A design method of cast-in-place beam form

Abstract

The present application relates to the technical field of beam body structure design construction, and particularly relates to a design method of cast-in-place beam formwork, which comprises a load calculation step of a bottom formwork and comprises the following steps: S1: respectively calculating dead load of the bottom formwork and live load of the bottom formwork, wherein the dead load of the bottom formwork comprises gravity of the bottom formwork, side formwork and reinforced concrete, and the live load of the bottom formwork comprises load generated by concrete vibration, load generated by personnel and construction; S2: calculating total load of the bottom formwork according to the dead load of the bottom formwork and the live load of the bottom formwork; S3: calculating stress and deflection of the bottom formwork according to the size of the bottom formwork; S4: judging whether the strength of the bottom formwork meets the requirements according to the stress and deflection of the bottom formwork. The method can obtain the design parameters of the bottom formwork which just meet the strength requirements through calculation, can guarantee that the bottom formwork meets the strength requirements while using the least amount of steel structure, reduces construction workload, improves construction efficiency, and additionally reduces the self weight of the formwork structure, facilitates demolding after pouring.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of beam structure design and construction, in particular to a design method of cast-in-place beam formwork. BACKGROUND

[0002] For the beam structure of cast-in-place beam, especially the cast-in-place beam structure in the port area, generally, the concrete beam section is supported by multiple steel pipe piles, and a formwork including a bottom formwork, a side formwork and the like needs to be erected on the steel pipe piles before pouring. The bottom formwork needs to be erected between two adjacent steel pipe piles through a horizontal and vertical beam structure to form a certain span, and the bottom formwork needs to bear the vertical loads of the upper side formwork, concrete, steel bars, personnel and equipment during pouring. The side formwork also needs to bear the horizontal loads generated by concrete vibration, so the bottom formwork and the side formwork need to have sufficient strength for support. At present, in the design of cast-in-place beam formwork, especially for the size of the cast-in-place beam formwork, the number and spacing of I-beams and channel steel structures erected on the horizontal and vertical beams and other parameters, there is a lack of effective calculation method to verify whether the strength of the formwork meets the use requirements. Only the experience of on-site construction personnel can be relied on for selection. In order to ensure the stability of the beam structure and avoid safety hazards, as many I-beams and channel steels as possible are often arranged in the horizontal and vertical beam structure of the bottom formwork to improve the support performance. However, too many steel structures will increase the construction workload and reduce the construction efficiency, and in addition, they will also increase the self-weight of the formwork structure, causing inconvenience to the demolding after pouring. SUMMARY

[0003] The present application aims to overcome the technical problem that the design of the cast-in-place beam formwork relying on experience in the prior art will result in too many steel structures in the formwork, thereby causing low construction efficiency, and provides a design method of cast-in-place beam formwork.

[0004] The present application provides a design method of cast-in-place beam formwork, the cast-in-place beam formwork comprising a bottom formwork and a side formwork, the bottom formwork being horizontally erected between a plurality of steel pipe piles, and the side formwork being vertically installed on the bottom formwork; the design method comprising a load calculation step of the bottom formwork, comprising: S1: calculating the dead load of the bottom formwork and the live load of the bottom formwork respectively, the dead load of the bottom formwork comprising the gravity of the bottom formwork, the gravity of the side formwork and the gravity of the reinforced concrete, and the live load of the bottom formwork comprising the load generated by concrete vibration, the load generated by personnel and construction; S2: calculating the total load of the bottom formwork according to the dead load of the bottom formwork and the live load of the bottom formwork; S3: calculating the stress and deflection of the bottom formwork according to the size of the bottom formwork; S4: judging whether the strength of the bottom formwork meets the requirements according to the stress and deflection of the bottom formwork.

[0005] The design method of the present application can divide the load borne by the bottom formwork into constant load and live load for checking respectively, can obtain the total load borne by the bottom formwork in the construction process, can further calculate the stress and deflection parameters of the bottom formwork, and then compare the calculated stress and deflection parameters with the parameter values specified in the construction specification standard, if less than the standard value, it meets the strength requirement, if greater than the standard value, it is necessary to further adjust the size of the steel structure in the bottom formwork until it meets the requirements after rechecking; the design method can obtain the bottom formwork design parameters that just meet the strength requirements through calculation, which can ensure that the bottom formwork meets the strength requirements while using the least amount of steel structure, reduces the construction workload, improves the construction efficiency, and also reduces the self-weight of the formwork structure, facilitating stripping after pouring.

[0006] Preferably, the bottom formwork comprises a transverse beam bottom formwork and a longitudinal beam bottom formwork perpendicular to each other, the transverse beam bottom formwork is arranged on the longitudinal beam bottom formwork, and the transverse beam bottom formwork and the longitudinal beam bottom formwork each comprise a clamping plate, a plurality of secondary beams and a plurality of main beams; the design method comprises a load calculation step of the transverse beam bottom formwork and the longitudinal beam bottom formwork, comprising: A1: calculating the constant load of the clamping plate, the secondary beam or the main beam, and calculating the live load of the clamping plate, the secondary beam or the main beam; A2: calculating the total load of the clamping plate, the secondary beam or the main beam according to the constant load and the live load of the clamping plate, the secondary beam or the main beam; A3: calculating the stress and deflection of the clamping plate, the secondary beam or the main beam according to the size of the clamping plate, the secondary beam or the main beam; A4: judging whether the strength of the clamping plate, the secondary beam or the main beam meets the requirements according to the stress and deflection of the clamping plate, the secondary beam or the main beam.

