Variable-width cast-in-situ box girder formwork and wing plate support integrated structure and construction method

Abstract

The application discloses a variable-width cast-in-situ box girder formwork and wing plate support integrated structure and a construction method, which comprises full-supports, longitudinal bottom groove steels, transverse horizontal square timbers, multiple wing plate supports, vertical square timbers, railings, bottom formworks and wing plate formworks, etc., wherein multiple cross-fixed inclined supports are arranged between the multiple wing plate supports and the full-supports, the multiple wing plate supports and the wing plate formworks are connected through lower hinges and upper hinges, each wing plate support is composed of a bottom horizontal rod, an inner inclined rod, a vertical rod, a middle inclined rod and an upper inclined rod at the same width of a main line of the box girder, and a variable-width wing plate support is composed of a side inclined rod welded at an outer end of the bottom horizontal rod, the upper inclined rod, the inner inclined rod, the vertical rod and the middle inclined rod, and the longitudinal square timbers and the wing plate formworks are sequentially arranged on the variable-width wing plate support, so that the application has the structural advantages of simple structure, convenient construction, safety and reliability, energy saving and environmental protection, high cost performance and the like, and in combination with the corresponding construction method, the application also has remarkable economic and social benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of bridge energy-saving construction, in particular to a variable-width cast-in-situ box girder formwork and wing plate support integrated structure and a construction method. BACKGROUND

[0002] In recent years, the concept of prefabricated assembly and rapid construction in line with low-carbon and green bridge construction has been gradually recognized and developed rapidly in China. However, the upper structure of small-radius curve ramp or main line variable-width section still needs to use the traditional cast-in-situ method, and full-support is one of the main methods for cast-in-situ box girder upper structure of bridge. In the full-support cast-in-situ box girder construction of variable-width wing plate to realize the variable-width of box girder bridge deck, the commonly used method is to widen the width of full-support along with the widening of wing plate, which not only increases the ground width occupied by full-support, but also brings great difficulty to the reconstruction project which needs to maintain ground traffic in a limited area, and increases the cost, especially for high piers. Therefore, in order to embody the concept of "safety, durability, energy saving, green and sustainable development" of bridge construction, it is necessary to improve the existing variable-width cast-in-situ box girder support erection method. SUMMARY

[0003] The technical problem to be solved by the present application is to overcome the defects of the prior art and provide a variable-width cast-in-situ box girder formwork and wing plate support integrated structure and a construction method which are simple in structure, convenient in construction, safe and reliable, energy-saving and environmentally friendly, and high in cost performance.

[0004] The technical problem of the present application is solved by the following technical scheme:

[0005] A variable-width cast-in-situ box girder formwork and wing plate support integrated structure, comprising a full-support erected on the foundation, the top of the full-support is provided with a plurality of longitudinally arranged bottom channel steels and transversely arranged cross beams, a plurality of frame-type wing plate supports and longitudinal beams are arranged longitudinally and spaced apart, a bottom formwork is installed on the transversely arranged cross beams, and a wing plate formwork is installed on the longitudinal beams, the outer end of the wing plate support is provided with a protective railing; a plurality of cross-fixed inclined braces are arranged between the plurality of wing plate supports and the full-support, and the plurality of wing plate supports and the wing plate formwork are connected through lower hinges and upper hinges; each of the wing plate supports is composed of a bottom horizontal rod with upwardly opening grooves, an inner inclined rod, a vertical rod, a middle inclined rod and an upper inclined rod with downwardly opening grooves, which are horizontally arranged at the same width as the main line of the box girder; the bottom horizontal rod, the upper inclined rod and the edge inclined rod are all made of channel steel, the grooves of the bottom horizontal rod and the edge inclined rod are upwardly opening, and the groove of the upper inclined rod is downwardly opening; the inner inclined rod, the vertical rod and the middle inclined rod are all steel pipes; the variable-width section of the main line of the box girder is a edge inclined rod with upwardly opening grooves welded at the outer end of the bottom horizontal rod, the outer end of the edge inclined rod is fixed with the outer end of the upper inclined rod, the upper inclined rod extends inwardly to jointly form a variable-width wing plate support with the inner inclined rod, the vertical rod and the middle inclined rod, and longitudinal beams and wing plate formworks are sequentially arranged on the variable-width wing plate support.

[0006] The bottom flat bar and the upper inclined bar are firmly welded with the inner inclined bars, the vertical bars and the middle inclined bars to form a frame structure, and the bottom flat bar and the upper inclined bar are whole continuous channel steels; the whole length of the widened section is , and the width of the maximum widened section is The wing plate support is divided into two sections: the first section is composed of the upper inclined bar, the inner inclined bars, the vertical bars, the middle inclined bars and the bottom flat bar, the length of the vertical center line is , and is regarded as an elastic foundation beam supported on the longitudinal bottom channel steel and the transverse horizontal timber, the upper inclined bar and the bottom flat bar equally divide each length , and are respectively the upper and lower end points of the inner inclined bars, the vertical bars and the middle inclined bars; the second section The widened section of the wing plate support is a cantilever frame, and the upper inclined bar and the edge inclined bar equally divide each length , and are respectively the upper and lower end points of the vertical bars and the middle inclined bars; the load acting on the wing plate support is divided into two parts: the first part is the sum of the static load of the self weight of the wing plate formwork and the longitudinal timber and the dynamic load of the vibrating force of the vibrating cement concrete ; the second part is the self weight load of the reinforced concrete of the widened wing plate, the thickness of the joint between the wing plate and the cast-in-place box girder is , the thickness of the end of the wing plate is , the length of the wing plate is , and the load on the wing plate support is distributed in a trapezoidal shape, wherein the maximum distributed load is , and the minimum distributed load is ; the reaction force of the longitudinal bottom channel steel and the transverse horizontal timber on the first section of the wing plate support conforms to the Winkler hypothesis , and the longitudinal spacing of each wing plate support is According to the elastic foundation beam theory and the structural mechanics, the following calculation formula is obtained:

[0007] Formula one, calculation of load and moment of inertia

[0008] The center line x axis of the wing plate support is the average value of the height of the center of the bottom flat bar and the upper inclined bar, and the height of the center of each inner inclined bar, vertical bar and middle inclined bar is the y axis, and then the calculation load of the wing plate support, the load of the elastic foundation beam supported on the longitudinal bottom channel steel and the transverse horizontal timber and the equivalent bending moment of inertia of the frame are:

[0009]

[0010] In the formula,

[0011] (1) the total moment of inertia of the upper inclined bar to the x axis

[0012] The notch of the upper inclined rod faces downward, and the effect of the notch angle of the upper inclined rod on the centroid of the body itself is ignored. The moment of inertia of the centroid of the body itself I cgx下 According to the relevant information of the type and specification of the channel steel, the area per unit length is Then

[0013]

[0014] (2) The total moment of inertia of the bottom flat rod about the x-axis

[0015] The notch of the upper inclined rod faces upward, and the moment of inertia of the centroid of the body itself I sxgx上 According to the relevant information of the type and specification of the channel steel, the area per unit length is

[0016]

[0017] (3) The moment of inertia of a single vertical rod about the x-axis and the moment of inertia about the y-axis and the total moment of inertia of the vertical rods about the x-axis

[0018]

[0019] The moment of inertia of a single vertical rod about the y-axis

[0020]

[0021] (4) The moment of inertia of the inner inclined rod and the upper inclined rod about the x-axis

[0022] The moment of inertia of a single inner inclined rod or upper inclined rod about the x-axis is calculated by the rotation of the vertical rod about the centroid angle

[0023]

[0024] Formula two, calculate the internal force at the outer end of the first part of the wing plate support A n , B n

[0025] Disconnect the connection between the first part and the second part of the wing plate support A n , B n , get

[0026]

[0027] ​

[0028] Equation three, the elastic foundation beam foundation reaction force distribution of the wing plate support

[0029] The first part of the wing plate support under the action of load And , , The wing plate support elastic foundation beam differential equation and initial parameter solution is

[0030]

[0031]

[0032] In the formula

[0033]

[0034] According to the wing plate support and wing plate formwork integrated design requirements, the first part of the wing plate support A 1 End is elastic fixed, A n End is free, then y 0 =0, the initial parameter solution is

[0035]

[0036] The above formula is substituted into the 、 In equation two, 、 、 , get

[0037]

