A design method for connecting a steel pipe pile and a platform of an overhead transmission line over water

Abstract

The application discloses a kind of water overhead transmission line steel pipe pile-platform connection design method, define the range of D area;Determine the action of main force, generally including axial force, bending moment, shear force, torque etc.;Determine the plastic strength of steel pipe pile section, steel pipe concrete;The load determined is transferred to D area tension-compression strut model;Check the bearing capacity of tension rod and compression rod in model;Check the bearing capacity of node in model;Based on tension rod-compression strut model stress, determine the detailed reinforcement design of different parts.In the steel pipe pile and pile cap connection of water overhead transmission line is a very complex mechanical model, using tension-compression strut model can simplify the complex model into simple truss model, the stress of different tension-compression strut elements is calculated by stress balance method, and the material strength and the amount of reinforcement required can be verified by calculation, which has important guiding significance for pile-cap connection calculation of water overhead line.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power transmission lines, in particular to a water overhead power transmission line steel pipe pile-platform connection design method. BACKGROUND

[0002] The water overhead power transmission line platform often involves a rigid platform and a steel pipe pile foundation, and the connection between the steel pipe pile foundation and the platform is the key to the design. In the traditional bearing capacity limit state design, the connection design of the node is determined based on the bending moment, shear force and axial force of the node. This design method cannot clearly express the force transmission path in the structure system, and cannot calculate the key local stress. When calculating the normal use limit state design, the stress size at different positions cannot be accurately expressed.

[0003] In order to solve the above problems, the present application defines the internal truss structure, determines the tension rod and compression rod model under different load combinations, and determines the load transmission path on the steel pipe pile foundation and the platform, so as to more economically and reasonably carry out the node design. SUMMARY

[0004] The purpose of the present application is to provide a water overhead power transmission line steel pipe pile-platform connection design method to solve the problems raised in the background art.

[0005] To achieve the above purpose, the present application provides the following technical scheme:

[0006] A water overhead power transmission line steel pipe pile-platform connection design method, comprising the following steps:

[0007] Step 1: establishing a tension-compression rod model, the tension-compression rod model comprising a concrete platform and a steel pipe pile for supporting the concrete platform;

[0008] The point on the surface of the steel pipe pile with a distance h1 from the lower surface of the concrete platform is set as the bottom rod pressure load action point, and the point on the surface of the steel pipe pile with a distance h2 from the upper surface of the concrete platform is set as the top rod pressure load action point, and the bottom rod pressure load action point and the top rod pressure load action point are diagonally arranged;

[0009] Step 2: presetting the section of the steel pipe pile, the wall thickness t plate , the number of shear keys nos, and the material yield strength;

[0010] Step 3: setting the bottom rod pressure and the top rod pressure of the load action points h1 and h2 of the tension-compression rod model;

[0011] Step 4: inputting the data determined in steps 2 and 3 into the tension-compression rod model;

[0012] Step 5: checking the wall thickness t of the steel pipe pileplate , the number of shear keys nos, the maximum shear strength of concrete V RDi Whether the demand is met.

[0013] Preferably, h1=h2=the diameter of the steel pipe pile.

[0014] Preferably, the concrete platform comprises solid tie beams and hollow tie beams; the steel pipe pile with a solid tie beam and a length of 1 times the diameter of the steel pipe pile below the bottom wall of the solid tie beam is defined as a D area.

[0015] Preferably, the bottom rod pressure and the top rod pressure are converted into the bottom rod horizontal force F of the h1, h2 load action point according to mechanical balance. h1 , the bottom rod vertical force F v1 , the top rod horizontal force F h2 , the top rod vertical force F v2 and the pressure rod force F strut .

[0016] Preferably, the half perimeter yield bearing capacity F of the steel pipe pile is calculated by the following formula: plate :

[0017] F h1 = F h2 = M / z

[0018]

[0019]

[0020] In the formula, M is the bending moment value of the connecting node (M is the actual node load-preset value, calculated F h1 , F h2 is used to verify the actual load and bearing capacity), z is the distance of the F h1 and F h2 load action point, and d is the diameter of the steel pipe pile.

[0021] Preferably, the wall thickness t of the steel pipe pile is calculated by the following formula: plate , and compared with the preset value to verify whether the wall thickness t plate design is reasonable:

[0022] F Plate = Q plate *C 1 / 2

[0023] Q plate = fy*t plate

[0024] R i = R out -t plater / 2

[0025] C 1 / 2 = πR i

[0026] wherein fy is the yield strength of the steel pipe pile material, R out is the radius of the steel pipe pile, R i is the radius of the center point of the wall thickness of the steel pipe pile.