[0007] The transverse beam bottom formwork and the longitudinal beam bottom formwork are modularized designs, and each component in the transverse beam bottom formwork and the longitudinal beam bottom formwork can be checked respectively to verify whether the stress and deflection parameters borne meet the strength requirements, if not, the spacing and quantity of the clamping plate, the secondary beam and the main beam in the transverse beam bottom formwork and the longitudinal beam bottom formwork need to be adjusted, and then rechecked until the requirements are met.

[0008] Preferably, the plurality of main beams are connected by welding or bolt fixing, and the plurality of secondary beams are connected on the main beams by welding or bolt fixing; the plurality of main beams are located in a first plane, and the plurality of secondary beams are located in a second plane, and the first plane and the second plane are parallel and arranged in a spaced manner.

[0009] Specifically, for example, in the beam bottom die, including 6 main beams and 14 secondary beams, wherein 4 main beams are arranged transversely and parallel to each other, and the other 2 main beams are arranged longitudinally and connected at both ends of the 4 transversely arranged main beams, that is, the 4 transversely arranged main beams can be connected by the 2 longitudinally arranged main beams, and the 6 main beams can be connected to form a whole; 14 secondary beams can be arranged longitudinally and parallel to each other, and the 14 secondary beams can be connected to the 4 transversely arranged main beams, and the 14 secondary beams and the 6 main beams can form a whole structure, and the main beams and the main beams, and the main beams and the secondary beams can be fixedly connected by welding or bolt connection, etc. The formwork plate can be formed into a modular structure, and the strength design calculation of the single modular formwork plate can be completed before the overall construction of the formwork, and the whole can be disassembled by cutting the corbels on the steel pipe pile when demolding after pouring. Since the existing scattered formwork structure has no fixing measures for the I-beams and channel steels, the modular formwork structure of the present application avoids the problem of reducing the construction efficiency caused by separately erecting and disassembling the I-beams and channel steels during construction, and is more convenient and efficient for construction, reduces the material loss rate, and at the same time, the modular formwork structure is more conducive to repeated use after disassembly.

[0010] In addition, the modular formwork structure of the present application can fix multiple I-beams in the same plane and multiple channel steels in another parallel plane by welding, so that the formwork structure is two-layered, while the scattered formwork structure has no fixing measures, and the transversely arranged I-beams need to be erected on the longitudinally arranged I-beams, so that the scattered formwork structure is at least three-layered. Therefore, the modular formwork structure of the present application reduces the existing three-layer structure to two layers, and the thickness of the formwork can be further reduced. For example, if the main beam is a 25# I-beam, the thickness of the formwork can be reduced by about 25 cm after reducing one layer of the formwork structure. In construction, the top elevation of the formwork is fixed, that is, the upper surface height of the formwork needs to meet the construction standard, and the lower surface of the formwork needs to be erected on the corbel of the steel pipe pile. If the thickness of the formwork is too large, it means that the height of the corbel is lower, and the position of the corbel is more likely to be below the water surface during high tide, which is not conducive to the welding construction of the corbel and may cause the construction window period of the corbel to be shortened, which may lead to a prolonged construction period and reduced efficiency. After reducing the three-layer structure of the formwork to two layers, the thickness of the formwork can be significantly reduced, which can raise the position of the corbel on the steel pipe pile, reduce the possibility of the corbel being below the water surface, extend the construction window period of the corbel, and improve the construction efficiency of the corbel.

[0011] Preferably, the design method further comprises a load calculation step of the side formwork, comprising: B1: calculating the maximum lateral pressure F generated by concrete vibration on the side formwork and the horizontal load F' generated by pouring concrete; B2: calculating the total load of the side formwork according to the maximum lateral pressure F generated by concrete vibration on the side formwork and the horizontal load F' generated by pouring concrete.

[0012] Preferably, the calculation formula of the maximum lateral pressure F is:

[0013]

[0014] and

[0015] F = γ c H (2)

[0016] The maximum lateral pressure F takes the smaller value in formula (1) and formula (2).

[0017] Preferably, the horizontal load F' generated by pouring concrete takes a maximum value of 6kN / m 2 .

[0018] Preferably, calculating the total load of the side formwork comprises calculating the standard value q' of lateral pressure and the design value q of lateral pressure respectively, q' = F + F'; q = F × dead load partial coefficient + F' × live load partial coefficient; the dead load partial coefficient takes 1.2, and the live load partial coefficient takes 1.4.

[0019] The main stress types of the side formwork can be divided into lateral pressure generated by concrete vibration and horizontal load generated by pouring concrete, the lateral pressure generated by concrete vibration can be checked by the corresponding calculation formula, and the horizontal load generated by pouring concrete can refer to the standard value in the relevant specification.

[0020] Preferably, the side formwork comprises a clamping plate and a plurality of channel steels, and the load calculation step of the side formwork further comprises: C1: calculating the stress and deflection of the clamping plate and the stress and deflection of the channel steels respectively; C2: judging whether the stress and deflection of the clamping plate and the channel steels meet the requirements.

[0021] Preferably, the calculation formula of the stress σ of the clamping plate and the channel steels is: σ = M / W; in the formula, M is the bending strength, and W is the section parameter.

[0022] Preferably, the calculation formula of the deflection ω of the clamping plate and the channel steels is: ω = (Ml^2) / 9.6EI; in the formula, M is the bending strength, l is the maximum span size of the clamping plate or the channel steels, E is the elastic modulus of the clamping plate or the channel steels, and I is the section moment of inertia of the clamping plate or the channel steels.

[0023] The side form plate is mainly composed of channel steel and clamping plates, stress parameters of the channel steel and the clamping plates can be respectively calculated by corresponding calculation formula, and compared with related standard values to determine whether the requirements are met, if not, the spacing and quantity of the clamping plates and the channel steel in the side form plate need to be adjusted, and then recalculate until the requirements are met.

