Connecting structure of concrete enclosing purlin and glass fiber reinforced plastic bar enclosure and construction method

Abstract

The invention discloses a connecting structure of a concrete enclosing purlin and a glass fiber rib enclosure and a construction method, and belongs to the technical field of foundation pit supporting. The connecting structure comprises an enclosure structure, and glass fiber ribs are arranged in the enclosure structure; the enclosing structure is fixedly connected with the concrete enclosing purlin through the triangular bracket and the hanging bar; the triangular brackets are evenly distributed above the concrete enclosing purlin in the length direction, each triangular bracket comprises an upper side edge, a lower side edge and a bevel edge which are fixedly connected, and the two side edges are perpendicular to each other. The upper side edge is fixed on the enclosure structure through a plurality of expansion bolts, the lower side edge is welded with an upper reinforcing steel bar of the concrete enclosing purlin, the lower side edge is fixedly connected with the upper part of the hanging bar, and the lower part of the hanging bar extends into the concrete enclosing purlin and then is poured and fixed together with the concrete enclosing purlin. Anchor bars arranged in the enclosure are prevented from being anchored with the concrete enclosing purlins, and a cutter is prevented from being abraded when the shield tunneling machine breaks the enclosure structure; the problem that when a foundation pit enclosure structure adopts glass fiber ribs, hanging bars for fixing the concrete enclosing purlins cannot be welded to the glass fiber ribs, and consequently the concrete enclosing purlins cannot be fixed to the enclosure structure is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of foundation pit support, and in particular relates to a connection structure of a concrete purlin and a glass fiber reinforced enclosure and a construction method. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the development of economy, shield tunnels are developing in the direction of large cross-section, long distance and complex construction environment, and a number of urban municipal tunnels and underwater tunnels with super large cross-sections have been built. In the past, in the traditional practice, when the shield started and arrived at the working shaft, it was necessary to manually chisel out the enclosure structure inside the working shaft portal, which made the construction conditions difficult, time-consuming and costly, and would expose the soil in the end reinforcement area for a long time, posing a high construction risk.

[0004] In order to solve the above-mentioned technical problems, the existing technology replaces the ordinary steel bars in the retaining structure within the tunnel portal with glass fiber bars, so that when the shield machine starts and reaches the shield shaft, the general shield machine cutter head can be used to directly cut the retaining structure, so that the shield machine can directly enter and exit the tunnel, and the shield can directly cut concrete and steel, avoiding the later processing of the retaining structure.

[0005] At present, fiberglass reinforcement has been widely used in the retaining structure of subway station foundation pits, while the retaining structure of super-large diameter shield tunnel working shaft foundation pits is relatively less used. Compared with the situation where the retaining structure at the shield opening of the subway station foundation pit is mostly supported by steel, the super-large diameter shield tunnel working shaft foundation pit is deeper and will be equipped with multiple concrete supports + steel support combinations. It is inevitable that the retaining structure at the shield opening will use concrete supports.

[0006] In traditional practice, concrete purlins can be anchored to the retaining structure by setting hangers and anchor bars. For example, patent CN107574826A discloses a universal connection structure and connection construction method for concrete purlins and retaining structures, including hangers and a bracket at the lower part of the purlin, one end of the hanger is fixed to the main reinforcement of the retaining structure, and the other end is cast into the concrete purlin in a bent structure; the bracket includes a support plate supporting the bottom of the purlin and a support leg obliquely arranged between the support plate and the retaining structure, one end of the support leg is fixed to the bottom of the support plate, and the other end is fixedly connected to the main reinforcement of the retaining structure.

[0007] However, when the above approach is applied to the scenario of the foundation pit retaining structure of the super-large diameter shield tunnel working shaft, the following problems exist: 1) If anchor bars are set in the enclosure to anchor the concrete purlin, ordinary steel bars will affect the shield machine's ability to break through the enclosure structure, causing severe wear on the cutter; 2) When the foundation pit retaining structure uses glass fiber reinforcement, the hanger bars used to fix the concrete purlins cannot be welded to the glass fiber reinforcement of the retaining structure, resulting in the concrete purlins being unable to be fixed on the retaining structure; 3) Concrete purlins need to set up a ground formwork first to tie the steel bars and pour the concrete. It is not possible to directly set up a bracket to fix the purlin under the over-excavation of the purlin like a steel support. Summary of the invention

[0008] In view of the above problems, the present invention provides a connection structure and construction method of concrete purlin and glass fiber reinforced enclosure, which connects the concrete purlin with the enclosure structure by arranging a triangular bracket, hanging bars and expansion bolts above the concrete purlin, thereby avoiding the need to set anchor bars in the enclosure to anchor the concrete purlin, and preventing the shield machine from causing serious wear on the tool when breaking the enclosure structure; it solves the problem that when the foundation pit enclosure structure adopts glass fiber reinforced bars, the hanging bars used to fix the concrete purlin cannot be welded to the glass fiber reinforced bars of the enclosure structure, resulting in the concrete purlin being unable to be fixed on the enclosure structure; and there is no need to over-excavate and set a bracket under the purlin like a steel support.