[0027] Preferably, the pressure transmitted by the shear key in the height range of h1 or h2 is checked to not exceed the shear strength of the internal concrete, and the maximum shear strength of the concrete V RDi The formula is as follows:

[0028] V RDi ≤ 0.5vf cd

[0029]

[0030] V RDi *h1*C 1 / 2 ≥ F plate

[0031] wherein f cd is the design value of the compressive strength of the concrete, f ck is the characteristic value of the compressive strength of the concrete.

[0032] Preferably, the shear key can transmit the yield load capacity of the half circumference of the steel pipe pile, and the number of shear keys nos is calculated from the following formula, so as to verify whether the design of the number of shear keys is reasonable:

[0033] h1 = h2 = d

[0034] nos = F plate / R key

[0035] R key = min(R1, R2)

[0036] wherein the range of d is also the range in which the shear key is set, R1 is the yield strength of the shear key, and R2 is the allowable compressive load capacity of the concrete around the shear key.

[0037] Preferably, the size of the reinforcement corresponding to the area is calculated according to the bottom bar pressure and the top bar pressure of the tension-compression bar model:

[0038] A s1 = A s2 = F h1 (F h2 ) / f sd

[0039] wherein f sdDesign value of tensile strength of steel bar;

[0040] Through the calculation section analysis of the compression bar, the section shape is an ellipse, one half axis L1 of the ellipse is the radius d / 2 of the steel pipe pile, and the calculation formula of the other half axis L2 of the ellipse is as follows:

[0041]

[0042] Therefore, the simulated compression bar stress σ strut (Compared with the calculated concrete compressive strength of this section) formula is as follows:

[0043] σ strut = F strut / A strut

[0044] A strut = πL1L2

[0045] In the formula, A strut is the calculation section of the compression bar.

[0046] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the method for designing the connection between the steel pipe pile and the platform of the overhead transmission line on water as described.

[0047] Compared with the prior art, the beneficial effects of the present application are:

[0048] The connection between the steel pipe pile and the platform in the overhead transmission line on water is a very complex mechanical model, the complex model can be simplified into a simple truss model by using the tension-compression bar model, the stress of different tension-compression bar elements is calculated by the method of force balance, and the material strength and the required reinforcement amount can be verified through the calculation, which has important guiding significance for the pile-platform connection calculation of the overhead transmission line on water. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed for the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0050] Figure 1 The figure is a schematic diagram of the pile-platform D area connection design structure of the present application;

[0051] Figure 2 The figure is a schematic diagram of the tension-compression bar model structure of the present application;

[0052] Figure 3 A sectional view of the tension-compression bar model of the present application;

[0053] Figure 4 A schematic diagram of the D region structure of the present application;

[0054] Figure 5 A stress distribution diagram of the D region tension-compression bar model under the action of counterclockwise bending moment of the present application;

[0055] Figure 6 A stress distribution diagram of the D region tension-compression bar model under the action of clockwise bending moment of the present application;

[0056] Figure 7 A mechanical equilibrium diagram of the D region tension-compression bar model under the action of counterclockwise bending moment of the present application;

[0057] Figure 8 A mechanical equilibrium diagram of the D region tension-compression bar model under the action of clockwise bending moment of the present application;

[0058] Figure 9 A schematic diagram of the steel pipe pile of the present application;

[0059] Figure 10 A schematic diagram of the shear key of the present application;

[0060] Figure 11 A stress analysis diagram of the steel pipe pile of the present application;

[0061] Figure 12 A mechanical equilibrium schematic diagram of the bottom bar pressure and the top bar pressure of the present application;

[0062] Figure 13 A schematic diagram of the stress section of the compression bar force of the present application;

[0063] Figure 14 A schematic diagram of the node checking structure of the tension-compression bar model of the present application;

[0064] Figure 15 A schematic diagram of the F h1 , F v1 and F strut force acting width of the present application.

[0065] 1, steel pipe pile; 2, concrete platform; 3, iron tower; 4, D region; 5, solid tie beam; 6, flange plate; 7, hollow tie beam; 8, shear key; 10, reinforced concrete. DETAILED DESCRIPTION

[0066] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0067] Embodiment:

[0068] (1) A tension-compression strut model (diagonal compression strut model) is proposed, the reinforced concrete 10 inside the steel pipe pile 1 is regarded as a compression strut model, and the reinforcement area at the top and bottom is regarded as a tension strut area, and then the reinforcement configuration at the connection is calculated.