[0024] Preferably, a plurality of corbels are arranged on the steel pipe pile, and the bottom form plate is arranged on the corbels; the design method further comprises a load calculation step of the corbels, comprising: D1: calculating bending stress and shear stress parameters of the corbels respectively; D2: judging whether the strength of the corbels meets the requirements according to the bending stress and the shear stress parameters of the corbels.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] 1. The present application provides a design method of cast-in-place beam formwork, which can divide the load borne by the bottom form plate into dead load and live load for separate checking, obtain the total load borne by the bottom form plate during construction, further calculate the stress and deflection parameters of the bottom form plate, and compare the calculated stress and deflection parameters with the parameter values specified in the construction specification standard, if the calculated values are less than the standard values, the strength requirements are met, if the calculated values are greater than the standard values, the size of the steel structure in the bottom form plate needs to be further adjusted until the checking results meet the requirements after adjustment; the design method can obtain the design parameters of the bottom form plate that just meet the strength requirements, ensure that the bottom form plate meets the strength requirements while using the least amount of steel structure, reduce the construction workload, improve the construction efficiency, and further reduce the self-weight of the formwork structure and facilitate stripping after pouring.

[0027] 2. The present application provides a formwork structure of cast-in-place beam, which can form a modular overall structure by welding or bolt connection between the main beams, between the secondary beams and the main beams, and can perform strength design checking and assembly on a single modular formwork before overall construction of the formwork, and can be disassembled as a whole by cutting the corbels on the steel pipe pile when stripping after pouring, thereby improving the construction efficiency and reducing the material loss rate; in addition, the existing three-layer formwork structure can be reduced to a two-layer structure, which can significantly reduce the thickness of the formwork, and further raise the position of the corbels on the steel pipe pile, reduce the possibility of the corbels being below the water surface, prolong the construction window period of the corbels, and improve the construction efficiency of the corbels. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 FIG. 1 is a plan view of the bottom form plate.

[0029] Figure 2 FIG. 4 is a plan view of the bottom form of the cross beam.

[0030] Figure 3Fig. 4 is a schematic view of a cross section of the beam base mould.

[0031] Figure 4 Fig. 5 is a schematic view of an elevation assembly of the beam base mould.

[0032] Figure 5 Fig. 6 is a schematic view of a plan of the stringer base mould.

[0033] Figure 6 Fig. 7 is a schematic view of a cross section of the stringer base mould.

[0034] Figure 7 Fig. 8 is a schematic view of an elevation assembly of the stringer base mould.

[0035] Figure 8 Fig. 9 is a schematic view of a back elevation of the side mould plate.

[0036] Figure 9 Fig. 10 is a schematic view of a plan of the corbel position.

[0037] Fig. 11 is a schematic view of a plan of the steel pipe pile.

[0038] 1, steel pipe pile, 2, base mould plate, 21, beam base mould, 22, stringer base mould, 23, clamping plate, 24, secondary beam, 25, main beam, 3, side mould plate, 31, 12# channel steel, 4, corbel. DETAILED DESCRIPTION

[0039] The application will be described in further detail below with specific embodiments. However, it should not be understood that the above-mentioned subject matter of the application is limited to the following embodiments only, and any technology realized based on the content of the application falls within the scope of the application.

[0040] In the description of the specific embodiments of the application, the orientation or position relationship terms such as "up", "down", "left", "right", "center", "inner", "outer" and the like are expressed based on the orientation or position relationship shown in the drawings, or the orientation or position relationship when the product / equipment / device of the application is usually used. These orientation or position relationship terms are only for the convenience of describing the application scheme or simplifying the description in the specific embodiments, and for the convenience of the technical personnel to quickly understand the scheme, and are not intended to indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the application.

[0041] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding device / component / element is required to be absolutely horizontal or vertical or overhanging or parallel, but can be slightly inclined or deviated. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. Alternatively, it can be simplified to understand that the corresponding device / component / element is arranged in the direction of "horizontal", "vertical", "overhanging", "parallel" and the like, and can have an error / deviation of ±10% relative to the corresponding direction, more preferably an error / deviation of ±8% or less, more preferably an error / deviation of ±6% or less, more preferably an error / deviation of ±5% or less, more preferably an error / deviation of ±4% or less. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the present application.

[0042] In addition, the terms "first", "second", "third" and the like in the terms are only used to distinguish the same or similar components for description, and should not be understood as emphasizing or implying the relative importance of the specific components.

[0043] In addition, in the description of the embodiments of the present application, "several", "a plurality of", "several" represent at least 2. It can be 2, 3, 4, 5, 6, 7, 8, 9, etc. Any case, it can even be more than 9 cases.

[0044] In addition, in the description of the technical solutions of the present application, unless otherwise specified / limited / limited, the terms "arrangement", "installation", "connection", "connection", "provided with", "laid", "arrangement" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, which can be welding, riveting, bolting, screwing and other commonly used connection means in the art. The connection can be mechanical connection, electrical connection or communication connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between two elements.

[0045] Embodiment

[0046] The present embodiment provides a design method of cast-in-place beam formwork.

[0047] As Figures 1 to 9The structure and position of the bottom die plate 2, the cross beam bottom die 21, the longitudinal beam bottom die 22, the side die plate 3 and the bracket 4 are shown in the figure, wherein the cross beam bottom die 21 and the longitudinal beam bottom die 22 are arranged in a longitudinal and transverse staggered manner between the plurality of steel pipe piles 1 to form the overall structure of the bottom die plate 2, specifically, the longitudinal beam bottom die 22 is arranged on the bracket 4 of the steel pipe pile 1, and the cross beam bottom die 21 is arranged on the longitudinal beam bottom die 22; the bottom die plate 2 is arranged horizontally, and the side die plate 3 is vertically arranged above the bottom die plate 2; the cross beam bottom die 21 and the longitudinal beam bottom die 22 each include a clamping plate 23, a plurality of secondary beams 24 and a plurality of main beams 25, wherein the secondary beam 24 can be an 8# channel steel, the main beam 25 can be a 25# I-beam, and the side die plate 3 includes a clamping plate 23 and a 12# channel steel 31.