[0009] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, a connection structure of a concrete purlin and a glass fiber reinforced enclosure is provided, comprising an enclosure structure, wherein the enclosure structure is made of glass fiber reinforced bars as a skeleton and poured with concrete; The enclosure structure is fixedly connected to the concrete enclosure purlin through triangular brackets and hanging rods; a plurality of triangular brackets are evenly arranged above the length direction of the concrete enclosure purlin, and the triangular brackets include an upper side, a lower side, and a beveled side that are fixedly connected, and the two side sides are perpendicular to each other; The upper side is fixed to the retaining structure by a number of expansion bolts, the lower side is welded to the upper steel bars of the concrete purlin, the lower side is fixedly connected to the upper part of the hanger, the lower part of the hanger extends into the concrete purlin, and then is cast and fixed together with the concrete purlin.

[0010] Preferably, the hanger bar is arranged at the centroid position of the concrete purlin; and a plurality of the expansion bolts are arranged at a set interval.

[0011] Preferably, the triangular bracket is formed by welding angle steels, the sides of the two sides are equal in length, the two ends of the hypotenuse are not connected to the ends of the sides, and a certain distance is reserved outside the positions where the two ends of the hypotenuse are connected to the two sides to ensure that there is sufficient installation space when installing the expansion bolts at the upper end of the upper side.

[0012] Preferably, the hanger bar is made of steel bars into a "U" shape, wherein the upper end of the hanger bar is bent in an arc and the lower end of the straight line is bent at 90°.

[0013] In a second aspect, a construction method of a connection structure of a concrete purlin and a glass fiber reinforced enclosure is provided, using the above-mentioned connection structure of a concrete purlin and a glass fiber reinforced enclosure, and the specific steps are as follows: S1. Determine the number of triangular brackets used in the concrete purlin per unit length and construction length, as well as the specifications of expansion bolts through calculation; and make triangular brackets and hanging bars; S2. Dig down along the foundation pit retaining structure until the bottom elevation of the concrete purlin. Roughen the joint between the concrete purlin and the retaining structure on the retaining structure. S3, support the formwork and tie the concrete purlin reinforcement, anchor the hanger into the steel mesh at the centroid of the concrete purlin, weld the lower side of the triangular bracket to the top side reinforcement of the concrete purlin, and fix the upper side to the enclosure structure through multiple expansion bolts; S4. Pour concrete purlins.

[0014] Preferably, in S1, firstly, the height and width of the concrete purlin are obtained, the specifications of the triangular bracket are determined, and the number of expansion bolts required to be set on the triangular bracket is calculated; Next, determine the deadweight of the concrete purlin within the unit length and the uniformly distributed construction load, and then obtain the total shear bearing capacity and total tensile bearing capacity of all expansion bolts within the unit length based on the force balance; Then find out the tensile and shear bearing capacities of the top row of expansion bolts; determine the specifications of the expansion bolts to be used; Calculate the number of triangular brackets based on the determined expansion bolt specifications.

[0015] Preferably, the number of expansion bolts required to be provided on the triangular bracket is calculated by the following formula: a=b / 2; a=L(n-1); Where: b: Concrete purlin width; a: The distance from the top expansion bolt to the bottom expansion bolt on the upper side; L: Expansion bolt spacing. According to construction experience, the spacing L is 300-400mm. n: The number of expansion bolts on a single triangular bracket.

[0016] Preferably, the total shear bearing capacity and total tensile bearing capacity of all expansion bolts on the concrete purlin within a unit length are calculated as follows: ; ; Where: F: vertical force in the force system of the connection structure within unit length; M: Bending moment of the connecting structure force system per unit length; N V : The total shear bearing capacity of all expansion bolts on the concrete purlin within unit length; N F : The total tensile bearing capacity of all expansion bolts on the concrete purlin within unit length; N 1 : Self-weight load of concrete purlin per unit length; q: Construction uniformly distributed load on the concrete purlin within unit length; h: height of concrete purlin.

