CN111209707B - Friction type bolt connection node under combined action of compression shear, method and system - Google Patents
Friction type bolt connection node under combined action of compression shear, method and system Download PDFInfo
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Abstract
The invention discloses a friction type bolt connection node bearing the combined action of compression and shear, a method and a system thereof, comprising the following steps: establishing a finite element model of a connecting plate, a bearing plate and a connecting bolt which are contained in the connecting node; defining parameters of contact, load, friction coefficient and boundary condition of the finite element model to obtain initial sliding load of the connecting node; regression analysis is carried out to obtain a relation formula of initial sliding load of the connecting node and connecting node parameters; and designing the anti-sliding bearing capacity of the friction type bolt connection node under the combined action of pressure and shear through a regression relation formula.
Description
Technical Field
The disclosure belongs to the technical field of steel structures, and particularly relates to a friction type bolt connection node bearing a compression-shear combined effect, a method and a system.
Background
The steel member nodes connected by high-strength bolts are divided into friction type bolting nodes and pressure-bearing type bolting nodes. The former is suitable for structural engineering connection of dynamic load and fatigue load, and is widely applied to construction and bridge engineering. It is increasingly common for structural engineering connection nodes to simultaneously withstand pressure and shear forces, such as connecting T-shaped nodes in steel diagonal bracing and cable-stayed transformation variable-section concrete box girder bridge reinforcement systems. At present, the design of the anti-slip bearing capacity of the friction type high-strength bolt connection T-shaped node under the action of the tension-shear combination is written into the standard, however, the anti-slip bearing capacity of the node under the action of the compression-shear combination has obvious research deficiency, and the design standard and the powerful research result are not only lacked. The designer only confirms the bolt quantity according to the design value of the friction type connection bearing capacity of each high-strength bolt of the shear connection node in the steel structure specification, and does not consider the friction force generated by the load in the normal direction of the contact surface of the connecting plate, thereby greatly increasing the use amount of the high-strength bolts. According to the design, the cost of engineering materials is increased, unnecessary resource waste is caused, and meanwhile, the high construction cost is also increased.
Disclosure of Invention
The present disclosure aims to overcome the above-mentioned shortcomings in the prior art, and provide a friction type bolting node, method and system for bearing the combined action of compression and shear; the design method adopts a finite element method to simulate the anti-slip bearing capacity of the connecting node under different influence parameters, and finally regression analysis is carried out on the relational expressions of the different parameters and the anti-slip bearing capacity.
The first object of the present disclosure is to provide a design method of a friction type bolting node bearing the combined action of compression and shear, and in order to achieve the above object, the present disclosure adopts the following technical scheme:
a design method of a friction type bolt connection node bearing the combined action of compression and shear comprises the following steps:
establishing a finite element model of a connecting plate, a bearing plate and a connecting bolt which are contained in the connecting node;
defining parameters of contact, load, friction coefficient and boundary condition of the finite element model to obtain initial sliding load of the connecting node;
regression analysis is carried out to obtain a relation formula of initial sliding load of the connecting node and connecting node parameters;
and designing the anti-sliding bearing capacity of the friction type bolt connection node under the combined action of pressure and shear through a regression relation formula.
As a further technical scheme, the connecting plates and the bearing plates of the connecting nodes are two, the two connecting plates are in opposite contact, each connecting plate is connected with one bearing plate, the two connecting plates are connected through connecting bolts, after the finite element model of the connecting plates, the bearing plates and the connecting bolts is built, equiaxial constraint is built between the bolt holes of the connecting plates and the connecting bolts, and pretightening force is applied to the connecting bolts.
As a further technical solution, the initial sliding load of the connection node is obtained by:
the method comprises the steps of defining contact, load, friction coefficient and boundary condition parameters of a finite element model by the finite element model of a connecting node, establishing full constraint of degree of freedom on the lower surface of a bearing plate positioned at the lower part, applying vertical downward displacement constraint on the upper surface of the bearing plate positioned at the upper part, analyzing to obtain a stress cloud picture, and further obtaining the relative sliding quantity between two connecting plates and the pressure born by the bearing plate positioned at the upper part, wherein the pressure is the initial sliding load of the connecting node.
As a further technical scheme, the parameters of the connecting node comprise a compression-shear ratio, a friction coefficient, a bolt pretightening force, a connecting bolt diameter and a connecting plate thickness.
As a further technical scheme, the initial sliding load, the compression-shear ratio and the friction coefficient of the connecting node are in nonlinear relation, and a quadratic curve a+bx+cx is adopted 2 Fitting; the initial sliding load of the connecting node and the bolt pretightening force are in linear relation, and linear equation a+bx fitting is adopted; the thickness of the connecting plate has no influence on the initial sliding load.