[0048] Specifically, the cross beam bottom die 21 can include 6 main beams 25 and 14 secondary beams 24, wherein 4 main beams 25 are arranged transversely and parallel to each other, and the other 2 main beams 25 are arranged longitudinally and connected at both ends of the 4 main beams 25 arranged transversely, that is, the 4 main beams 25 arranged transversely can be connected by the 2 main beams 25 arranged longitudinally, and the 6 main beams 25 can be connected to form an integral whole; the 14 secondary beams 24 can be arranged longitudinally and parallel to each other, and the 14 secondary beams 24 can be connected to the 4 main beams 25 arranged transversely, and the 14 secondary beams 24 and the 6 main beams 25 can be connected to form an integral structure; the main beams 25 and the secondary beams 24 can be fixedly connected by welding or bolting, etc., so as to form a modular structure of the bottom die plate; the longitudinal beam bottom die 22 can include 6 main beams 25 and 15 secondary beams 24, of course, the number of the main beams 25 and the secondary beams 24 in the cross beam bottom die 21 and the longitudinal beam bottom die 22 needs to be determined according to the design calculation results, and the number of the main beams 25 and the secondary beams 24 may change under different working conditions, and the present application does not specifically limit the number of the main beams 25 and the secondary beams 24 in the bottom die.

[0049] In addition, the 6 main beams 25 in the cross beam bottom die 21 are located on a first plane, and the 14 secondary beams 24 are located on a second plane, and the first plane and the second plane are arranged in parallel and spaced apart from each other, that is, the first plane and the second plane do not coincide (are not coplanar), so that the cross beam bottom die 21 forms a two-layer structure, and by analogy, the 6 main beams 25 and the 15 secondary beams 24 in the longitudinal beam bottom die 22 are also located on different planes to form a two-layer structure; compared with the three-layer structure of the existing scattered formwork, the two-layer structure formwork can further reduce the thickness size, so as to raise the position of the bracket on the steel pipe pile, reduce the possibility that the position of the bracket is lower than the water surface, prolong the construction window period of the bracket, and improve the construction efficiency of the bracket.

[0050] The design method is used for design calculation taking the formwork structure in the figure as an example, wherein the numerical values calculated by the formula only represent one kind of size and quality value of the formwork, and the scope of protection of the present application is not limited to a certain specific numerical value.

[0051] The vertical load in construction mainly includes:

[0052] Dead load: self-weight of formwork (bottom form, side form, pouring platform plate), self-weight of newly poured concrete (the first pouring height of track beam is 2.15 meters; the pouring height of longitudinal beam is 1.55 meters, 1.65 meters; the size of cross beam is 1.4-2.0 meters, and the self-weight of concrete is selected as the self-weight of concrete with pouring height of 1.65 meters; the first pouring height of track beam on the side of the pier involves cantilever structure, which is 2.15 meters);

[0053] Live load: load of construction personnel and equipment, load (vertical direction) generated by vibrating concrete.

[0054] The horizontal load in construction includes: load generated by vibrating concrete.

[0055] Coefficient value: the sub-item coefficient of dead load is 1.2; the sub-item coefficient of live load is 1.4.

[0056] Formwork size (unit: mm), formwork size (length x width) is: the size of middle longitudinal beam bottom form 22 plate 2 is 5100 x 1800; the size of cross beam bottom form 21 is 4700 x 1800, 4148 x 1800; the size of side form is 4380 x 1780, 3930 x 1780, 3430 x 1780, 4380 x 2250.

[0057] The calculation method of cross beam bottom form 21 is as follows:

[0058] The main beam 25 of cross beam bottom form 21 adopts 25# I-beam, the middle distance is 470 mm, a total of 4, the secondary beam 24 adopts 8# channel steel, the distance is 310 mm, a total of 14, all of which are processed with new materials, holes are opened on the 8# channel steel, 50*30 mm wooden strips are fixed on the 8# channel steel with bolts, and 18 mm thick clamps 23 are nailed on the wooden strips; the cross beam bottom form 21 has two sizes, the formwork with the largest span is taken for checking and calculating, so the cross beam bottom form 21 with the size of 4700 x 1800 is taken for checking and calculating.

[0059] Clamp 23 dead load calculation:

[0060] Self-weight of bottom form clamp: 83 x 10 / 1000 = 0.83 KN;

[0061] Self-weight of side form: 500 x 10 x 2 / 1000 = 10 KN;

[0062] Self-weight of pouring platform plate:

[0063] Self-weight of reinforced concrete: 6.0 x 1.4 x 1.65 x 2500 x 10 / 1000 = 346.5 KN;

[0064] The total dead load standard value is: G = 360.33 KN;

[0065] The total dead load design value is: G = 360.33 x 1.2 = 432.4 KN;

[0066] The dead load surface load design value is:

[0067] The live load calculation of the clamping plate 23:

[0068] The load generated by vibrating concrete: 2 kN / m 2 ;

[0069] The human and construction load is: 2.5 kN / m 2

[0070] The total live load standard value is: 4.5 kN / m 2 ;

[0071] The total live load design value is: 4.5 x 1.4 = 6.3 kN / m 2 ;

[0072] The force combination of the clamping plate 23

[0073] Select 1 cm clamping plate as the calculation unit, and the linear uniform load design value is:

[0074] q = 0.01 x (65.72 + 6.3) = 0.72 N / mm;