[0017] Preferably, the calculation formulas for the tensile bearing capacity and the shear bearing capacity of the top row of expansion bolts are as follows: N V1 =N V2 =N V3 =…=N Vn =N V / n; N Fn-1 =-(N 1 b+qb 2 )L / {(h+a / 2)(a+L)}; Where: N V1 、N V2 、N V3 ,…N Vn : The shear bearing capacity of each row of expansion bolts from bottom to top within the unit length; N F1 、N F2 、N F3 ,…N Fn-1 : The tensile bearing capacity of each row of expansion bolts from bottom to top within unit length, except for the expansion bolts at the bottom.

[0018] Preferably, the expansion bolt specifications are determined by the following formula: N Vn / N Fn-1 =N Vn ' / N Fn-1 '; Where: N Fn-1 ': tensile bearing capacity of the top expansion bolt on a single triangular bracket; N Vn ': Shear bearing capacity of the top expansion bolt on a single triangular bracket; The number of the triangular brackets is determined by the following formula: N Vn =m N Vn '; Where: m: The number of triangular brackets on the concrete purlin per unit length.

[0019] Compared with the prior art, the present invention has the following advantages and positive effects: The present invention connects the concrete purlin with the retaining structure by arranging a triangular bracket, a hanging bar and an expansion bolt above the concrete purlin, thereby avoiding the need to arrange anchor bars in the retaining to anchor the concrete purlin, and preventing the shield machine from causing serious wear of the cutter when breaking the retaining structure; it solves the problem that when the foundation pit retaining structure adopts glass fiber bars, the hanging bars used to fix the concrete purlin cannot be welded to the glass fiber bars of the retaining structure, resulting in the concrete purlin being unable to be fixed on the retaining structure; and there is no need to over-excavate and arrange a bracket under the purlin like a steel support.

[0020] The present invention can obtain the data such as the height, width, deadweight and construction uniformly distributed load of the concrete purlin within the unit length and the construction length to obtain the specifications and quantity of the triangular bracket and the specifications of the expansion bolts used, which can not only ensure the actual supporting effect, but also prepare the required materials in advance before construction, thus saving construction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] Figure 1 is an overall schematic diagram of the connection structure of Embodiment 1 or Embodiment 2 of the present invention; Figure 2 is a schematic diagram of the enclosure structure of Example 1 or Example 2 of the present invention; Figure 3 is a schematic diagram of a triangular bracket according to Embodiment 1 or Embodiment 2 of the present invention; Figure 4 is a schematic diagram of a suspension rod according to Embodiment 1 or Embodiment 2 of the present invention; Figure 5 is a force balance analysis diagram of the entire force system of the connection structure of Example 2 of the present invention; Figure 6 is a horizontal force analysis diagram of an expansion bolt according to Embodiment 2 of the present invention; In the figure: 1. Enclosure structure; 2. Concrete purlin; 3. Triangular bracket; 4. Hanger; 5. Fiberglass reinforcement; 6. Angle steel; 7. Expansion bolt; 8. Weld. DETAILED DESCRIPTION

[0023] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0024] The present invention is described in detail below in conjunction with the accompanying drawings.

[0025] Example 1 This embodiment discloses a connection structure of a concrete purlin 2 and a glass fiber reinforcement 5 enclosure, such as Figure 1 As shown, it includes a retaining structure 1, which uses glass fiber reinforcement 5 as a skeleton and is then made of poured concrete; the retaining structure 1 is fixedly connected to the concrete purlin 2 through a triangular bracket 3 and a hanging reinforcement 4.

[0026] Specifically, Figure 1 As shown, a plurality of triangular brackets 3 are evenly distributed above the length direction of the concrete purlin 2, and the triangular bracket 3 includes an upper side, a lower side, and a hypotenuse, two side edges are perpendicular to each other, and the two side edges are fixedly connected to a hypotenuse by welding.

[0027] like Figure 2 As shown in FIG. 1 , the height range of the concrete purlin 2 is chiseled in advance on the enclosure structure 1. When the enclosure structure 1 is connected to the concrete purlin 2, as shown in FIG. Figure 1 , Figure 3 As shown, the upper side is fixed to the enclosure structure 1 by a plurality of expansion bolts 7, and the spacing between the expansion bolts 7 is consistent; specifically, an expansion bolt 7 is arranged close to the connection between the upper side and the lower side, and the remaining expansion bolts 7 are arranged at a certain spacing, and the uppermost expansion bolt 7 is arranged above the connection between the upper side and the hypotenuse, and close to the connection between the upper side and the hypotenuse. In this embodiment, the upper side is fixedly connected to the enclosure structure 1 by three expansion bolts 7. In this embodiment, three expansion bolts 7 are arranged on the upper side.