[0038] From equation one, equation two and equation three, the internal force of the bottom flat bar, inner inclined bar, vertical bar, middle inclined bar, upper inclined bar and edge inclined bar of the two parts of the wing plate support can be obtained by structural mechanics. The strength and stiffness of each bar meet the strength and stiffness requirements of the materials used;

[0039] The symbols in equation one, equation two and equation three are defined as follows:

[0040] Respectively, the thickness of the cast-in-place box girder wing plate root and end, ;

[0041] Respectively, the width at the starting end and the width at the end of the variable width section of the cast-in-place box girder wing plate when the variable width section length is ;

[0042] ​ The width of the cast-in-place box beam wing plate as the calculation width of the elastic foundation beam model, i.e. the width of the upper inclined rod or the bottom flat rod,

[0043] The equal interval between the inner inclined rod, the vertical rod and the middle inclined rod supported by each wing plate,

[0044] The interval between each wing plate support of the cast-in-place box beam wing plate, the length of the first section of the wing plate support at the centroid of the widened end supported on the longitudinal bottom channel steel and the transverse cross beam, the full length of the widened section of the cast-in-place box beam wing plate, and the length of the cantilever part of the second section of the wing plate support at the widened end,

[0045] The height of the wing plate support at the centroid of the starting point of the first section of the wing plate support, the height of the wing plate support at the centroid of the end of the first section of the wing plate support, the height of the wing plate support at the centroid of each subsection of the first section of the wing plate support, and the height of the wing plate support at the centroid of the end of the second section of the wing plate support,

[0046] The horizontal coordinate value of the centroid of the starting point of the first section of the wing plate support as the horizontal coordinate value of the elastic foundation beam, and the centroid of the wing plate support is also used as the horizontal coordinate when calculating the inner inclined rod, the vertical rod and the middle inclined rod,

[0047] The vertical coordinate value of the centroid of the starting point of the first section of the wing plate support as the vertical deformation curve of the elastic foundation beam, The centroid of the wing plate support is also used as the vertical coordinate when calculating the inner inclined rod, the vertical rod and the middle inclined rod,

[0048] The centroid of the inner inclined rod, the vertical rod and the middle inclined rod of the wing plate support is the longitudinal coordinate of the cast-in-place box beam wing plate,

[0049] The outer diameter and the inner diameter of the inner inclined rod, the vertical rod and the middle inclined rod of the wing plate support,

[0050] The longitudinal coordinate of the outer diameter and the inner diameter of the inner inclined rod, the vertical rod and the middle inclined rod in the longitudinal direction of the cast-in-place box beam wing plate,

[0051] ​​​​​​​​​The length of the inner inclined rod welded between the longitudinal bottom channel steel and the horizontal transverse beam at the widened end of the wing plate support section is ; The length of the vertical rod welded between the widened end of the wing plate support cantilever section and the middle inclined rod is ; The number of divisions of the middle inclined rod is ;

[0052] The angle between the longitudinal axis of the wing plate support including the inner inclined rod, the upper inclined rod, and the side inclined rod and the horizontal line passing through the centroid is ;

[0053] The node number at the intersection of the inner inclined rod, the vertical rod, and the bottom horizontal rod or the side inclined rod of the wing plate support. The numbering of the starting end to the end of the first section of the wing plate support is 1, 2, 3,..., n, and the numbering of the starting end to the end of the second section of the wing plate support is 1, 2, 3,..., m.

[0054] The unit weight of the cast-in-place box girder wing plate reinforced concrete is ;

[0055] The sum of the static load of the wing plate formwork and the longitudinal beam and the dynamic load of the vibrating force of the vibrating cement concrete ;

[0056] The sum of the static load of the wing plate formwork and the longitudinal beam and the dynamic load of the vibrating force of the vibrating cement concrete , the total weight of the cast-in-place box girder wing plate reinforced concrete, the distributed load at the starting point of the wing plate support, the load at the end of the first section of the wing plate support, and the distributed load at the outermost end of the wing plate support ;

[0057] The reaction force of the longitudinal bottom channel steel and the horizontal transverse beam of the first section of the wing plate support as an elastic foundation beam conforms to the Winkler hypothesis , ;

[0058] The foundation reaction coefficient of the Winkler hypothesis is obtained by consulting relevant manuals or through full-support preloading tests ;

[0059] The coefficient of the elastic foundation beam is , ;

[0060] The elastic modulus of the channel steel and the steel pipe is ;

[0061] —The wing plate supports the equivalent moment of inertia of the first segment, which acts as an elastic foundation beam. ;

[0062] —These represent the total moments of inertia of the upper diagonal member, the bottom horizontal member, the vertical member, and including the inner diagonal member and the middle diagonal member. ;

[0063] —These represent the moments of inertia of a single upper diagonal member, a bottom horizontal member, a vertical member, and including inner and middle diagonal members. ;

[0064] —respectively, for single vertical poles in The moment of inertia of the interval, a single vertical rod in Moment of inertia of the interval, ;

[0065] —These are the moments of inertia about the centroid x-axis of a single upward-facing or downward-facing single-angled or bottom-flat bar, respectively, and the cross-sectional area of ​​the single upward-facing or bottom-flat bar. These values ​​were obtained by consulting relevant materials handbooks. ;

[0066] —These represent the tension of the upper diagonal brace and the compressive force of the bottom flat brace at the point where the wing plate of the cast-in-place box girder widens and supports the section at the end of the first segment and the beginning of the second segment. ;

[0067] —The moment at the end of the cast-in-place box girder flange where the flange supports the point where the first segment ends and the second segment begins. ;

[0068] —These are the relevant parameters for calculating the cast-in-place box girder flange supported as an elastic foundation beam, and are dimensionless.

[0069] —These represent the deflection, rotation, shear force, and bending moment at the starting end of the cast-in-place box girder supported by the flange on an elastic foundation. .

[0070] The wing plate support is an integrated structure formed by connecting the upper and lower hinges at the starting end with the hinge support preset in the cast-in-place box girder formwork.

[0071] The two ends of the inner inclined rod are respectively welded with the bottom horizontal rod and the upper inclined rod to form a common node, the two ends of the vertical rod and the middle inclined rod are respectively welded with the bottom horizontal rod and the edge inclined rod to form a common node, the inclination angle of the upper inclined rod with the horizontal line is the same as the inclination angle of the bottom surface of the wing plate formwork, the inclination angle of the inner inclined rod is the same as the inclination angle of the side surface of the wing plate formwork, and the inclination of the middle inclined rod is determined by the positions of the above two nodes.

[0072] The lower hinge and the upper hinge are both steel parts, one end of the lower hinge or the upper hinge is embedded in the side surface of the wing plate formwork, and the other end is welded at the end of the inner inclined rod and the bottom horizontal rod close to the wing plate formwork, the lower hinge and the upper hinge are connected by round steel, and the wing plate formwork or the wing plate support forms mutual rotation.

[0073] The bottom formwork and the wing plate formwork are both steel parts, and are respectively supported on the transverse cross beams and the longitudinal beams and enclosed to form the bottom plate, the web plate and the wing plate of the cast-in-place box girder.

[0074] The longitudinal bottom channel steel is laid on the top of the full-frame support, and the transverse cross beam is laid on the longitudinal bottom channel steel as the base of the cast-in-place box girder formwork.

[0075] The longitudinal beam is a longitudinal square timber placed between each pair of adjacent wing plate supports.

[0076] The foundation is the basis of the full-frame support, the cast-in-place box girder is the superstructure of the elevated bridge, and the widened section of the main line of the box girder is realized by widening the wing plate formwork to widen the cast-in-place box girder deck.