[0075] The force calculation of the clamping plate 23

[0076] The plate surface calculation specification stipulates that when the plate surface has only horizontal ribs without small longitudinal ribs, the panel is a one-way panel, and a grid on the panel can be taken as the calculation unit. One-way plate mainly bends in one direction, and the ratio of long side to short side is greater than or equal to 2, so the bending moment in the long span direction can be ignored, and it is approximately considered that the force is only transmitted to the long side along the short span direction., this structure is approximately considered as a simply supported structure, so it can be approximately considered that the maximum span of the clamping plate is 310 mm, and the thickness is 1.8 cm; select 1 cm as the calculation unit:

[0077] The section parameters of the clamping plate 23 are:

[0078] The section moment of inertia of the clamping plate 23 is:

[0079] The bending strength check of the clamping plate 23:

[0080] The formwork stress of the clamping plate 23 under bending state is:

[0081] Satisfies the requirements.

[0082] Clamp plate 23 deflection test:

[0083] Requirements are met.

[0084] Secondary beam 24 constant load calculation

[0085] The self-weight of the bottom mold clamp plate is 83x10 / 1000=0.83KN;

[0086] The self-weight of the bottom mold batten is 25x10 / 1000=0.25KN;

[0087] The self-weight of the side mold plate is 500x10x2 / 1000=10KN;

[0088] The self-weight of the pouring platform plate is:

[0089] The self-weight of the reinforced concrete is 6.0x1.4x1.65x2500x10 / 1000=346.5KN;

[0090] The total constant load standard value is G=360.58KN;

[0091] The total constant load design value is G=360.58x1.2=432.7KN;

[0092] The constant load surface load design value is:

[0093] Secondary beam 24 live load calculation

[0094] The load generated by vibrating concrete is 2kN / m 2 ;

[0095] The human and construction load is 2.5kN / m 2

[0096] The total live load standard value is 4.5kN / m 2 ;

[0097] The total live load design value is 4.5x1.4=6.3kN / m 2 ;

[0098] Force combination of secondary beam 24

[0099] The unit weight of 8# groove is 8.045kg / m, so the self-weight is 0.46x8.045x10 / 1000=0.1KN / m, and the uniform load design value is q=0.46x(65.76+6.3)+0.1=33.25N / mm;

[0100] Secondary beam 24 force calculation

[0101] The maximum distance of the secondary beam 24 is 310 mm, and the span is: l=460 mm:

[0102] The two 8# channel sections have the following characteristics: W=2×25.3×10 3 mm 3 ; I=2×101×10 4 mm 4 ;

[0103] The maximum bending moment of three spans is calculated as approximately continuous beam:

[0104] M=0.1ql 2 =0.1×33.25×460 2 =703570 N·mm

[0105] Strength checking of the secondary beam 24: Satisfies the requirements.

[0106] Deflection checking of the secondary beam 24:

[0107] Satisfies the requirements.

[0108] Dead load calculation of the main beam 25

[0109] Self weight of the bottom mold clamping plate: 83×10 / 1000=0.83 KN;

[0110] Self weight of the bottom mold timber: 25×10 / 1000=0.25 KN;

[0111] Self weight of the bottom mold 8# channel: 36.24×8.045×10 / 1000=2.92 KN;

[0112] Self weight of the side mold plate: 500×10×2 / 1000=10 KN;

[0113] Self weight of the pouring platform plate:

[0114] Self weight of the reinforced concrete: 6.0×1.4×1.65×2500×10 / 1000=346.5 KN;

[0115] The total dead load standard value is: G=363.5 KN;

[0116] The total dead load design value is: G=363.5×1.2=436.2 KN;

[0117] The dead load surface load design value is:

[0118] Live load calculation of the main beam 25

[0119] Load generated by vibrating concrete: 2 kN / m2 ;

[0120] The human and construction load is: 2.5kN / m 2

[0121] The total live load standard value is: 4.5kN / m 2 ;

[0122] The total live load design value is: 4.5x1.4 = 6.3kN / m 2 ;

[0123] The force combination of the main beam 25

[0124] The unit weight of the 25# I-beam is 42.03kg / m, so the self weight of the 25# I-beam is:

[0125] 4.7x42.03x10 / 1000 = 1.97KN / m;

[0126] The design value of the uniform load is: q = 1.4x(66.29 + 6.3) + 1.97 = 103.6N / mm;

[0127] The force calculation of the main beam 25

[0128] The maximum spacing of the main beam 25 is 460mm, the span is: l = 4700mm, and the load is approximately uniformly distributed load through the 8# channel steel to the 25# I-beam:

[0129] The section parameters of the 4 25a I-beams are: W = 4x402x10 3 mm 3 ; I = 4x5020x10 4 mm 4 ;

[0130] The maximum bending moment is calculated as approximately continuous beam for three spans:

[0131] M = 0.1ql 2 = 0.1x103.6x4700 2 = 228.85x10 6 N·mm

[0132] The strength check of the main beam 25: Satisfies the requirements;

[0133] The deflection check of the main beam 25:

[0134] Satisfies the requirements;

[0135] The calculation method of the longitudinal beam bottom die 22 is as follows:

[0136] The main beam of the longitudinal beam base mould 22 is made of 25# H-shaped steel, and the middle distance is 470mm, and there are 4 strips in total. The secondary beam is made of 8# channel steel, and the distance is 315mm, and there are 15 strips in total. All are processed with new materials, and holes are opened on the 8# channel steel. The 50*30mm wood strip is fixed on the 8# channel steel by bolts, and the 18mm thick clamping plate is nailed on the wood strip. The longitudinal beam base mould has two sizes, and the largest span mould is taken for checking, so the 5100*1800 longitudinal beam base mould is taken for checking.