[0028] like Figure 1 As shown, the lower side is welded to the upper steel bars of the concrete purlin 2 to form a weld 8, and the lower side is fixedly connected to the upper part of the hanger 4, the lower part of the hanger 4 extends into the concrete purlin 2, and then is cast and fixed together with the concrete purlin 2. It should be noted that the hanger 4 should be set at the centroid position of the concrete purlin 2. The purpose is to put the dead weight of the concrete purlin 2 on the lower side of the triangular bracket 3, and the upper side of the triangular bracket 3 is fixedly connected to the enclosure structure 1 through the expansion bolts 7. The dead weight of the concrete purlin 2 eventually produces a vertical shear force on the expansion bolts 7. This part of the shear force is resisted by using expansion bolts 7 of a certain specification, and this part of the force is transmitted to the enclosure structure 1 at the same time. At the same time, the lower side of the triangular bracket 3 connected to the concrete purlin 2 will generate a bending moment under the action of the concrete purlin 2, and will eventually produce a lateral horizontal pulling force on the expansion bolt 7. The expansion bolt 7 implanted in the enclosure structure 1 can resist this part of the pulling force, and this part of the force is transmitted to the enclosure structure 1.

[0029] It is understandable that this requires the triangular bracket 3 to have strong rigidity for force transmission. Figure 3As shown, the triangular bracket 3 is welded by angle steel 6, wherein the lengths of the two sides are equal, the two ends of the hypotenuse are not connected to the ends of the sides, and a certain distance is reserved outside the positions where the two ends of the hypotenuse are connected to the two sides. In this embodiment, the reserved distance range is 100-150mm, which is used to ensure that there is enough installation space when installing the expansion bolts 7 at the upper end of the upper side. It should be noted that the hanger 4 is set at the position where the lower side is connected to the hypotenuse. The advantages of using angle steel 6 are that, first, angle steel 6 is more common in engineering; second, angle steel 6 is easy to process, and one side of angle steel 6 can be connected to the enclosure structure 1 or the concrete purlin 2, and the other side can provide support force, which can also be equivalent to the role of ribs. In this embodiment, angle steel 6 adopts the specification of L80×8, that is, the side width is 80mm and the side thickness is 8mm. It can be understood that angle steel 6 needs to have strong rigidity, and its specifications are set according to the actual force requirements. In some embodiments, angle steel 6 larger or smaller than L80×8 specifications can be adopted.

[0030] In this embodiment, if Figure 4 As shown, the hanger bar 4 is made of HRB400 steel bars into a "U" shape, wherein the upper end of the hanger bar 4 is bent in an arc with a radius of R, and the lower end straight section is bent 90°. It can be understood that the length of the lower end straight section needs to meet the anchoring length required by the specification, and R needs to be able to be hung on the angle steel 6. In this embodiment, the specification of the angle steel 6 is L80, so the value of R is 65mm. The diameter of the hanger bar 4 must meet the tensile bearing capacity requirements and will not cause damage on the basis. In this embodiment, steel bars with a diameter of 25mm or 28mm are used.

[0031] It can be understood that after the enclosure structure 1 and the concrete purlin 2 are connected through the triangular bracket 3, the hanger 4 and the expansion bolt 7, the concrete purlin 2 can strengthen the integrity of the enclosure structure 1 and transmit the horizontal force it is subjected to to the supporting member.

[0032] The connection structure of this embodiment can solve the problem that the hanging rod 4 used to fix the concrete purlin 2 cannot be welded with the glass fiber reinforcement 5 of the enclosure structure 1, and the expansion bolt 7 is used to improve the convenience and safety of construction, avoiding the traditional practice of removing the protective layer of the enclosure structure 1 and then welding the hanging rod 4 with the main reinforcement of the enclosure structure 1. On the other hand, it avoids setting anchor steel bars in the enclosure structure 1 to fix the concrete purlin 2, which will affect the shield machine to break the enclosure structure 1 and cause serious wear of the tool.

[0033] Example 2 The construction method of a connection structure of a concrete purlin 2 and a glass fiber reinforcement 5 disclosed in this embodiment uses a connection structure of a concrete purlin 2 and a glass fiber reinforcement 5 disclosed in Example 1, and the specific steps are as follows: S1. To ensure the stability of the connection between the concrete purlin 2 and the enclosure structure 1, the specifications and quantity of the triangular brackets 3 and the specifications of the expansion bolts 7 are calculated according to the deadweight of the concrete purlin 2, the uniformly distributed construction load, and the length, width, height and other data of the concrete purlin 2; It can be understood that multiple triangular brackets 3 are evenly distributed in the length direction of the concrete purlin 2, and the spacing of the triangular brackets 3 can be obtained by calculating the number of triangular brackets 3; wherein the construction uniformly distributed load is a standard value, which can be obtained from the "Code for Loads on Building Structures" GB50009-2012.