[0077] The construction method of the widened cast-in-place box girder formwork and the wing plate support integrated structure includes the following steps:

[0078] Step one, determine the size of the widened cast-in-place box girder formwork and the wing plate support integrated structure

[0079] 1. According to the actual situation of the widened cast-in-place box girder and the full-frame support, initially determine the size, arrangement form and selection of engineering materials of the widened cast-in-place box girder formwork and the wing plate support integrated structure;

[0080] 2. Calculate and determine the size, arrangement form and selection of engineering materials of the widened cast-in-place box girder formwork and the wing plate support integrated structure by Formulas 1, 2 and 3;

[0081] 3. Prepare the construction organization design document and organize the construction;

[0082] Step two, set up the full-frame support and the cast-in-place box girder formwork

[0083] 1. Select the materials of the full-frame support according to the relevant standards and specifications, and design the structure of the full-frame support according to the design load;

[0084] 2. Measure and layout, determine the position, elevation and installation width of the full support according to the design drawings;

[0085] 3. Full support erection process: support foundation acceptance → construction measurement and positioning → installation of adjustable base to the designed height → installation of vertical rods and cross rods → installation of inclined rods → correction of horizontal and vertical with level gauge → installation of vertical rods and cross rods in the previous step → installation of inclined rods → repeat the above steps until the designed height → measurement and positioning review → installation of adjustable top support to the designed height → full support load preloading meets the design requirements → installation of longitudinal bottom channel steel → installation of transverse cross beams → laying of bottom formwork → installation of wing plate support → installation of inclined bracing → installation of longitudinal beams → installation of wing plate formwork → hinge connection of wing plate support and wing plate formwork → installation of support guardrails → overall acceptance of full support, wing plate support, bottom formwork and wing plate formwork;

[0086] In order to strengthen the stability of the full support system, scissors are installed on the whole full support or connected with steel pipe around the bridge pier column, and displacement monitoring is strengthened through pre-buried monitoring points during the installation and use of the full support system to ensure the safety of the support;

[0087] Step three, steel reinforcement binding and cement concrete pouring of cast-in-place box girder

[0088] 1. Steel reinforcement installation of cast-in-place box girder is divided into two stages, the first stage is to install the bottom plate and web steel reinforcement first, and the second stage is to install the top plate steel reinforcement and wing plate steel reinforcement after the first concrete pouring, and the steel reinforcement manufacturing and installation quality meets the design and standard specification requirements;

[0089] 2. After the installation of web steel reinforcement of cast-in-place box girder, prestressed pipe can be installed, and this process is completed before core mold installation; prestressed pipe, prestressed steel strand, anchor and clamp of cast-in-place box girder meet the national technical quality standards, steel strand is strictly prohibited from being drenched in rain during storage to prevent rust, and is not allowed to be contaminated with oil;

[0090] 3. Cast-in-place box girder concrete is poured in two times by pumping, and the overall pouring sequence is first-time bottom plate and web concrete pouring → second-time top plate and flange plate concrete pouring, and the interval time between the two times of pouring is not more than 10 days;

[0091] 4. After the factory delivery of prestressed steel strand, batch acceptance is carried out, and when acceptance, the quality certificate, packaging method and logo content are checked for completeness and correctness, and the mechanical properties such as tensile strength and elongation are inspected according to the sampling standard; anchor must have factory delivery certificate, and when entering the site, sampling is carried out according to the regulation, and appearance inspection and hardness test are carried out; steel strand is put into the hole one by one by using a threading machine, the front of the steel strand should be sleeved with a bullet-shaped cap, and the steel strand is pushed into the hole by using the threading machine to control the appropriate speed;

[0092] 5. The cast-in-place box girder prestress tension adopts intelligent tension construction technology. The system also sends instructions from the host according to preset procedures to synchronously control each mechanical action of each device, and automatically completes the entire tension process;

[0093] 6. The prestress duct grouting adopts vacuum-assisted grouting technology, which is strictly performed according to relevant standards and specifications. Technical training is provided to the operators before construction, and the grouting is strictly performed according to the specifications and guidelines during construction to ensure the compactness and reliability of the grouting;

[0094] 7. After the duct grouting, the anchor end cement slurry is flushed clean, the supporting pad is removed, the anchor and the end face concrete are cleaned, and the end concrete is chipped. The anchor end reinforcement mesh is set, the end sealing concrete is poured after the sealing head formwork is fixed, the sealing concrete has the same strength grade as the main concrete, and careful vibration is performed. After demolding, attention should be paid to curing. The anchor end arrangement should be strictly constructed according to the design drawings;

[0095] 8. Concrete curing: After the pouring of the cement concrete is completed, the top surface of the cast-in-place box girder is roughened to a depth of 1mm to 2mm. The top surface is covered with plastic film and geotextile for moisture curing. Initial uninterrupted watering and spraying should not be less than 48h to prevent early shrinkage cracking. After 48h, the concrete enters the regular curing period, and the concrete curing time is not less than 7d;

[0096] Step four, cast-in-place box girder formwork and full-frame support removal

[0097] After all the prestress construction is completed and the concrete strength and duct grouting strength reach 100% of the design strength, the cast-in-place box girder formwork and full-frame support can be removed after the approval of the supervising engineer;

[0098] 1. The principle of full-frame support removal is to complete it in a small amount, in several times, and gradually, so that the cast-in-place box girder can gradually bear the load and avoid quality accidents during the removal process;

[0099] 2. The full-frame support removal should be performed according to the principle of removing the middle span first, then the rear span, removing the middle span first, and then the top of the pier. The removal must be small, slow, symmetrical, and uniform, and must be checked before gradually increasing the falling amount. It is not allowed to remove a large amount at the beginning to ensure safety;

[0100] 3. The full-frame support, wing plate support, bottom formwork, and wing plate formwork should be slowly lowered to the ground during the removal process. They should not be thrown randomly to prevent damage to the formwork. They should be cleaned, repaired, and stored properly for future use.

[0101] Compared with the prior art, the present application mainly provides a variable-width cast-in-situ box girder formwork and wing plate support integrated structure, which can set up a wing plate support to adjust the bridge width according to the erection characteristics of the full-support; the present application has the following structural advantages: first, the variable-width cast-in-situ box girder formwork and the frame-type wing plate support form an integrated structure, which can make the deformation of the cast-in-situ box girder formwork and the wing plate support structure coordinated and the structure stress scientific; second, the length of the cantilever end of the wing plate support can be flexibly adjusted to meet the variable-width requirement of the bridge and has strong adaptability; third, the bridge width can be actually adjusted, but the lateral width of the full-support can remain unchanged, which saves materials, machinery and labor, saves energy and reduces emissions, and is green and environmentally friendly; fourth, the calculation method provided for the wing plate support design is clear in principle, scientific and reasonable, practical and easy to implement, can guide the construction of the variable-width cast-in-situ box girder formwork and wing plate support integration, and improves the safety performance and engineering quality. Therefore, the present application has the use advantages of simple structure, convenient construction, safety and reliability, energy saving and environmental protection, and high performance-price ratio, and in combination with the corresponding construction method, has high economic and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0102] Figure 1 is a structural schematic view of the left half elevation and the right half elevation of the present application.

[0103] Figure 2 is a plan view of Figure 1 .

[0104] Figure 3 is an internal force analysis diagram of a single-span wing plate support.

[0105] Figure 4 is a calculation diagram of the moment of inertia of a steel pipe.

[0106] Figure 5 is a force calculation diagram of an elastic foundation beam of a single-span wing plate support. DETAILED DESCRIPTION

[0107] The embodiments of the present application will be further described in detail below with reference to the above drawings.

[0108] As shown in Figures 1-5 , 1. foundation, 2. full-support, 21. inclined support, 3. cast-in-situ box girder, 4. longitudinal bottom channel steel, 51. transverse horizontal timber, 52. longitudinal timber, 6. wing plate support, 61. bottom flat rod, 62. inner inclined rod, 63. vertical rod, 64. middle inclined rod, 65. upper inclined rod, 66. edge inclined rod, 67. lower hinge, 68. upper hinge, 71. bottom formwork, 72. wing plate formwork, 8. railing.

[0109] The variable-width cast-in-situ box girder formwork and wing plate support integrated structure and construction method, as shown in Figure 1 , Figure 2The application relates to the field of bridge energy-saving construction, and the structure comprises full-support 2 erected on a foundation 1, a plurality of longitudinal bottom channel steels 4 and transverse cross beams 51 arranged side by side on the top of the full-support, and a plurality of frame-type wing plate supports 6 and longitudinal cross beams 52 arranged at intervals in the longitudinal direction, a bottom form plate 71 is installed on the transverse cross beams 51, and a wing plate form plate 72 is installed on the longitudinal cross beams 52, the bottom form plate 71 and the wing plate form plate 72 jointly form a cast-in-situ box girder form plate, a guardrail 8 is installed on the outer end of the wing plate support 6, a plurality of wing plate supports 6 and the full-support 2 are cross-fixed by a plurality of inclined braces 21 to form a stable cast-in-situ box girder form plate and wing plate support integrated structure with variable width.

