertical bar templates 8 of different sizes are combined to form an outer template that meets the column section. The inner template is also composed of four corner templates plus several middle vertical bar templates, and the size of the enclosed structure meets the requirements of forming a hollow structural column head.

[0027] like Figure 3 As shown in the right figure, for a circular cross-section column, a plurality of vertical strip templates 8 can be fitted to form an inner and outer layer template. In some cases, a steel template can also be used.

[0028] In this embodiment, the outer template adopts a conventional fixing scheme, and the inner template can be reinforced by arranging a cross short wooden support 9 inside. If necessary, the plastic board inner template 6 can be further fixed with a short support between it and the template.

[0029] Low-grade concrete or foam concrete 10 or other easily removable casting materials are poured between the inner and outer layer formworks and the plastic board inner formwork 6. After the low-grade concrete or foam concrete 10 is dense and reaches the age, the formwork is removed, and hollow structural capitals are formed on the inner and outer sides of the plastic board inner formwork 6 to provide three-layer protection for the reserved longitudinal reinforcement.

[0030] When the hollow structure column head reaches the age, the L-shaped formwork 7 and the vertical strip formwork 8 are removed.

[0031] A rainproof protective cover 11 made of plastic or aluminum is set at the top of the hollow structural column to prevent rainwater from entering the column. During construction, bolts are embedded in the protective layer at the top of the longitudinal reinforcement at a certain distance to facilitate the fixing and installation of the rainproof protective cover 11 by bolts.

[0032] like Figure 4 As shown, during the secondary development, the reserved longitudinal reinforcements are separated from the protective layer concrete and the plastic board inner formwork 6 by chiseling a notch along the inner and outer protective layers of the reserved longitudinal reinforcements around the cutting position 17 to the inner plastic board inner formwork 6. After that, the polyethylene foam protective cover wrapped around the reserved longitudinal reinforcements is peeled off to expose the reserved longitudinal reinforcements 3 and 4.

[0033] If the concrete block of the longitudinal reinforcement protection layer is not easy to transport, it can be cut horizontally in the range of the longitudinal reinforcement top protection layer and divided into 3 small blocks for transportation, or it can be cut vertically to avoid the longitudinal reinforcement position and divided into strips. In order to facilitate accurate avoidance of steel bars when chiseling or cutting, it can be marked when pouring low-grade concrete or foam concrete 10.

[0034] The exposed reserved longitudinal reinforcement is connected and extended, and stirrups, tie reinforcement and concrete pouring are carried out according to the requirements of permanent structure.

[0035] Embodiment 2: This embodiment is different from Embodiment 1 in that: Figures 4 to 8 As shown, this embodiment is applied to the short-term protection of steel and steel bars of steel concrete frame columns. The main differences of its specific implementation method compared with the first embodiment are as follows: Within the reserved height range of the steel 12, the flange of the steel 12 is reinforced according to the concrete grade and construction requirements of the permanent structure, and whether to set the reserved permanent stirrups 13 in the steel is determined according to the configuration of the column stirrups; the outer side of the flange of the steel 12 is treated with anti-corrosion. After that, the permanent concrete 14 is poured inside the steel 12.

[0036] In this embodiment, the permanent concrete 14 is poured by arranging an inter-flange formwork 15 between the steel sections 12 to enclose a pouring space for the permanent concrete 14 .

[0037] During demolition, the anti-corrosion protective layer on the outside of the flange of steel section 12 is removed; longitudinal reinforcement is extended according to the permanent structure, steel sections and studs are welded, stirrups are installed, and concrete is poured.

[0038] Although the above embodiments have described in detail the concepts and embodiments of the present invention with reference to the accompanying drawings, ordinary technicians in this field can recognize that various improvements and changes can still be made to the present invention without departing from the scope of the claims, so they are not described one by one here.

Claims

1. A method for protecting steel components during phased construction of structural columns, which is used to protect steel components reserved in future structural columns, wherein the steel components extend out of the top surface of the future structural columns being cast this time, and is characterized in that: The construction method comprises the following steps: Provide protective sleeves around the outer periphery of the steel structure; Setting up plastic plate inner formwork on the inner and outer sides of the protective cover, wherein the plastic plate inner formwork encloses the steel member; A casting template is supported on the inner and outer sides of the plastic plate, and a certain distance is left between the templates on the inner and outer sides and the plastic plate to form a casting space; Concrete material that is easily removable is poured in the pouring space to form a hollow structural column head.

2. The method for protecting steel components during phased construction of structural columns according to claim 1, characterized in that: When the concrete material reaches the age and the casting formwork is removed, a rainproof protective cover is installed above the hollow structural column head formed by the concrete material.

3. The method for protecting steel components during phased construction of structural columns according to claim 1, characterized in that: Embedded bolts for connecting with the rainproof protective cover are embedded on the top of the concrete material, and the rainproof protective cover is installed on the hollow structure column head through the embedded bolts.

4. The method for protecting steel components during phased construction of structural columns according to claim 1 is characterized in that: The casting template is assembled from an L-shaped template and a vertical bar template, wherein the L-shaped template serves as a corner template, and the corresponding L-shaped templates are connected by a vertical bar template serving as an intermediate template, so that several L-shaped templates and several vertical bar templates are connected to form a casting space for the hollow structure column head.

5. The method for protecting steel components during phased construction of structural columns according to claim 4 is characterized in that: Short wooden braces are provided between the vertical formworks on opposite sides for top bracing and reinforcement.

6. The method for protecting steel components during phased construction of structural columns according to claim 1, characterized in that: The bottom of the plastic board inner formwork is buried in the future structural column to be cast.

7. The method for protecting steel components during phased construction of structural columns according to claim 1 is characterized by: During subsequent use, the hollow structure column head is chiseled out to the internal plastic plate formwork to separate the steel component from the hollow structure column head and the plastic plate formwork. After that, the protective cover wrapped around the reserved steel component is removed to expose the reserved steel component.

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