[0034] The specific calculation steps in S1 are as follows: First, the height and width of the concrete purlin 2 are obtained, the specifications of the triangular bracket 3 are determined, and the number of expansion bolts 7 required to be set on the triangular bracket 3 is calculated; Next, the deadweight of the concrete purlin 2 within the unit length and the uniformly distributed construction load are determined, and then the total shear bearing capacity and the total tensile bearing capacity of all the expansion bolts 7 within the unit length are obtained based on the force balance; Then, the tensile bearing capacity and shear bearing capacity of the top row of expansion bolts 7 are calculated; the specifications of the expansion bolts 7 to be used are determined; According to the determined specifications of the expansion bolts 7, the number of the triangular brackets 3 is calculated.

[0035] The specification of the triangular bracket 3 and the number of expansion bolts 7 required to be arranged on the triangular bracket 3 are calculated by the following formula (1) and formula (2): a=b / 2(1); a=L(n-1)(2); Where: b: width of concrete purlin 2; a: The distance from the top expansion bolt 7 to the bottom expansion bolt 7 on the upper side; L: the distance between the expansion bolts 7. According to construction experience, the distance L is 300-400 mm. In this embodiment, the value is 300 mm. n: the number of expansion bolts 7 on a single triangular bracket 3.

[0036] In Example 1, it is emphasized that the triangular bracket 3 adopts an isosceles triangle design. Similarly, it is necessary to ensure that the force-bearing lengths of the upper side and the lower side are consistent. Therefore, the distance between the expansion bolts 7 from the top to the bottom of the upper side is equal to the distance between the hanger 4 and the upper side, and formula (1) can be obtained.

[0037] Before installing the expansion bolts 7 to the enclosure structure 1, it is necessary to consider reserving installation holes for the expansion bolts 7 on the upper side. This requires considering the spacing L between the expansion bolts 7. This spacing L needs to meet the requirements of the specification and ensure the convenience of actual installation. According to construction experience, the general value of the spacing L is 300-400mm. In this embodiment, the value is 300mm. According to L and a, the number of expansion bolts 7 on the triangular bracket 3 can be calculated, that is, formula (2).

[0038] Before calculation, the overall force balance analysis of the connection structure force system is carried out, such as Figure 5 , Figure 6 As shown, before calculating the total shear bearing capacity and total tensile bearing capacity of all expansion bolts 7 within a unit length, it is assumed that the triangular bracket 3 is absolutely rigid and the expansion bolts 7 are elastic, so the bolt connection is designed according to elasticity; the neutral axis of all expansion bolts 7 is located at the centroid of the bottom row of expansion bolts 7, and the tensile force on each expansion bolt 7 is proportional to its distance from the neutral axis. Figure 5 , Figure 6 As shown, the self-weight load N of the concrete purlin 2 1 , under the action of uniform construction load q, in the overall force, the expansion bolt 7 mainly bears downward force and bending moment, so when calculating, consider the shear bearing capacity N of all expansion bolts 7 V And tensile bearing capacity N F ; like Figure 5 In the overall force balance analysis of the connection structure force system shown in the figure, in terms of vertical force, assuming that the overall force balance after the connection, the shear bearing capacity N that all expansion bolts 7 can withstand within the unit length range is V Should be equal to the concrete purlin 2 self-weight load N 1 , and the sum of the uniformly distributed construction loads are equal, that is, within a unit length, the sum of the vertical forces F in the force system of the connection structure is equal to zero, as shown in formula (3): (3); Where: N V : The total shear bearing capacity of all expansion bolts 7 on the concrete purlin 2 within unit length; N 1 : Self-weight load of concrete purlin 2 within unit length; q: Construction uniformly distributed load on concrete purlin 2 within unit length; F: vertical force in the force system of the connection structure within unit length; The tensile bearing capacity that all expansion bolts 7 can withstand is N F The bending moment generated should be equal to the self-weight load N of the concrete purlin 2 1, the bending moments generated by the uniformly distributed construction load q are equal, that is, within a unit length, the sum of the bending moments M of the force system of the connection structure is equal to zero, as shown in formula (4): (4); Where: N F : The total tensile bearing capacity of all expansion bolts 7 on the concrete purlin 2 per unit length; M: Bending moment of the connecting structure force system per unit length; h: height of concrete purlin 2.

[0039] Among them, the shear bearing capacity N of all expansion bolts 7 is V represents the sum of the shear bearing capacity of several expansion bolts 7, and equation (5) is obtained: N V =N V1 +N V2 +N V3 +…+N Vn (5); Where: N V1 、N V2 、N V3 ,…N Vn : Shear bearing capacity of each row of expansion bolts 7 from bottom to top within unit length.