[0110] The cast-in-situ box girder form plate and wing plate support integrated structure with variable width is formed by connecting a plurality of frame-type wing plate supports 6 and wing plate form plates 72 at intervals in the longitudinal direction through lower hinges 67 and upper hinges 68, each wing plate support 6 is composed of a bottom horizontal rod 61, an inner inclined rod 62, a vertical rod 63, a middle inclined rod 64 and an upper inclined rod 65 which are horizontally arranged with the notches facing upwards at the same width of the main line of the box girder, the bottom horizontal rod 61, the upper inclined rod 65 and the edge inclined rod 66 are all made of channel steels, the notches of the bottom horizontal rod 61 and the edge inclined rod 66 face upwards, and the notches of the upper inclined rod 65 face downwards, the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64 are all made of steel pipes, the variable width section of the main line of the box girder is formed by welding an edge inclined rod 66 with the notches facing upwards on the outer end of the bottom horizontal rod 61, the outer end of the edge inclined rod is fixed with the outer end of the upper inclined rod 65, the upper inclined rod 65 extends inwardly to jointly form the wing plate support 6 with the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64, and the longitudinal cross beams 52 and the wing plate form plates 72 are sequentially arranged on the wing plate support with variable width to jointly realize the support of the widened wing plate.

[0111] The foundation 1 is the basis of the full-support 2, and has certain strength and rigidity, and can meet the strength and stability requirements of the cast-in-situ box girder 3.

[0112] The cast-in-situ box girder 3 is the superstructure of the elevated bridge, the widened wing plate realizes the widening of the cast-in-situ box girder bridge deck, and the cast-in-situ box girder is formed by laying the cast-in-situ box girder form plate on the full-support 2, binding the steel bars and pouring the cement concrete on site.

[0113] The longitudinal bottom channel steels 4 are laid on the top of the full-support 2, the transverse cross beams 51 are laid on the longitudinal bottom channel steels 4 as the base of the cast-in-situ box girder form plate, the bottom form plate 71 is installed on the transverse cross beams 51, and the longitudinal cross beams 52 are longitudinal square timbers arranged between each wing plate support 6, and the wing plate form plate 72 is installed on the longitudinal cross beams 52.

[0114] The wing plate support 6 is a steel structure integrated with the variable-width cast-in-place box girder formwork, and the wing plate support 6 is connected with the hinge supports of the cast-in-place box girder formwork through the upper hinge 68 and the lower hinge 67 at the starting end to form an integrated structure; the two ends of the inner inclined rod 62 are respectively welded with the bottom horizontal rod 61 and the upper inclined rod 65 to form a common node, the two ends of the vertical rod 63 and the middle inclined rod 64 are respectively welded with the bottom horizontal rod 61 and the side inclined rod 66 to form a common node, and the inclination angle of the upper inclined rod 65 with the horizontal line is the same as the inclination angle of the bottom surface of the wing plate formwork 72, the inclination angle of the inner inclined rod 62 is the same as the inclination angle of the side surface of the wing plate formwork 72, and the inclination of the middle inclined rod 64 is determined by the positions of the above two nodes.

[0115] The lower hinge 67 and the upper hinge 68 are both steel components, one end of the lower hinge or the upper hinge is embedded in the side surface of the wing plate formwork 72, and the other end is welded on the end of the inner inclined rod 62 and the bottom horizontal rod 61 close to the wing plate formwork 72, the lower hinge 67 and the upper hinge 68 are connected by round steel, and the wing plate formwork 72 or the wing plate support 6 is formed to rotate with each other to release stress and protect the wing plate formwork 72 from damage caused by stress concentration.

[0116] The bottom formwork 71 and the wing plate formwork 72 are both steel components, and are respectively supported on the transverse cross beam 51 and the longitudinal beam 52 and enclosed to form the bottom plate, the web plate and the wing plate of the cast-in-place box girder 3, as the formwork of the bound steel bars and the cast-in-place cement concrete of the cast-in-place box girder 3.

[0117] The bottom horizontal rod 61 and the upper inclined rod 65 are firmly welded with the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64 to form a frame structure, and the bottom horizontal rod 61 and the upper inclined rod 65 are whole continuous channel steels; the variable-width section has a total length of , and the maximum variable-width is The wing plate support 6 is divided into two sections: the first section is composed of the upper inclined rod 65, the inner inclined rod 62, the vertical rod 63, the middle inclined rod 64 and the bottom horizontal rod 61, and the length of the vertical center line is , which is regarded as an elastic foundation beam supported on the longitudinal bottom channel steel 4 and the transverse cross beam 51, the upper inclined rod 65 and the bottom horizontal rod are equally divided at each length , which are respectively the upper and lower end points of the installation of the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64; the second section The variable-width part of the length of the wing plate support 6 is a cantilever frame, and the upper inclined rod 65 and the side inclined rod are equally divided at each length , which are respectively the upper and lower end points of the vertical rod 63 and the middle inclined rod 64; the load acting on the wing plate support 6 is divided into two parts: the first part is the sum of the static load of the wing plate formwork 72 and the longitudinal beam 52 and the dynamic load of the vibrating cement concrete ; the second part is the variable-width self-weight load of the steel reinforced concrete of the wing plate, and the thickness of the joint between the wing plate and the cast-in-place box girder 3 is The thickness of the end of the wing plate is The length of the wing plate is The load on the wing plate support 6 is distributed in a trapezoidal shape, wherein the maximum distributed load is and the minimum distributed load is The reaction force of the longitudinal bottom channel steel 4 and the transverse cross beam 51 on the first section of the wing plate support 6 conforms to the Winkler hypothesis The longitudinal spacing of each wing plate support 6 is According to the elastic foundation beam theory and structural mechanics, the following calculation formula is obtained:

[0118] Formula one, calculation of load and moment of inertia

[0119] The wing plate support 6 takes the average value of the center line x axis of the bottom flat bar 61 and the height of the centroid of the upper inclined bar 65 as the center line, and the height centroid of each inner inclined bar 62, vertical bar 63, and middle inclined bar 64 as the y axis. Then, the calculation load of the wing plate support 6, the elastic foundation beam load supported on the longitudinal bottom channel steel 4 and the laid transverse cross beam 51, and the equivalent bending moment of inertia of the frame structure are:

[0120]

[0121] wherein

[0122] (1) The total moment of inertia of the upper inclined bar 65 about the x axis is

[0123] The notch of the upper inclined bar 65 is downward, and the influence of the notch angle of the upper inclined bar 65 on the centroid of itself is ignored. The moment of inertia of the centroid of itself is I cgx下 According to the relevant information of the model and specification of the channel steel, the area per unit length is Then

[0124]

[0125] (2) The total moment of inertia of the bottom flat bar 61 about the x axis is

[0126] The notch of the upper inclined bar 65 is upward, and the moment of inertia of the centroid of itself is I sxgx上 According to the relevant information of the model and specification of the channel steel, then

[0127]

[0128] (3) The moment of inertia of a single vertical bar 63 about the x axis is and the moment of inertia about the y axis is and the total moment of inertia of the vertical bar about the x axis is

[0129]

[0130] Moment of inertia of single vertical strut 63 about y axis

[0131]

[0132] Moment of inertia of inner diagonal strut 62 or upper diagonal strut 65 about x axis

[0133] Moment of inertia of single inner diagonal strut 62 or upper diagonal strut 65 about x axis by vertical strut 63 about centroid Angle calculated

[0134]

[0135] Formula two, calculate the inner force at the outer end of the first part of the wing plate support A n , B n

[0136] Disconnect the connection between the first part and the second part of the wing plate support 6 A n , B n ,

[0137]

[0138]

[0139] Formula three, calculate the elastic foundation beam foundation reaction force distribution of the wing plate support

[0140] The first part of the wing plate support 6 under the action of load and , , The wing plate support elastic foundation beam differential equation and initial parameter solution are

[0141]

[0142]

[0143] In the formula

[0144]

[0145] According to the integrated design requirements of the wing plate support 6 and the wing plate formwork, the first part of the wing plate support A 1 The end is elastically fixed, A n The end is free, then y ​0 =0, the initial parameter solution is

[0146]

[0147] In the above formula, substitute the formula two into the formula one , , the solution is , , , and

[0148]

[0149] The internal forces of the bottom flat bar 61, the inner inclined bar 62, the vertical bar 63, the middle inclined bar 64, the upper inclined bar 65, and the edge inclined bar 66 of the two-part wing plate support 6 can be obtained from the structural mechanics according to the formula one, the formula two, and the formula three. The strength and stiffness of each bar meet the strength and stiffness requirements of the used materials.