[0069] (2) A D area tension-compression strut model design method flow is proposed, the definition purpose of the D area 4 is to analyze the stress condition in the area, and then to solve the stress state of the components connected with the area, so as to be applied to the pile-platform connection design field of the overhead transmission line on water.

[0070] As shown in Figure 2 and Figure 3 , the tension-compression strut model includes a steel pipe pile 1, a concrete platform 2 and a tower 3, the overhead transmission line tower load is transmitted to the concrete platform 2 and the steel pipe pile 1 through the tower 3. The concrete platform 2 is composed of a solid beam 5, a hollow beam 7 and a flange plate 6. As shown in Figure 1 , the components of the D area 4 involve the solid beam 5, the hollow beam 7, the steel pipe pile 1 and the reinforced concrete 10 in the steel pipe pile 1, wherein the reinforced concrete 10 in the steel pipe pile 1 forms a composite cross-section material with the steel pipe pile.

[0071] As shown in Figure 4 , the size of the D area 4 is: the overall height and contour of the concrete solid beam 5, the length of the steel pipe pile 1 below the solid beam 5 is 1 times the pile diameter of the steel pipe pile 1;

[0072] The size of the D area 4 is determined as follows:

[0073] The height of the D area 4 is the height H of the solid beam 5 plus the pile diameter d of the steel pipe pile 1, and the width of the D area 4 is the outer concrete thickness t of the steel pipe pile 1 plus the pile diameter d of the steel pipe pile 1 plus the height H of the solid beam 5. After defining the D area 4, the interface between the inside and the outside of the area is mainly the mutual connection of the reinforcement on the side surface of the model and the steel pipe pile 1 and the reinforced concrete 10 on the bottom surface of the model. The stress of the interface can be calculated by the stress of the model, and then the relevant material configuration is determined.

[0074] (1) Calculation of D area stress

[0075] The external loads on region D4 can be simplified to axial force, shear force, and bending moment. Within region D4, the effects of axial force and shear force are relatively small compared to the effects of bending moment. Figures 5-6 As shown, therefore, considering different directions and bending moments (clockwise and counterclockwise bending moments), it can be simplified to a lateral force F with different center distances. h1 and F h2 The forces acting on the load are calculated as follows: h1 is calculated from the bottom of the solid tie beam 5 in region D 4 upwards, and h2 is calculated from the top of the solid tie beam 5 in region D 4 downwards. Both are taken as one times the diameter of the steel pipe pile 1, i.e., h1 = h2 = d.

[0076] After simplifying the stress distribution, the concrete of the inclined steel pipe pile 1 is defined as an inclined compression member, such as... Figures 7-8 As shown, the force F acting on the oblique compression bar strut Through the force of the oblique compression bar, the internal force balance of region D 4 is achieved.

[0077] (2) Tension-compression bar bearing capacity verification

[0078] 1) Verification of steel pipe pile wall thickness

[0079] like Figure 9 As shown, the wall thickness of the steel pipe pile is known to be t. plate The yield strength of the steel pipe pile material is fy, and the yield bearing capacity of steel pipe pile 1 per linear meter (calculated based on a 1m perimeter) is Q. plate =fy* tplate The perimeter C of half of the steel pipe pile 1 / 2 =πR i , where R i It is the radius of the center point of the steel pipe pile wall thickness, calculated by the formula R. i =R out -t plater / 2.

[0080] Therefore, the semi-circumference yield bearing capacity F of steel pipe pile 1 Plate =Q plate *C 1 / 2 The axial force borne by the steel pipe pile 1 is transmitted to the reinforced concrete 10 inside the steel pipe pile 1 through the shear key 8. By comparing the semi-circumference yield bearing capacity of the steel pipe pile 1 and F... v1 (F V1 Less than F plate To verify whether the design of steel pipe pile 1 in the 4-node design of the relevant D area is reasonable.

[0081] (2) Verification of the number of shear keys

[0082] like Figure 10 As shown, the bearing capacity of shear key 8 is calculated as follows:

[0083] R key = min(R1, R2)

[0084] R1 is the yield strength of shear key 8, and R2 is the allowable compressive bearing capacity of the concrete around the shear key 8. The allowable compressive bearing capacity of the concrete can be performed according to the Code for Design of Concrete Structures GB50010-2010 or BS5400-4: Code of Practice for Design of Concrete Bridges.

[0085] It is assumed that the shear key 8 can transfer the yield bearing capacity F of half the circumference of the steel pipe pile 1 plate , and the number of shear keys 8 required in the range of h1 and h2 is calculated as follows.