[0040] In this embodiment, N V =N V1 +N V2 +N V3 It can be understood that each row mentioned above is because: there are a number of triangular brackets 3 per unit length, each triangular bracket 3 has n expansion bolts 7 from bottom to top, and then a number of triangular brackets 3 can form n rows of expansion bolts 7 .

[0041] In terms of vertical force, no matter how far the expansion bolts 7 are from the concrete purlin 2, it can be considered that in terms of vertical force balance, the vertical forces on each expansion bolt 7 are equal, so formula (6) is obtained: N V1 =N V2 =N V3 =…=N Vn =N V / n(6); Similarly, the tensile bearing capacity N that all expansion bolts 7 can withstand F Represents the sum of the tensile bearing capacity of several expansion bolts 7, but the lateral force borne by the bottom expansion bolt 7 can be ignored, so it is assumed that from the bottom to the top, the tensile bearing capacity of the second expansion bolt 7 is N F1 , so we can get formula (7): N F =N F1 +N F2 +N F3 +…+N Fn-1 (7); Where: N F1 、N F2 、N F3 ,…N Fn-1 : The tensile bearing capacity of each row of expansion bolts 7 from bottom to top within a unit length, except for the expansion bolts 7 at the bottom.

[0042] In this embodiment, N F =N F1 +N F2 .

[0043] However, unlike the vertical force, since the centroid of the concrete purlin 2 and the centroid of the triangular bracket 3 are not actually in the same plane, the force on each expansion bolt 7 on the triangular bracket 3 in the horizontal direction is actually different. This embodiment has previously assumed that: the triangular bracket 3 is absolutely rigid, the expansion bolt 7 is elastic, and the bolt connection is designed according to elasticity; the neutral axis of all expansion bolts 7 is located at the centroid of the bottom row of expansion bolts 7, and the tension on each expansion bolt 7 is proportional to its distance from the neutral axis; therefore, equations (8) and (9) can be obtained: N F1 / y 1 =N F2 / y 2 =N F3 / y 3 =…=N Fn-1 / y n-1 (8); N F1 ={y 1 / y 2}*N F2 ={y 1 / y 3}*N F3 =…={y 1 / y n-1}*N Fn-1 (9); Always: y 1 ,y 2 …y n-1 : From bottom to top on the upper side, the distance from each row of expansion bolts 7 to the neutral axis of the bottom expansion bolt 7; It is known that the spacing L between the expansion bolts 7 is fixed, so formula (10) can be obtained: y 1 ={1 / 2}y 2={1 / 3}y 3 =…={1 / (n-1)}y n-1 (10); Substituting equation (10) into equation (9), we can get equation (11): N F1 ={1 / 2}N F2 =…={1 / (n-1)}N Fn-1 (11); Substituting equation (11) into equation (7), we can get equation (12): N F ={n*(n-1) / 2}*N F1 (12); Before construction, the known quantities that can be obtained are: construction uniform load q, length, height, and width of the construction concrete purlin 2. According to the weight of steel bars and concrete required for the concrete purlin 2, the self-weight N of the concrete purlin 2 can be calculated. 1 Substituting these data into formula (3), we can obtain the total shear bearing capacity N borne by all expansion bolts 7 within the known length range of the concrete purlin 2. V .

[0044] In addition, since the hanger bar 4 is set at the centroid of the concrete purlin 2, substituting formula (1) into formula (4) can be obtained that within the known length range of the concrete purlin 2, the total tensile bearing capacity N borne by all expansion bolts 7 is F .

[0045] It is understandable that expansion bolts 7 of different specifications have different shear bearing capacity and tensile bearing capacity. Each specification of expansion bolts 7 has its own shear bearing capacity and tensile bearing capacity. When selecting the specifications of expansion bolts 7, it is necessary to ensure the stability of the overall force. According to formula (9), it can be seen that the tensile bearing capacity of the selected expansion bolt 7 is greater than N Fn-1 That is, find the value of N Fn-1 The value of can determine the specification of the expansion bolt 7 used.

[0046] Substituting equation (11) into equation (12), we get equation (13): N F ={n / 2}*N Fn-1 (13); Substituting equation (13) into equation (4) we can obtain N Fn-1 The relationship between , and n can be obtained through formula (2), so formula (2) is also substituted into formula (4) to obtain formula (14): N Fn-1 =-(N 1 b+qb 2 )L / {(h+a / 2)(a+L)}(14); And N 1 , b, q, L, and h are all known quantities. Substituting them into equation (14) yields N Fn-1 , so that the maximum tensile bearing capacity of the expansion bolt 7 can be obtained, but at this time N Fn-1 It is the common tensile bearing capacity of all the expansion bolts 7 in the nth row. There is still a missing variable here, namely the number m of the triangular brackets 3.