[0150] The definitions of the symbols in the formula one, the formula two, and the formula three are as follows:

[0151] —respectively the thickness of the root and the end of the cast-in-place box girder 3 wing plate, ;

[0152] —respectively the width at the starting end and the width at the end of the variable width section of the cast-in-place box girder 3 wing plate with a length of ; ;

[0153] —the calculation width of the cast-in-place box girder 3 wing plate as an elastic foundation beam model, i.e. the width of the upper inclined bar or the bottom flat bar, ;

[0154] —the equal interval between the inner inclined bar 62, the vertical bar 63, and the middle inclined bar 64 welded in each wing plate support 6, ;

[0155] —respectively the interval between each wing plate support 6 in the longitudinal direction of the cast-in-place box girder 3 wing plate, the length at the first segment centroid of the wing plate support 6 at the variable width end supported on the longitudinal bottom channel steel 4 and the transverse cross beam 51, the full length of the variable width section of the cast-in-place box girder 3 wing plate, and the length of the second segment cantilever part of the wing plate support 6 at the variable width end, ;

[0156] The height of the wing plate support at the centroid of the first section of the wing plate support 6 at the starting end of the widened end of the wing plate, the height of the wing plate support at the centroid of the first section of the wing plate support 6 at the ending end of the wing plate, the height of the wing plate support at the centroid of each section of the first section of the wing plate support 6, and the height of the wing plate support at the centroid of the second section of the wing plate support 6, ;

[0157] The horizontal value of the elastic foundation beam at the centroid of the starting end of the first section of the wing plate support 6, and the centroid of the wing plate support 6 is also used as the horizontal coordinate when calculating the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64, ;

[0158] The vertical deformation curve of the elastic foundation beam at the centroid of the starting end of the first section of the wing plate support 6, The centroid of the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64 of the wing plate support 6 is also used as the vertical coordinate when calculating the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64, ;

[0159] The inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64 of the wing plate support 6 are longitudinally coordinated with the outer diameter and the inner diameter of the steel pipe of the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64 of the wing plate support 6, ;

[0160] The outer diameter and the inner diameter of the steel pipe of the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64 of the wing plate support 6, ;

[0161] The outer diameter and the inner diameter of the steel pipe of the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64 of the wing plate support 6 are longitudinally coordinated with the outer diameter and the inner diameter of the steel pipe of the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64 of the wing plate support 6, ;

[0162] The length of the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64 of the wing plate support 6 supported on the longitudinal bottom groove steel 4 and the horizontal transverse beam 51 at the widened end of the wing plate support 6 is respectively The length of the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64 of the wing plate support 6 supported on the longitudinal bottom groove steel 4 and the horizontal transverse beam 51 at the widened end of the wing plate support 6 is respectively The number of sections of the inner inclined rod 62, the vertical rod 63 and the middle inclined rod 64 of the wing plate support 6,

[0163] The angle between the longitudinal axis of the inner inclined rod 62, the upper inclined rod 65 and the side inclined rod 66 of the wing plate support 6 and the horizontal line, ;

[0164] — The wing plate support 6 includes the inner inclined rod 62, the vertical rod 63 and the bottom flat rod 61 or the node number at the intersection with the edge inclined rod 66, the first section of the wing plate support 6 is numbered as 1, 2, 3, …, n from the starting end to the end, and the second section of the wing plate support 6 is numbered as 1, 2, 3, …, m from the starting end to the end.

[0165] — The unit weight of the cast-in-place box girder 3 wing plate reinforced concrete, ;

[0166] — The static load of the wing plate formwork 72 and the longitudinal square timber 52 and the dynamic load of the vibrating force of the vibrating cement concrete, ;

[0167] — The static load of the wing plate formwork 72 and the longitudinal square timber 52 and the dynamic load of the vibrating force of the vibrating cement concrete, The total weight of the cast-in-place box girder 3 wing plate reinforced concrete, the distributed load at the starting centroid of the wing plate support 6, the load at the end of the first section of the wing plate support 6, and the distributed load at the outermost end of the wing plate support 6, ;

[0168] — The reaction force of the longitudinal bottom groove steel 4 and the transverse horizontal timber 51 of the first section of the wing plate support 6 as an elastic foundation beam, which meets the Winkler assumption , ;

[0169] — The foundation reaction coefficient of the Winkler assumption, which can be obtained by referring to the relevant manual or through full support preloading test, ;

[0170] — The elastic foundation beam coefficient, , ;

[0171] — The elastic modulus of the groove steel and the steel pipe, ;

[0172] — The equivalent moment of inertia of the first section of the wing plate support 6 as an elastic foundation beam, ;

[0173] — The total moment of inertia of the upper inclined rod 65, the bottom flat rod 61, the vertical rod 63, and the inner inclined rod 62 and the middle inclined rod 64, respectively, ;

[0174] — inertia moment of single upper inclined bar 65, single bottom horizontal bar 61, single vertical bar 63, single inner inclined bar 62 and single middle inclined bar 64 respectively, ;

[0175] — inertia moment of single vertical bar 63 in the interval of 0~L / 2, inertia moment of single vertical bar 63 in the interval of L / 2~L respectively, ; ;

[0176] — inertia moment of single upper inclined bar 65 or single bottom horizontal bar 61 to its centroid x-axis when the notch is upward, inertia moment of single upper inclined bar 65 or single bottom horizontal bar 61 to its centroid x-axis when the notch is downward, cross-sectional area of single upper inclined bar 65 or single bottom horizontal bar 61 respectively, which can be found in the relevant material manual, ;

[0177] — upper inclined bar 65 tension and bottom horizontal bar 61 compression at the first segment end and the second segment start of slab support 6 at the end of the widening of the slab of cast-in-place box girder 3 respectively, ;

[0178] — moment of force at the first segment end and the second segment start of slab support 6 at the end of the widening of the slab of cast-in-place box girder 3, ;

[0179] — relevant parameters for the calculation of cast-in-place box girder 3 slab support as elastic foundation beam, dimensionless respectively;

[0180] — deflection, rotation angle, shear force and bending moment at the start of cast-in-place box girder 3 slab support as elastic foundation beam respectively, .

[0181] The construction method of the variable-width cast-in-place box girder formwork and slab support integrated structure mainly comprises the following steps:

[0182] Step 1: Determine the size of the variable-width cast-in-place box girder formwork and slab support integrated structure

[0183] 1. According to the actual situation of the variable-width cast-in-place box girder and the full-support frame, initially determine the size, arrangement form and engineering material selection of the variable-width cast-in-place box girder formwork and slab support integrated structure;

[0184] 2. Calculate and determine the size, arrangement form and engineering material selection of the variable-width cast-in-place box girder formwork and slab support integrated structure by formula 1, formula 2 and formula 3;

[0185] ​3. Prepare the construction organization design file and organize the construction;

[0186] Step two, erect full support and cast-in-place box girder form

[0187] 1. Select the materials for full support according to relevant standards and specifications, and design the structure of full support according to the design load;

[0188] 2. Measure and layout to determine the position, elevation and installation width of full support according to the design drawings;

[0189] 3. Full support erection process: support foundation acceptance → construction measurement positioning → installation of adjustable base to the designed height → installation of vertical rods and horizontal rods → installation of inclined rods → horizontal and vertical correction with level gauge → installation of vertical rods and horizontal rods in the previous step → installation of inclined rods → repeat the above steps until the designed height → measurement and positioning review → installation of adjustable top support to the designed height → preloading of full support load to meet the design requirements → installation of longitudinal base channel steel → installation of horizontal cross beams → laying of bottom formwork → installation of wing plate support → installation of diagonal bracing → installation of longitudinal beams → installation of wing plate formwork → hinge connection of wing plate support and wing plate formwork → installation of support rail → overall acceptance of full support, wing plate support, bottom formwork and wing plate formwork;

[0190] In order to strengthen the stability of the full support system, scissors are installed on the whole full support or connected with steel pipes around the bridge pier column. The displacement monitoring is strengthened through the pre-buried monitoring points during the installation and use of the full support system to ensure the safety of the support;

[0191] Step three, steel reinforcement binding and cement concrete pouring of cast-in-place box girder