[0137] The dead load calculation of the clamping plate 23

[0138] The self weight of the base mould clamping plate is 88*10 / 1000=0.88KN;

[0139] The self weight of the side mould plate is 500*10*2 / 1000=10KN;

[0140] The self weight of the pouring platform plate is:

[0141] The self weight of the reinforced concrete is 6.4*1.4*1.65*2500*10 / 1000=369.6KN;

[0142] The total dead load standard value is G=383.48KN;

[0143] The total dead load design value is G=383.48*1.2=460.18KN;

[0144] The dead load surface load design value is:

[0145] The live load calculation of the clamping plate 23

[0146] The load generated by vibrating concrete is 2kN / m 2 ;

[0147] The human and construction load is 2.5kN / m 2

[0148] The total live load standard value is 4.5kN / m 2 ;

[0149] The total live load design value is 4.5*1.4=6.3kN / m 2 ;

[0150] The force combination of the clamping plate 23

[0151] Select 1cm clamping plate as the calculation unit, and the linear uniform load design value is:

[0152] q=0.01*(64.45+6.3)=0.71N / mm;

[0153] The force calculation of the clamping plate 23

[0154] From the figure, the structural panel is a one-way board, so it can be approximately considered that the maximum span of the clamping plate is 315 mm and the thickness is 1.8 cm; select 1 cm clamping plate as the calculation unit:

[0155] The section parameters of the clamping plate 23 are:

[0156] The bending strength of the clamping plate 23 is checked:

[0157] The formwork stress of the clamping plate 23 under bending state is:

[0158] It meets the requirements.

[0159] The deflection of the clamping plate 23 is checked:

[0160] It meets the requirements.

[0161] Calculation of secondary beam 24 dead load

[0162] The self weight of the bottom mold clamping plate is: 88x10 / 1000=0.88KN;

[0163] The self weight of the bottom mold timber is: 20x10 / 1000=0.2KN;

[0164] The self weight of the side mold plate is: 500x10x2 / 1000=10KN;

[0165] The self weight of the pouring platform plate is:

[0166] The self weight of the reinforced concrete is: 6.4x1.4x1.65x2500x10 / 1000=369.6KN;

[0167] The total dead load standard value is: G=383.68KN;

[0168] The total dead load design value is: G=383.68x1.2=460.42KN;

[0169] The dead load surface load design value is:

[0170] Calculation of secondary beam 24 live load

[0171] The load generated by vibrating concrete is: 2kN / m 2 ;

[0172] The human and construction load is: 2.5kN / m 2

[0173] The total live load standard value is: 4.5kN / m 2 ;

[0174] Total live load design value: 4.5 x 1.4 = 6.3 kN / m 2 ;

[0175] Force combination of secondary beam 24

[0176] 8# channel unit weight 8.045 kg / m, so the dead weight is 0.46 x 8.045 x 10 / 1000 = 0.1 KN / m, design value of uniform load: q = 0.46 x (64.48 + 6.3) + 0.1 = 32.66 N / mm;

[0177] Force calculation of secondary beam 24

[0178] The maximum spacing of secondary beam 24 is 315 mm, and the span is: l = 460 mm

[0179] 8# channel section parameters: W = 2 x 25.3 x 10 3 mm 3 ; I = 2 x 101 x 10 4 mm 4 ;

[0180] Take three spans as approximate continuous beam to calculate the maximum bending moment:

[0181] M = 0.1ql 2 = 0.1 x 32.66 x 460 2 = 691085.6 N·mm

[0182] Strength checking of secondary beam 24: Satisfies the requirement;

[0183] Deflection checking of secondary beam 24:

[0184] Satisfies the requirement; Main beam 25 constant load calculation

[0185] Dead weight of bottom mold clamping plate: 88 x 10 / 1000 = 0.88 KN;

[0186] Dead weight of bottom mold timber: 20 x 10 / 1000 = 0.2 KN;

[0187] Dead weight of bottom mold 8# channel: 338 x 10 / 1000 = 3.38 KN;

[0188] Dead weight of side mold plate: 500 x 10 x 2 / 1000 = 10 KN;

[0189] Dead weight of pouring platform plate:

[0190] Dead weight of reinforced concrete: 6.4 x 1.4 x 1.65 x 2500 x 10 / 1000 = 369.6 KN;

[0191] The total dead load standard value is: G = 387.06 KN;

[0192] The total dead load design value is: G = 387.06 x 1.2 = 464.48 KN;

[0193] The dead load surface load design value is:

[0194] Live load calculation of main beam 25

[0195] The load generated by vibrating concrete is: 2 kN / m 2 ;

[0196] The human and construction load is: 2.5 kN / m 2

[0197] The total live load standard value is: 4.5 kN / m 2 ;

[0198] The total live load design value is: 4.5 x 1.4 = 6.3 kN / m 2 ;

[0199] Combination of forces on main beam 25

[0200] The unit weight of 25a# I-beam is 42.03 kg / m, so the self weight of 25a# I-beam is:

[0201] 5.1 x 42.03 x 10 / 1000 = 2.14 KN / m;

[0202] The uniform load design value: q = 1.4 x (65.05 + 6.3) + 2.14 = 102.03 N / mm;

[0203] Force calculation of main beam 25

[0204] The maximum spacing of main beam 25 is 460 mm, the span is: l = 5100 mm, the load is transmitted to 25a# I-beam through 8# channel steel, and the load is approximately uniformly distributed load:

[0205] The cross-sectional parameters of 4 25a I-beams are: W = 4 x 402 x 10 3 mm 3 ; I = 4 x 5020 x 10 4 mm 4 ;

[0206] Take three spans to calculate the maximum bending moment approximately as a continuous beam:

[0207] M = 0.1 ql 2 = 0.1 x 102.03 x 5100 2 = 265.38 x 106 N mm

[0208] Strength checking of main beam 25: Requirements are met.