[0047] Assume that, on a triangular bracket 3, the tensile bearing capacity of the nth expansion bolt 7 from bottom to top is N Fn-1 ', that is, the tensile bearing capacity of the top expansion bolt 7 on a single triangular bracket 3 is N Fn-1 ', then we can get formula (15): N Fn-1 =mN Fn-1 '(15); Where: N Fn-1 ': The tensile bearing capacity of the top expansion bolt 7 on a single triangular bracket 3; m: The number of triangular brackets 3 on the concrete purlin 2 per unit length.

[0048] In addition, substituting equations (2), (5), and (6) into equation (3) can obtain N Vn ; Similarly, the N obtained at this time Vn is the common shear bearing capacity of all the n-th row of expansion bolts 7. Assume that, on a triangular bracket 3, the shear bearing capacity of the n-th expansion bolt 7 from bottom to top is N Vn ', that is, the shear bearing capacity of the top expansion bolt 7 on a single triangular bracket 3 is N Vn ', we can get formula (16): N Vn =m N Vn '(16); Where: N Vn ': Shear bearing capacity of the top expansion bolt 7 on a single triangular bracket 3; Then combine equation (15) and equation (16) to obtain equation (17): N Vn / N Fn-1 =N Vn ' / N Fn-1 '(17); N Fn-1 According to formula (14), N Vn According to formula (2), formula (3), formula (5), and formula (6), we can find out that N Vn ' / N Fn-1', according to which the specification of the expansion bolt 7 in the nth row can be determined, and thus the specification of the expansion bolt 7 to be used next can be determined. It should be noted that the shear bearing capacity of the determined expansion bolt 7 specification should be greater than or equal to the calculated N Fn-1 ' value.

[0049] Then, according to the determined expansion bolt 7 specifications, the corresponding N Vn 'or N Fn-1 Substitute into formula (15) or formula (16) to find the number m of triangular brackets 3 on the concrete purlin 2 within the unit length range. Since the triangular brackets 3 are evenly distributed on the concrete purlin 2 within the unit length range, the spacing of the triangular brackets within the unit length range can be obtained. It can be understood that the construction length of the concrete purlin 2 to be constructed includes a certain multiple of the unit length. According to the calculation result of the unit length, the calculation result within the construction length can be easily obtained.

[0050] According to the above calculation results, the corresponding specifications and the corresponding number of triangular brackets 3 are manufactured, the corresponding number of hanging rods 4 are manufactured, the hanging rods 4 are fixed to the triangular brackets 3, and a sufficient number of expansion bolts 7 of the required specifications are prepared.

[0051] S2, excavating downward along the foundation pit retaining structure 1 until the bottom elevation of the concrete purlin 2, and roughening the joint between the concrete purlin 2 and the retaining structure 1 on the retaining structure 1; S3, support formwork tied concrete purlin 2 steel bars, the hanger 4 anchored into the concrete purlin 2 centroid position of the steel mesh, and the lower side of the triangular bracket 3 and the top side of the concrete purlin 2 steel bars welded, the upper side by a plurality of expansion bolts 7 and the retaining structure 1 fixed; S4. Pour concrete purlin 2.

[0052] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A connection structure between a concrete purlin and a glass fiber reinforced reinforcement, characterized in that: It includes a retaining structure, which is made of glass fiber reinforcement as the skeleton and poured concrete; The enclosure structure is fixedly connected to the concrete enclosure purlin through triangular brackets and hanging rods; multiple triangular brackets are evenly distributed above the length direction of the concrete enclosure purlin, and the triangular brackets include a fixedly connected upper side, a lower side, and a beveled side, and the two sides are perpendicular to each other; The upper side is fixed to the retaining structure by a number of expansion bolts, the lower side is welded to the upper steel bars of the concrete purlin, the lower side is fixedly connected to the upper part of the hanger, the lower part of the hanger extends into the concrete purlin, and then is cast and fixed together with the concrete purlin.

2. The connection structure of a concrete purlin and a glass fiber reinforcement enclosure as claimed in claim 1, characterized in that: The hanger bar is arranged at the centroid position of the concrete purlin; and a plurality of the expansion bolts are arranged at a set interval.