[0192] 1. The steel reinforcement installation of cast-in-place box girder is divided into two stages. The first stage is to install the bottom plate and web steel reinforcement, and the second stage is to install the top plate steel reinforcement and wing plate steel reinforcement after the first concrete pouring. The steel reinforcement manufacturing and installation quality meets the design and standard specification requirements;

[0193] 2. After the installation of the web steel reinforcement of cast-in-place box girder, the prestressed pipe can be installed. This process is completed before the core form installation. The prestressed pipe, prestressed steel strand, anchor and clamp of cast-in-place box girder meet the national technical quality standards. The steel strand must not be exposed to rain during storage to prevent rust and contamination;

[0194] 3. The cast-in-place box girder concrete is poured in two times by pumping. The overall pouring sequence is first-time bottom plate and web concrete pouring → second-time top plate and flange plate concrete pouring. The interval time between the two times of pouring is not more than 10 days;

[0195] 4. The prestressed steel strand is batched for acceptance after leaving the factory. The quality certificate, packaging method and the contents of the label are checked for completeness and correctness. The tensile strength, elongation and other mechanical properties are tested according to the sampling standard. The anchorage device must have a factory certificate. Upon arrival, sampling is carried out according to the regulations, and appearance inspection and hardness testing are carried out. The steel strand is threaded into the hole one by one using a threading machine. The front of the steel strand should be fitted with a bullet-shaped shell cap. The threading machine controls the appropriate speed to push the steel strand into the hole;

[0196] 5. The cast-in-place box girder prestressed tension adopts intelligent tension construction technology. The system also sends instructions from the host according to the preset program to synchronously control each mechanical action of each device, automatically completing the entire tensioning process;

[0197] 6. The prestressed hole grouting adopts vacuum-assisted grouting technology. Strictly in accordance with the requirements of relevant standards and specifications, technical training is conducted for the operators before construction, and the construction is carried out strictly in accordance with the requirements of the specifications and guidelines to ensure the compactness and reliability of the grouting;

[0198] 7. After the hole grouting is completed, the anchor end cement slurry is flushed clean, the supporting pad is removed, the anchor device and the end face concrete are cleaned of dirt, and the end concrete is chipped. Set the anchor end reinforcement mesh, pour the anchor sealing concrete after fixing the sealing head formwork. The sealing concrete strength is the same as the main concrete strength grade. Carefully vibrate, pay attention to curing after demolding, and the anchor end layout should be strictly constructed according to the design drawings;

[0199] 8. Concrete curing: After the cement concrete is poured, the top surface of the cast-in-place box girder is roughened to a depth of 1mm to 2mm. The top surface is covered with plastic film + geotextile for moisture curing. Initial uninterrupted watering and spraying should not be less than 48h to prevent early shrinkage cracking of the concrete. After 48h, the concrete enters the regular curing period, which lasts for at least 7d;

[0200] Step four, cast-in-place box girder formwork and full-frame support removal

[0201] After all the prestressed construction is completed and the concrete strength and pipe grouting strength reach 100% of the design strength, the cast-in-place box girder formwork and full-frame support can be removed after the supervision engineer agrees;

[0202] 1. The principle of full-frame support 2 unloading is to complete it in a small amount, in batches and gradually, so that the cast-in-place box girder can gradually bear the load and avoid quality accidents during the unloading process;

[0203] 2. The full-frame support should be removed according to the principle of unloading the middle span first, then the rear span, the middle span first, and then the top of the pier. When unloading, it must be done in small amounts, slowly, symmetrically and uniformly. After checking that everything is correct, the amount of unloading can be gradually increased. It is not safe to unload a large amount at the beginning;

[0204] 3. Full-span scaffolding 2. Wing plate support 6. Bottom formwork 71. Wing plate formwork 72. During dismantling, the formwork should be slowly lowered to the ground. Do not throw it around to prevent damage. The formwork should be cleaned, repaired, sorted, and properly stored for reuse.

[0205] The above description is merely a specific embodiment of the present invention. Those skilled in the art should understand that any structural design equivalent to this embodiment should be included within the protection scope of the present invention.

Claims

1. An integrated structure for formwork and wing plate support of a variable-width cast-in-place box girder, comprising a full-span scaffold (2) erected on a foundation (1), characterized in that... The full-span scaffolding is topped with multiple longitudinal bottom channel steels (4) and transverse crossbeams (51) laid side by side, as well as multiple longitudinally spaced frame-type wing plate supports (6) and longitudinal crossbeams (52). A bottom template (71) is installed on the transverse crossbeams (51), and a wing plate template (72) is installed on the longitudinal crossbeams (52). Protective railings (8) are installed at the outer ends of the wing plate supports (6). Multiple cross-fixed diagonal braces (21) are provided between the multiple wing plate supports (6) and the full-span scaffolding (2). The flange support (6) is connected to the wing plate template (72) via a lower hinge (67) and an upper hinge (68); each wing plate support (6) is composed of a bottom flat bar (61), an inner diagonal bar (62), a vertical bar (63), a middle diagonal bar (64), and an upper diagonal bar (65) with the groove facing downward at the same width as the main line of the box girder; the bottom flat bar (61), the upper diagonal bar (65), and the side diagonal bar (66) are all made of channel steel, with the grooves of the bottom flat bar (61) and the side diagonal bar (66) facing upward, and the groove of the upper diagonal bar (65) facing downward; the inner The diagonal brace (62), vertical brace (63), and middle diagonal brace (64) are all steel pipes; the widening section of the main line of the box girder is a side diagonal brace (66) with the groove facing upward welded to the outer end of the bottom flat brace (61). The outer end of the side diagonal brace is fixed to the outer end of the upper diagonal brace (65). The upper diagonal brace extends inward and together with the inner diagonal brace (62), vertical brace (63), and middle diagonal brace (64) to form a variable-width wing plate support (6). On the variable-width wing plate support, longitudinal square timber (52) is laid in sequence and wing plate template (72) is installed; the wing plate support (6) is formed by the... The upper hinge (68) and lower hinge (67) at the beginning are connected to the hinge support of the cast-in-place box girder template to form an integrated structure; the lower hinge (67) and upper hinge (68) are both steel components, and one end of the lower hinge (67) or upper hinge (68) is embedded in the side of the wing plate template (72), and the other end is welded to the end of the inner diagonal bar (62) and the bottom flat bar (61) close to the wing plate template (72). The lower hinge (67) and upper hinge (68) are both connected by round steel, so that the wing plate template (72) or wing plate support (6) can rotate relative to each other.