[0086] h1 = h2 = d

[0087] nos = F plate / R key

[0088] At the same time, it is necessary to check that the pressure transferred by the shear key 8 in the range of h1 or h2 height does not exceed the shear strength of the internal concrete. According to the relevant provisions of Eurocode 2 (EN 1992-1-1:2005) §6.2.5, the maximum shear strength of concrete V RDi The formula is as follows:

[0089] V RDi ≤ 0.5vf cd

[0090]

[0091] V RDi *h1*C 1 / 2 ≥ F plate

[0092] In the formula: f cd is the design value of the compressive strength of concrete, and f ck is the characteristic value of the compressive strength of concrete (similar to the standard value of domestic compressive strength of concrete).

[0093] (3) Checking of the joint

[0094] As shown in Figures 11-13 , considering the ultimate plastic load of the steel pipe pile 1, F h1 , and the bending moment generated by F h2 and the external load is the same as the bending moment of the joint, so the calculation formula of Fh1 is as follows

[0095] F h1 = F h2= M / z

[0096] where M is the bending moment value of the connection node, and z is the distance from the load action point. h1 and F h2 the distance from the load action point.

[0097] Through geometric calculation, the angle of the diagonal strut in the steel pipe pile is The calculation formula is as follows:

[0098]

[0099] According to the mechanical equilibrium, the maximum diagonal strut force F strut is calculated when the steel pipe yields.

[0100]

[0101] Through the above calculation of the stress, the stress characteristics of each element of the tension-compression strut model are verified. In particular, the bearing capacity of the following three regions needs to be checked: (1) the concentrated action area of the top solid beam and the steel pipe pile F h2 ; (2) the concentrated force area of the bottom ring-shaped concrete and the steel pipe pile F h1 ; (3) the diagonal strut force F strut (F h1 , F h2 The value calculated by M is smaller than the value calculated by the two-force balance of F plate , and the stress calculated by F strut is smaller than the compressive strength of the concrete).

[0102] According to the force of the solid beam 5 at the top and bottom of the D area tension-compression strut model, the size of the corresponding area of reinforcement is calculated.

[0103] A s1 = A s2 = F h1 (F h2 ) / f sd

[0104] In the formula, f sd represents the design value of the tensile strength of the steel bar.

[0105] Through the calculation of the cross section of the strut, the cross section shape is an ellipse. The long half axis L1 of the ellipse is the radius d / 2 of the steel pipe pile 1, and the calculation formula of the short half axis L2 of the ellipse is as follows:

[0106]

[0107] Therefore, the simulated strut stress σ strut in the D area tension-compression strut model is as follows:

[0108] σstrut = F strut / A strut

[0109] A strut = πL1L2

[0110] wherein: A strut is the calculated section of the compression bar.

[0111] 3) Tension-compression bar model node checking

[0112] As shown in the figure, the tension bar or compression bar element in the D area tension-compression bar model is connected and transmitted through the node, and sufficient strength needs to be ensured at the node. Figures 14-15 From node N1, it can be seen that there are three directions of force, which are the bottom horizontal tension bar F h1 (F h2 ), the diagonal compression bar F strut and the vertical compression bar F v1 (F v2 ). The action width of the three forces is detailed in

[0113] , by checking the relationship between the stress per unit area and the material allowable stress, checking the bearing capacity at the node (the checking includes the local compressive strength of the concrete under the action of F v1 , F strut and the material strength of the steel pipe pile 1 under the action of F v1 ). The material allowable stress here includes the yield strength of the steel pipe, the designed compressive strength of the concrete and the designed strength of the steel pipe pile. Figure 15 (4) D area tension-compression bar model design checking output

[0114] The design checking output mainly includes:

[0115] 1) Calculate the stress of the steel pipe through F v1 , and then check whether the wall thickness of the steel pipe pile 1 can meet the requirements;

[0116] 2) Calculate the number of shear keys 8 through the limit bearing capacity of the half perimeter of the steel pipe, and check the local compressive and shear bearing capacity of the concrete on the contact surface of the shear keys 8 in the steel pipe pile 1;

[0117] 3) Check the local compressive bearing capacity of the concrete inside the steel pipe pile 1 under the corresponding action area of F strut and the like through node checking;

[0118] 4) Calculate the reinforcement of the solid beam 5 or hollow beam 7 outside the D area through F h1 and F h2 calculated by the D area 4.

[0119] ​

[0120] (5) D region tension-compression bar model design process

[0121] The following is the process step of D region tension-compression bar model design

[0122] 1) Define the scope of D region;

[0123] 2) Determine the main force action, generally including axial force, bending moment, shear force, torque, etc;

[0124] 3) Determine the steel pipe pile section and the plastic strength of the steel pipe concrete;

[0125] 4) Transfer the load determined in steps 2 and 3 to the D region tension-compression bar model;

[0126] 5) Check the bearing capacity of the tension bar and the compression bar in the model;

[0127] 6) Check the bearing capacity of the node in the model;

[0128] 7) Based on the stress of the tension-compression bar model, determine the detailed reinforcement design of different parts.