3. The connection structure of a concrete purlin and a glass fiber reinforcement enclosure as claimed in claim 1, characterized in that: The triangular bracket is formed by welding angle steels, and the lengths of the two sides are equal. The two ends of the hypotenuse are not connected to the ends of the sides. A certain distance is reserved outside the position where the two ends of the hypotenuse are connected to the two sides to ensure that there is sufficient installation space when installing the expansion bolts at the upper end of the upper side.

4. The connection structure of a concrete purlin and a glass fiber reinforcement enclosure as claimed in claim 1, characterized in that: The hanger bar is made of steel bars into a "U" shape, wherein the upper end of the hanger bar is bent in an arc and the lower end of the straight line is bent at 90°.

5. A construction method for a connection structure of a concrete purlin and a glass fiber reinforced enclosure, using a connection structure of a concrete purlin and a glass fiber reinforced enclosure as claimed in any one of claims 1 to 4, characterized in that: The specific steps are as follows: S1. Determine the number of triangular brackets used in the concrete purlin per unit length and the specifications of the expansion bolts through calculation; and make the triangular brackets and hanging bars; S2. Dig down along the foundation pit retaining structure until the bottom elevation of the concrete purlin. Roughen the joint between the concrete purlin and the retaining structure on the retaining structure. S3, support the formwork and tie the concrete purlin reinforcement, anchor the hanger into the steel mesh at the centroid of the concrete purlin, weld the lower side of the triangular bracket to the top side reinforcement of the concrete purlin, and fix the upper side to the enclosure structure through multiple expansion bolts; S4. Pour concrete purlins.

6. The construction method of the connection structure of the concrete purlin and the glass fiber reinforcement enclosure as claimed in claim 5 is characterized in that: In S1, firstly, the height and width of the concrete purlin are obtained, the specifications of the triangular bracket are determined, and the number of expansion bolts required to be set on the triangular bracket is calculated; Next, determine the deadweight of the concrete purlin within the unit length and the uniformly distributed construction load, and then obtain the total shear bearing capacity and total tensile bearing capacity of all expansion bolts within the unit length based on the force balance; Then find out the tensile and shear bearing capacities of the top row of expansion bolts; determine the specifications of the expansion bolts to be used; Calculate the number of triangular brackets based on the determined expansion bolt specifications.

7. The construction method of the connection structure of the concrete purlin and the glass fiber reinforcement enclosure as claimed in claim 6 is characterized in that: The number of expansion bolts required to be provided on the triangular bracket is calculated by the following formula: a=b / 2; a=L(n-1); Where: b: Concrete purlin width; a: The distance from the top expansion bolt to the bottom expansion bolt on the upper side; L: Expansion bolt spacing. According to construction experience, the spacing L is 300-400mm. n: The number of expansion bolts on a single triangular bracket.

8. The construction method of the connection structure of the concrete purlin and the glass fiber reinforcement enclosure as claimed in claim 6 is characterized in that: The total shear bearing capacity and total tensile bearing capacity of all expansion bolts on the concrete purlin within unit length are calculated as follows: ； ； Where: F: vertical force in the force system of the connection structure within unit length; M: Bending moment of the connecting structure force system per unit length; N V : The total shear bearing capacity of all expansion bolts on the concrete purlin within unit length; N F : The total tensile bearing capacity of all expansion bolts on the concrete purlin within unit length; N1: Self-weight load of concrete purlin per unit length; q: Construction uniformly distributed load on the concrete purlin within unit length; h: height of concrete purlin.

9. The construction method of the connection structure of the concrete purlin and the glass fiber reinforcement enclosure as claimed in claim 6, characterized in that: The calculation formulas for the tensile bearing capacity and shear bearing capacity of the top row of expansion bolts are as follows: N V1 =N V2 =N V3 =…=N Vn =N V / n; N Fn-1 =-(N1b+qb 2 )L / {(h+a / 2)(a+L)}; Where: N V1 、N V2 、N V3 ,…N Vn : The shear bearing capacity of each row of expansion bolts from bottom to top within the unit length; N F1 、N F2 、N F3 ,…N Fn-1 : The tensile bearing capacity of each row of expansion bolts from bottom to top within unit length, except for the expansion bolts at the bottom.

10. The construction method of the connection structure of the concrete purlin and the glass fiber reinforcement as claimed in claim 6, characterized in that: The expansion bolt specifications are determined by the following formula: N Vn / N Fn-1 =N Vn ’ / N Fn-1 ’; Where: N Fn-1 ': tensile bearing capacity of the top expansion bolt on a single triangular bracket; N Vn ': Shear bearing capacity of the top expansion bolt on a single triangular bracket; The number of the triangular brackets is determined by the following formula: N Vn =m N Vn ’; Where: m: The number of triangular brackets on the concrete purlin per unit length.

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