2. The integrated structure of formwork and wing plate support for variable width cast-in-place box girder according to claim 1, characterized in that... The bottom flat bar (61) and the upper diagonal bar (65) are all welded firmly to the inner diagonal bar (62), the vertical bar (63), and the middle diagonal bar (64) to form a frame structure. The bottom flat bar (61) and the upper diagonal bar (65) are made of a single continuous channel steel. The total length of the widening section is... Width at the point of maximum widening The wing plate support (6) is divided into two sections: the first section consists of an upper diagonal rod (65), various inner diagonal rods (62), a vertical rod (63), a middle diagonal rod (64), and a bottom flat rod (61), with the length of the line connecting the vertical centroids being... It is considered as an elastic foundation beam supported on longitudinal bottom channel steel (4) and transverse cross timber (51), with upper diagonal bar (65) and bottom flat bar. Divide the length into equal parts The locations are the upper and lower endpoints of the inner diagonal brace (62), vertical brace (63), and middle diagonal brace (64), respectively; the second section The wing plate supporting the variable length section (6) is a cantilever frame structure, with the upper diagonal member (65) and the side diagonal members... Divide the length into equal parts The locations are the upper and lower ends of the vertical rod (63) and the middle diagonal rod (64), respectively; the load acting on the wing plate support (6) is divided into two parts: the first part is the sum of the static load of the self-weight of the wing plate formwork (72) and the longitudinal timber (52) and the dynamic load of the vibrating force of the cement concrete. The second part is the reinforced concrete widening self-weight load of the flange, and the thickness at the joint between the flange and the cast-in-place box girder (3) is... The thickness at the end of the wing is The length of the wing is The load on the wing plate supporting (6) is The load is distributed in a trapezoidal shape, with the maximum distributed load being... The minimum distributed load is The reaction forces of the longitudinal bottom channel steel (4) and the transverse cross timber (51) to the first wing plate support (6) conform to the Winkel hypothesis. The longitudinal spacing of each wing plate supporting (6) is Based on the theory of elastic foundation beams and structural mechanics, the following calculation formula is obtained: Formula 1: Calculate the load and moment of inertia With the average height of the centroids of the bottom flat bar (61) and the top diagonal bar (65) as the center line x-axis, and the centroids of the heights of the inner diagonal bars (62), vertical bars (63), and middle diagonal bars (64) as the y-axis, the calculated load of the wing plate support (6), the load of the elastic foundation beam supported on the longitudinal bottom channel steel (4) and the laid transverse cross timber (51), and the equivalent bending moment of inertia of the frame structure are: In the formula (1) The total moment of inertia of the upper inclined rod (65) about the x-axis The slot of the upper inclined rod (65) faces downward. Ignoring the influence of the slot inclination angle of the upper inclined rod (65) on its centroid, the moment of inertia about its centroid... I cgx下 Consult relevant data based on the channel steel's model and specifications; the area per unit length is... ,but (2) Total moment of inertia of the bottom flat bar (61) about the x-axis The slot of the upper diagonal bar (65) faces upward, and its moment of inertia about its centroid is... I sxgx上 Consult relevant materials according to the model and specifications of the channel steel. (3) Moment of inertia of a single vertical rod (63) about the x-axis and moment of inertia about the y-axis and the moment of inertia of the main vertical member about the x-axis Moment of inertia of a single vertical rod (63) about the y-axis (4) Moments of inertia of the inner diagonal member (62) and the upper diagonal member (65) about the x-axis The moment of inertia of a single inner diagonal bar (62) or upper diagonal bar (65) about the x-axis is caused by the rotation of the vertical bar (63) around the centroid. Angle calculation obtained Formula 2: Calculate the outer end of the first section supported by the wing plate. A n , B n Internal force at the location Disconnect the connection between the first part and the second part of the wing plate support (6). A n , B n ,have to Formula 3: Calculate the distribution of ground reaction force on the elastic foundation beam supported by the flange. The first part of the wing plate supports (6) under load. and , , Under the action of the flange supporting the elastic foundation beam, the differential equation and initial parameter solution are as follows: In the formula According to the integrated design requirements of the wing plate support (6) and the wing plate template, the first part of the wing plate support A 1 The end is elastically fixed. A n End freedom, then y 0 =0, the initial parameter solution is Substituting the above formula into Formula 2 , It can be solved , , ,have to Formulas 1, 2 and 3 can be used to calculate the internal forces of the bottom flat bar (61), inner diagonal bar (62), vertical bar (63), middle diagonal bar (64), upper diagonal bar (65) and side diagonal bar (66) of the two-part wing plate support (6) by structural mechanics. The strength and stiffness of each bar meet the strength and stiffness requirements of the materials used. The symbols in Formula 1, Formula 2, and Formula 3 are defined as follows: —These are the thicknesses of the root and end plates of the cast-in-place box girder (3), respectively. ; —The length of the widened section of the wing plate of the cast-in-place box girder (3) is respectively The width at the beginning and the widening end. ; —The calculated width of the wing plate of the cast-in-place box girder (3) as an elastic foundation beam model is the width of the upper diagonal bar or the bottom flat bar. ; —Equal intervals between the welded inner diagonal brace (62), vertical brace (63), and middle diagonal brace (64) of each wing plate support (6). ; — These are, respectively, the spacing between each longitudinal wing plate support (6) of the cast-in-place box girder (3), the length at the centroid of the first section of the wing plate support (6) at the widening end supported on the longitudinal bottom channel steel (4) and the transverse cross timber (51), the total length of the widening section of the cast-in-place box girder (3), and the length of the second cantilever section of the wing plate support (6) at the widening end. ; — These are the following: the wing plate support height at the end of the wing plate of the cast-in-place box girder (3), the wing plate support height at the centroid of the starting point of the first segment (6), the wing plate support height at the centroid of the end of the first segment (6), the wing plate support height at the centroid of each segment of the first segment (6), and the wing plate support height at the centroid of the end of the second segment (6). ; —The centroid of the first segment of the wing plate supporting (6) is used as the horizontal coordinate of the elastic foundation beam. When calculating the inner diagonal member (62), the vertical member (63) and the middle diagonal member (64), their centroids are also used as the horizontal coordinates. ; —The vertical coordinate value of the vertical deformation curve of the elastic foundation beam at the centroid of the first segment supported by the wing plate (6). When calculating the inner diagonal member (62), the vertical member (63), and the middle diagonal member (64), their centroids are also used as the vertical coordinates. ; —The centroids of the inner diagonal members (62), vertical members (63), and middle diagonal members (64) supporting the wing plate (6) are located at the longitudinal coordinates of the wing plate of the cast-in-place box girder (3). ; —The outer and inner diameters of the steel pipes for the inner diagonal brace (62), vertical brace (63), and middle diagonal brace (64) supporting the wing plate (6), respectively. ; —These are the longitudinal coordinates of the outer and inner diameters of the inner diagonal brace (62), vertical brace (63), and middle diagonal brace (64) of the cast-in-place box girder (3), respectively. ; —The spacing between the welded inner diagonal braces (62), vertical braces (63), and middle diagonal braces (64) at the centroid of the wing plate support (6) at the widened end of the longitudinal bottom channel steel (4) and the transverse cross timber (51) is as follows: The number of segments, the wing plate support at the widening end point (6), the length of the cantilever section, the distance between the welded vertical rod (63) and the middle diagonal rod (64) is The number of sections; —The wing plate support (6) includes the inner diagonal brace (62), the upper diagonal brace (65), and the side diagonal brace (66), and the angle between the longitudinal axis passing through the centroid and the horizontal line. ; —The wing plate support (6) includes the node numbers at the intersection of the inner diagonal bar (62), the vertical bar (63) and the bottom flat bar (61) or the side diagonal bar (66). The numbering from the beginning to the end of the first segment of the wing plate support (6) is 1, 2, 3, ..., n. The numbering from the beginning to the end of the second segment of the wing plate support (6) is 1, 2, 3, ..., m. —Unit weight of reinforced concrete for the wing plate of cast-in-place box girder (3), ; —The sum of the static load of the wing plate formwork (72) and the longitudinal timber (52) and the dynamic load of the vibrating force of the cement concrete, ; —The sum of the static load of the wing plate formwork (72) and the longitudinal timber (52) and the dynamic load of the vibrating force of the cement concrete, respectively. The total unit weight of the reinforced concrete of the wing plate of the cast-in-place box girder (3), the distributed load at the starting centroid of the wing plate support (6), the load at the end of the first section of the wing plate support (6), and the distributed load at the outermost end of the wing plate support (6) ; —The wing plate supports the reaction forces of the longitudinal bottom channel steel (4) and the transverse crossbeam (51) of the first section, which serves as an elastic foundation beam, in accordance with Winkel's hypothesis. , ; —The ground reaction coefficient assumed by Winkel can be obtained by consulting relevant manuals or through full-span scaffolding preloading tests. ; —Elastomeric foundation beam coefficient, , ; —The elastic modulus of channel steel and steel pipe, ; —The wing plate supports (6) the first segment as the equivalent moment of inertia of the elastic foundation beam. ; —The total moments of inertia of the upper diagonal member (65), the bottom flat member (61), the vertical member (63), including the inner diagonal member (62) and the middle diagonal member (64), respectively. ; —The moments of inertia of a single upper diagonal member (65), a bottom flat member (61), a vertical member (63), and including an inner diagonal member (62) and a middle diagonal member (64), respectively. ; —respectively, single vertical rods (63) in The moment of inertia of the interval, a single vertical rod (63) in Moment of inertia of the interval, ; —These are the moments of inertia about the centroid x-axis of a single upper inclined bar (65) or bottom flat bar (61) with the slot facing upwards, the moments of inertia about the centroid x-axis of a single upper inclined bar (65) or bottom flat bar (61) with the slot facing downwards, and the cross-sectional area of ​​a single upper inclined bar (65) or bottom flat bar (61), which can be obtained by consulting relevant material handbooks. ; —These are the tension of the upper diagonal brace (65) and the compressive force of the bottom flat brace (61) at the end of the first segment and the break between the first and second segments of the cast-in-place box girder (3), where the wing plate supports the widened end of the wing plate (6). ; — Cast-in-place box girder (3) Flange plate support at the end of the flange plate widening (6) Moment at the break between the end of the first section and the beginning of the second section, ; —These are the relevant parameters for calculating the cast-in-place box girder (3) wing plate supported as an elastic foundation beam, which are dimensionless; —The deflection, rotation, shear force, and bending moment at the starting end of the cast-in-place box girder (3) supported by the wing plate as an elastic foundation beam are calculated respectively. .