[0209] Deflection checking of main beam 25:

[0210] Requirements are met.

[0211] The calculation method of side formwork 3 is as follows:

[0212] The side formwork 3 is made of newly purchased 12# channel steel 31. After being made, holes are opened on the 12# channel steel 31, 50×30mm wooden strips are nailed, and 18mm clamps are nailed on the wooden strips. Since the size of the side formwork is large, the side formwork 3 of the beam with a size of 4380×2200mm is the most unfavorable, so the side formwork with this size is taken as an example for checking.

[0213] The maximum lateral pressure of the newly poured concrete on the side formwork:

[0214] When using internal vibrators, the maximum lateral pressure of the newly poured concrete on the formwork can be calculated according to the following two formulas, and the smaller value of the two formulas is taken:

[0215]

[0216] F=γ c H=25×1.65=41.25KN / m 2 ;

[0217] In the formula: F - the maximum lateral pressure of the newly poured concrete on the formwork (KN / m 2 );

[0218] γ c - the gravity density of concrete (take 25 KN / m 3 );

[0219] t0 - the initial setting time of the newly poured concrete, use the formula where T is the temperature of the concrete ( 0 );

[0220] V - the pouring speed of the concrete;

[0221] H - the total height from the calculation position of the concrete lateral pressure to the top surface of the newly poured concrete (m);

[0222] β1 - the correction coefficient of the admixture, take 1.0 when there is no admixture, and take 1.2 when there is an admixture with a retarding effect;

[0223] β2 - the correction coefficient of the concrete slump, take 0.85 when the slump is less than 30mm; take 0.9 when the slump is 50-90mm

[0224] 1.0; 110~150mm, take 1.15;

[0225] Therefore, F = 41.25KN / m 2 ;

[0226] (1) The horizontal load generated when pouring concrete:

[0227] The horizontal load generated when pouring concrete is taken as the maximum value of 6kN / m 2 ;

[0228] (2) The standard value of the side pressure of the formwork:

[0229] q' = 41.25 + 6 = 47.25KN / m 2 ;

[0230] (3) The design value of the side pressure of the formwork:

[0231] q = 1.2 x 41.25 + 1.4 x 6 = 57.9KN / m 2 ;

[0232] Force calculation of each part of the side formwork 3

[0233] Calculation of the clamping plate 23

[0234] As can be seen from the figure, the clamping plate is a one-way plate, and when calculating, it can be approximately considered that the maximum span of the clamping plate is 320mm, and the thickness of the plate is 1.8cm; Select 1cm wooden board as the calculation unit, and the stress calculation is as follows:

[0235] q1 = 57.9 x 0.01 = 0.579N / mm;

[0236] Bending strength check:

[0237] The section parameters of the clamping plate 23 are:

[0238] Strength check: Satisfy the requirements;

[0239] Deflection check:

[0240]

[0241] 12# channel steel 31 check

[0242] The effective calculation length of the 12# channel steel 31 is: l = 1650mm; The width of the side pressure is 320mm;

[0243] q2 = 57.9 x 0.32 = 18.53N / mm;

[0244]

[0245] 12# channel steel 31 section parameters: W = 62.1 cm 3 ; I = 391 cm 4 ;

[0246] Strength calculation: Requirements are met.

[0247] Deflection calculation:

[0248] Requirements are met.

[0249] Corbel 4 bearing capacity checking:

[0250] All loads on the bottom die are finally concentrated on the corbel 4. According to the above checking, since the longitudinal beam corbel not only bears the construction load of the longitudinal beam itself but also bears the vertical downward pressure generated during the pouring process of the cross beam, the maximum concentrated force on the corbel is the support reaction force generated by the longitudinal beam support steel, which has been calculated in the above checking. The size of this force is P = 246.06 KN,

[0251] Corbel 4 is welded with Q355B steel with a thickness of 18 mm (see straight pile corbel structure diagram for details). In the most unfavorable case of horizontal steel plate checking, all forces are concentrated on the horizontal steel plate. The horizontal steel plate bears a force P = 246.06 KN. Therefore,

[0252] The bending moment of the corbel 4 is M = 246.06 x 0.5 = 123.03 kN.m,

[0253] Web section properties: W = b x h2 / 6 = 2 x 18 x 5002 / 6 = 1.5 x 106 mm 3

[0254] Web section area: A = b x h = 2 x 18 x 500 = 1.8 x 104 mm 3

[0255] The bending stress of the corbel 4 is σ = M / W = 123.03 x 106 / 1.5 x 106 = 82.02 <295 N / mm 2

[0256] The shear stress of the corbel 4 is τ = P / A = 246.06 x 103 / 1.8 x 104 = 13.67 <170 N / mm 2

[0257] Therefore, the corbel 4 meets the requirements.

[0258] Weld calculation

[0259] The size of the weld leg is: h w ≥ 8 mm

[0260] The weld length is: l w = 50 cm

[0261] The weld can withstand the maximum shear force Nmax

[0262] The weld shear strength design value f t w = 200 N / mm 2

[0263] Nmax = 0.7f t w · l w · h w = 0.7 x 200 x 8 x 500 = 560 KN

[0264] Considering a safety factor of 1.5, the carrying capacity of each bracket is 246.06 x 1.5 = 369.09 KN

[0265] The carrying capacity of bracket 4 is 560 kN, so bracket 4 can meet the requirements as a construction platform support.