[0129] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0130] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and do not limit the application to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of the present specification. The present specification selects and describes these embodiments in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited only by the claims and their entire scope and equivalents.

Claims

1. A method for designing a steel pipe pile-platform connection of an overhead water transmission line, characterized in that: The method comprises the following steps: Step 1: establishing a tension-compression bar model, the tension-compression bar model comprising a concrete platform (2) and a steel pipe pile (1) for supporting the concrete platform (2); Points on the surface of the steel pipe pile (1) at a distance h1 from the lower surface of the concrete platform (2) are set as bottom bar pressure load action points, and points on the surface of the steel pipe pile (1) at a distance h2 from the upper surface of the concrete platform (2) are set as top bar pressure load action points, and the bottom bar pressure load action points and the top bar pressure load action points are arranged diagonally; Step 2: preset the section of the steel pipe pile (1), the wall thickness t plate , the number of shear keys (8) nos, the material yield strength; Step 3: setting the bottom bar pressure and the top bar pressure of the load action points h1 and h2 of the tension-compression bar model; Step 4: inputting the data determined in steps 2 and 3 into the tension-compression bar model; Step 5: Check the wall thickness t of the steel pipe pile (1) plate the number of shear keys (8) nos, the maximum shear strength of the concrete whether the demand is met; The bottom rod pressure and the top rod pressure are converted into the bottom rod horizontal force F of the h1 and h2 load action points according to mechanical balance h1 , the bottom rod vertical force F v1 , the top rod horizontal force F h2 , the top rod vertical force F v2 and the counter-pressure rod force F strut ; The half-circumferential yield load F of the steel pipe pile (1) is calculated by the following formula plate : In the formula, M is the bending moment value of the connecting node, z is F h1 and F h2 the distance of the load action point, d is the pile diameter of the steel pipe pile (1); The shear key (8) can transmit the yield bearing capacity of the half circumferential length of the steel pipe pile, and the number nos of the shear key (8) is calculated from the following formula, so as to verify whether the number design of the shear key (8) is reasonable: In the formula, R1 is the yield strength of the shear key (8), and R2 is the allowable compressive bearing capacity of the concrete around the shear key (8).

2. The method for designing the connection between the steel pipe pile and the platform of the overhead transmission line on water according to claim 1, characterized in that: The concrete platform (2) comprises a solid tie beam (5) and a hollow tie beam (7); the solid tie beam (5) and the steel pipe pile (1) with a length of 1 times the pile diameter of the steel pipe pile (1) below the bottom wall of the solid tie beam (5) are defined as a D area (4).

3. The method for designing the connection between the steel pipe pile and the platform of the overhead transmission line on water according to claim 1, characterized in that: The wall thickness t of the steel pipe pile (1) is calculated from the following formula plate compared with the preset value to verify the wall thickness t plate Is the design reasonable: Q plate =fy*t plate In the formula, fy is the material yield strength of the steel pipe pile (1), R out is the radius of the steel pipe pile (1), R i is the radius of the center point of the wall thickness of the steel pipe pile (1).

4. The method for designing the connection between the steel pipe pile and the platform of the overhead transmission line on water according to claim 3, characterized in that: It is necessary to check that the pressure transmitted by the shear key (8) in the range of heights h1 or h2 does not exceed the shear strength of the internal concrete, the maximum shear strength of the concrete The formula is as follows: In the formulae: is the design value of the compressive strength of concrete, is the characteristic value of the compressive strength of concrete.

5. The method for designing the connection between the steel pipe pile and the platform of the overhead transmission line on water according to claim 1, characterized in that: According to the bottom bar pressure and the top bar pressure of the tension-compression bar model, the reinforcement size of the corresponding area is calculated: In the formula, design value of tensile strength of the reinforcing bar; Through the calculation of the cross section of the compression bar, the cross section shape is an ellipse, one half axis L1 of the ellipse is the radius d / 2 of the steel pipe pile (1), and the calculation formula of the other half axis L2 of the ellipse is as follows: Thus the simulated compressive bar stress in the tension-compression bar model The formula is as follows: In the formulae: A is the calculated cross section of the compression strut.

6. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the method for designing the connection between a steel pipe pile and a platform of an overhead transmission line on water according to any one of claims 1-5 when executing the program.

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