3. The integrated structure of formwork and wing plate support for variable width cast-in-place box girder according to claim 1, characterized in that... The two ends of the inner inclined rod (62) are welded to the bottom flat rod (61) and the upper inclined rod (65) to form a common node. The two ends of the vertical rod (63) and the middle inclined rod (64) are welded to the bottom flat rod (61) and the side inclined rod (66) to form a common node. The angle of inclination of the upper inclined rod (65) to the horizontal line is the same as the angle of inclination of the bottom surface of the wing plate template (72). The angle of inclination of the inner inclined rod (62) is the same as the angle of inclination of the side surface of the wing plate template (72). The slope of the middle inclined rod (64) is determined by the position of the two nodes mentioned above.

4. The integrated structure of formwork and wing plate support for variable width cast-in-place box girder according to claim 1, characterized in that... The bottom template (71) and wing template (72) are both steel components, which are supported on the transverse cross timber (51) and longitudinal cross timber (52) respectively and enclose the bottom plate, web plate and wing plate of the cast-in-place box girder (3).

5. The integrated structure of formwork and wing plate support for variable width cast-in-place box girder according to claim 1, characterized in that... The longitudinal bottom channel steel (4) is laid on top of the full-span support (2), and the transverse cross timber (51) is laid on the longitudinal bottom channel steel (4) as the base of the cast-in-place box girder formwork.

6. The integrated structure of formwork and wing plate support for variable width cast-in-place box girder according to claim 1, characterized in that... The longitudinal square timber (52) is a longitudinal square timber placed between each adjacent wing plate support (6).

7. The integrated structure of formwork and wing plate support for variable width cast-in-place box girder according to claim 1, characterized in that... The foundation (1) is the basis for erecting the full-span scaffolding (2); the cast-in-place box girder (3) is the superstructure of the viaduct; the widening section of the main line of the box girder is achieved by widening the wing plate template (72) to widen the cast-in-place box girder bridge deck.

8. The construction method of the integrated formwork and wing plate support structure for variable width cast-in-place box girder according to claim 1, characterized in that... The construction method includes the following steps: Step 1: Determine the integrated structural dimensions of the formwork and wing plate support for the variable width cast-in-place box girder.

1. Based on the actual situation of the variable width cast-in-place box girder (3) and the full-span support (2), the initial design of the integrated structure dimensions, layout and selection of engineering materials for the variable width cast-in-place box girder formwork and wing plate support (6) is proposed.

2. Calculate, verify and determine the integrated structure dimensions, layout and material selection of the formwork and wing plate support of the variable width cast-in-place box girder using Formula 1, Formula 2 and Formula 3; 3. Prepare construction organization design documents and organize construction; Step 2: Erect full-span scaffolding and cast-in-place box girder formwork.

1. Select the materials for the full-span scaffold (2) according to relevant standards and specifications, and design the structure of the full-span scaffold according to the design load; 2. Measure and lay out the layout, and determine the location, elevation, and installation width of the full-span scaffolding according to the design drawings; 3. Full-span scaffolding (2) erection process: scaffolding foundation acceptance → construction measurement and positioning → installation of adjustable base adjusted to design height → installation of uprights and horizontals → installation of diagonal braces → leveling with a spirit level to correct horizontality and verticality → installation of the previous uprights and horizontals → installation of diagonal braces → repeating the above steps until the design height → measurement and positioning verification → installation of adjustable top support adjusted to design height → full-span scaffolding load preloading meets design requirements → installation of longitudinal bottom channel steel → installation of transverse horizontal timber → laying of bottom formwork → installation of wing plate support → installation of diagonal braces → installation of longitudinal timber → installation of wing plate formwork → hinged connection between wing plate support and wing plate formwork → installation of scaffolding guardrails → overall acceptance of full-span scaffolding, wing plate support, bottom formwork, and wing plate formwork; To enhance the stability of the full-span scaffolding system, the entire full-span scaffolding system is equipped with scissor bracing or connected with steel pipes encircling the bridge piers. During the installation and use of the full-span scaffolding system, displacement monitoring is strengthened through pre-embedded monitoring points to ensure the safety of the scaffolding. Step 3: Reinforcement binding and cement concrete pouring of the cast-in-place box girder 1. The installation of cast-in-place box girder reinforcement is divided into two stages. The first stage is to install the bottom slab and web reinforcement first. The second stage is to install the top slab and wing plate reinforcement after the first concrete pour is completed. The quality of reinforcement fabrication and installation meets the design and standard specifications.

2. The prestressed ducts can be installed after the web reinforcement of the cast-in-place box girder is installed. This process is completed before the core mold is installed. The prestressed ducts, prestressed steel strands, anchors, and clamps of the cast-in-place box girder shall meet the national technical quality standards. The steel strands shall be kept away from rain during storage to prevent rust and shall not be contaminated with oil.

3. The cast-in-place box girder concrete is pumped and poured in two stages. The overall pouring sequence is: first pouring of bottom slab and web concrete → second pouring of top slab and flange concrete. The interval between the two pouring times shall not exceed 10 days.

4. After leaving the factory, prestressed steel strands are inspected in batches. During inspection, the quality certificate, packaging method and marking content are checked to ensure they are complete and correct. The tensile strength, elongation and other mechanical properties are tested according to the sampling standards. Anchorages must have a factory certificate. When they arrive on site, samples are taken according to regulations for visual inspection and hardness testing. Steel strands are inserted one by one using a stranding machine. A bullet-shaped cap should be placed on the front end of the steel strand. The strand is pushed into the channel by controlling the appropriate speed using the stranding machine.

5. The prestressing tensioning of the cast-in-place box girder adopts an intelligent tensioning construction process. The system also sends instructions from the host according to the preset program to synchronously control every mechanical action of each piece of equipment and automatically complete the entire tensioning process.

6. Vacuum-assisted grouting technology is used for prestressed duct grouting. It is carried out in strict accordance with relevant standards and specifications. Technical training is provided to operators before construction, and the construction is carried out in strict accordance with the specifications and guidelines to ensure the compactness and reliability of the grouting.

7. After the grouting of the duct is completed, the cement slurry at the anchor end is rinsed clean. At the same time, the support plate is removed, the dirt on the anchor and the end face concrete is cleaned, and the end concrete is roughened. The anchor end steel mesh is set, the end cap formwork is fixed, and the anchor sealing concrete is poured. The strength of the anchor sealing concrete is the same as the strength grade of the main concrete. It is vibrated carefully. After demolding, attention should be paid to curing. The anchor end arrangement should be strictly constructed according to the design drawings.

8. Concrete curing: After the cement concrete is poured, the top surface of the cast-in-place box girder is roughened. The roughening depth is controlled at 1mm to 2mm. The top surface is covered with plastic film and geotextile for moisture retention curing. Initially, continuous watering or spraying should be carried out for no less than 48 hours to prevent early shrinkage cracks in the concrete. After 48 hours, the concrete can enter the regular curing period, and the concrete curing time should not be less than 7 days. Step 4: Removal of formwork and scaffolding for cast-in-place box girder After all prestressed construction is completed and the concrete strength and grouting strength of the pipes reach 100% of the design strength, the formwork and full-span scaffolding of the cast-in-place box girder can be removed with the consent of the supervising engineer.

1. The principle of dismantling the full-span scaffolding is to complete it symmetrically, in small batches, and gradually, so that the cast-in-place box girder can gradually bear the load and avoid quality accidents in the structure during the dismantling process; 2. The dismantling of the full-span scaffolding should follow the principle of dismantling the middle span first and then the side spans, and the middle span first and then the top of the pier. The dismantling must be carried out in small amounts, slowly, symmetrically and evenly, and checked to ensure that there are no errors. Then the amount of dismantling should be gradually increased. It is absolutely forbidden to dismantle a large amount of scaffolding at the beginning, in order to ensure safety.

3. During the dismantling process, the full-span scaffold (2), wing plate support (6), bottom formwork (71), and wing plate formwork (72) should be slowly lowered to the ground. They should not be thrown around to prevent damage to the formwork. They should be cleaned, repaired, sorted, and properly stored for reuse.

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