[0266] In summary, the present application provides a design method for cast-in-place beam formwork. The load on the bottom formwork can be divided into dead load and live load for separate checking by the design method of the present application. The total load on the bottom formwork during construction can be obtained, and the stress and deflection parameters of the bottom formwork can be further calculated. The calculated stress and deflection parameters are compared with the parameter values specified in the construction specification standard. If the values are less than the standard values, the strength requirement is met. If the values are greater than the standard values, the size of the steel structure in the bottom formwork needs to be further adjusted until the checking meets the requirements again. The design method can obtain the bottom formwork design parameters that just meet the strength requirements, which can ensure that the bottom formwork meets the strength requirements while using the least amount of steel structure, reducing the construction workload and improving the construction efficiency. In addition, the self-weight of the formwork structure is also reduced, which facilitates demolding after pouring.

[0267] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of designing a cast-in-place beam form, characterized by, The cast-in-place beam formwork comprises a bottom formwork (2) and a side formwork (3), the bottom formwork (2) is horizontally erected between a plurality of steel pipe piles (1), and the side formwork (3) is vertically installed on the bottom formwork (2); The design method comprises a load calculation step of the bottom formwork (2), which comprises: S1: respectively calculating dead load of the bottom formwork (2) and live load of the bottom formwork (2), the dead load of the bottom formwork (2) comprising gravity of the bottom formwork (2), gravity of the side formwork (3) and gravity of reinforced concrete, and the live load of the bottom formwork (2) comprising load generated by concrete vibration, load generated by personnel and construction; S2: calculating total load of the bottom formwork (2) according to the dead load of the bottom formwork (2) and the live load of the bottom formwork (2); S3: calculating stress and deflection of the bottom formwork (2) according to the size of the bottom formwork (2); S4: judging whether the strength of the bottom formwork (2) meets the requirements according to the stress and deflection of the bottom formwork (2); The bottom formwork (2) comprises a transverse beam bottom form (21) and a longitudinal beam bottom form (22) perpendicular to each other, the transverse beam bottom form (21) is erected on the longitudinal beam bottom form (22), and the transverse beam bottom form (21) and the longitudinal beam bottom form (22) each comprise a clamping plate (23), a plurality of secondary beams and a plurality of main beams (25); The design method comprises a load calculation step of the transverse beam bottom form (21) and the longitudinal beam bottom form (22), which comprises: A1: calculating dead load of the clamping plate (23), the secondary beam (24) or the main beam (25), and calculating live load of the clamping plate (23), the secondary beam (24) or the main beam (25); A2: calculating total load of the clamping plate (23), the secondary beam (24) or the main beam (25) according to the dead load and the live load of the clamping plate (23), the secondary beam (24) or the main beam (25); A3: calculating stress and deflection of the clamping plate (23), the secondary beam (24) or the main beam (25) according to the size of the clamping plate (23), the secondary beam (24) or the main beam (25); A4: judging whether the strength of the clamping plate (23), the secondary beam (24) or the main beam (25) meets the requirements according to the stress and deflection of the clamping plate (23), the secondary beam (24) or the main beam (25); A plurality of the main beams (25) are connected by welding or bolt fixing, a plurality of the secondary beams (24) are fixed on the main beams (25) by welding or bolt fixing, a plurality of the main beams (25) are located in a first plane, a plurality of the secondary beams (24) are located in a second plane, and the first plane and the second plane are parallel and arranged at intervals; The design method further comprises a load calculation step of the side formwork (3), which comprises: B1: calculating maximum lateral pressure F generated by concrete vibration on the side formwork (3) and horizontal load F' generated by pouring concrete; B2: calculating total load of the side formwork (3) according to the maximum lateral pressure F generated by concrete vibration on the side formwork (3) and the horizontal load F' generated by pouring concrete.

2. The method of designing a cast-in-place beam form according to claim 1, wherein The maximum side pressure F is calculated by the following formula: （1） And （2） The maximum side pressure F is the smaller value between formula (1) and formula (2).

3. The method of designing a cast-in-place beam form according to claim 1, wherein The horizontal load F' generated by the pouring of concrete takes a maximum value of 6 kN / m 2 .

4. The method of designing a cast-in-place beam form according to claim 1, wherein The total load of the side formwork (3) is calculated by calculating the standard value q' of side pressure and the design value q of side pressure respectively, q'=F+F'; q=F×dead load partial coefficient+F'×live load partial coefficient; The dead load partial coefficient is 1.2 and the live load partial coefficient is 1.

4.

5. The method of designing a cast-in-place beam form according to claim 1, wherein, The side formwork (3) comprises a clamping plate (23) and several channel steels, and the load calculation step of the side formwork (3) further comprises: C1: calculating the stress and deflection of the clamping plate (23) and the stress and deflection of the channel steel respectively; C2: judging whether the stress and deflection of the clamping plate (23) and the channel steel meet the requirements.

6. The method of designing a cast-in-place beam form according to claim 5, wherein, The formula for calculating the stress σ of the clamping plate (23) and the channel steel is: σ=M / W In the formula, M is the bending strength and W is the cross-section parameter; The formula for calculating the deflection ω of the clamping plate (23) and the channel steel is: In the formula, M is the bending strength, l is the maximum span size of the clamping plate (23) or the channel steel, E is the elastic modulus of the clamping plate (23) or the channel steel, and I is the cross-sectional moment of inertia of the clamping plate (23) or the channel steel.

7. The method of designing a cast-in-place beam form according to any one of claims 1 to 6, wherein The steel pipe pile (1) is provided with several corbels (4), and the bottom formwork (2) is erected on the corbels (4); The design method further comprises a load calculation step of the corbel (4), comprising: D1: calculating the bending stress and shear stress parameters of the corbel (4) respectively; D2: judging whether the strength of the corbel (4) meets the requirements according to the bending stress and shear stress parameters of the corbel (4).

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