As a further technical scheme, substituting the numerical value of the connection node parameter into a relation formula of the initial sliding load and the connection node parameter to obtain the initial sliding load of the connection node, namely the anti-sliding bearing capacity of the connection node.
As a further technical scheme, judging whether the anti-slip bearing capacity of the connection node meets the bearing requirement, and if not, modifying the connection node parameters until the connection node parameters meet the bearing requirement.
A second object of the present disclosure is to provide a design system of a friction type bolting node subjected to a compression shear combined action, comprising:
the model building module is used for building a finite element model of the connecting plate, the bearing plate and the connecting bolt which are contained in the connecting node;
the definition module is used for defining contact, load, friction coefficient and boundary condition parameters of the finite element model to obtain initial sliding load of the connecting node;
the analysis module is used for regression analysis of a relation formula of the initial sliding load of the connection node and the connection node parameter;
and the design module is used for designing the anti-sliding bearing capacity of the friction type bolt connection node under the combined action of the pressure shear through a regression relation formula.
The third object of the present disclosure is to provide a connection node designed according to the design method of the friction type bolting connection node for the bearing shear combined action as described above, which comprises an upper bearing plate, a lower bearing plate, an upper connecting plate, a lower connecting plate and a connecting bolt, wherein the bottom of the upper bearing plate is fixedly connected with the upper connecting plate, the upper connecting plate is obliquely arranged, the top of the lower bearing plate is fixedly connected with the lower connecting plate, the lower connecting plate is mutually parallel to the upper connecting plate, the upper connecting plate and the lower connecting plate are closely arranged, the upper bearing plate and the lower bearing plate are vertically arranged, a plurality of bolt holes are formed in the upper connecting plate and the lower connecting plate, the connecting bolt is penetrated in the bolt holes, and the connecting bolt fastens and connects the upper connecting plate and the lower connecting plate.
As a further technical scheme, the top of the upper bearing plate is a plane parallel to the horizontal, the bottom of the lower bearing plate is a plane parallel to the horizontal, an included angle is formed between the axis of the connecting bolt and the vertical surface, and the two connecting plate surfaces are respectively perpendicular to the two bearing plate surfaces.
The beneficial effects of the present disclosure are:
according to the design method, different compression-shear ratios of the T-shaped connecting node of the friction type high-strength bolt can be simulated by changing the size of the pressure bearing plate, and meanwhile, the method is convenient for factory processing, is convenient to install and detach, and has definite stress performance. In addition, a regression analysis method is adopted to fit design calculation formulas of T-shaped connection nodes of the friction type high-strength bolts and different parameters, and a reference is provided for steel structure engineering design.
The design method of the present disclosure can greatly reduce the number of bolts relative to existing connection node design methods. The design specifications at home and abroad are not specific to the design method of the connecting joint under the combined action of pressure and shear, and the quantity of bolts is determined by adopting a friction type high-strength bolt connecting node shearing bearing capacity calculation method at present. Therefore, the shearing load capacity provided to the connection node by the pressure effect is not considered, thereby increasing the actual use amount of the bolts.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute an undue limitation to the application.
FIG. 1 is a schematic diagram of the frontal dimensions of a T-shaped connection node for a friction-type high strength bolt according to embodiment 1 of the present disclosure;
FIG. 2 is a schematic side view of a T-shaped connection node of a friction type high strength bolt according to example 1 of the present disclosure;
FIG. 3 is a schematic illustration of the dimensions of a friction type high strength bolt T-shaped connection node connection plate in example 1 of the present disclosure
FIG. 4 is a schematic illustration of a friction type high strength bolt T-joint connection node contact, load application and boundary conditions as defined in model example 2 of the present disclosure;
fig. 5 (a) is a finite element analysis model diagram of a friction type high strength bolt T-shaped connection node with a diameter of 20mm, a compression shear ratio λ= 0.7002 (θ=35°) established in example 2 of the present disclosure;
fig. 5 (b) is a sliding diagram of a friction type high strength bolt T-shaped connection node finite element analysis model with a diameter of 20mm, a compression shear ratio λ= 0.7002 (θ=35°) established in example 2 of the present disclosure;
fig. 6 (a) is a diagram of a simulated finite element analysis model of a friction type high strength bolt T-joint with a diameter of 20mm, a compression shear ratio λ=1.0000 (θ=45°) in example 2 of the present disclosure;
fig. 6 (b) is a sliding diagram of a friction type high strength bolt T-shaped connection node finite element analysis model with a diameter of 20mm, a compression shear ratio λ=1.0000 (θ=45°) simulated in example 2 of the present disclosure;
fig. 7 (a) is a diagram of a simulated finite element analysis model of a friction type high strength bolt T-joint with a diameter of 20mm, a compression shear ratio λ= 1.4281 (θ=55°) in example 2 of the present disclosure;
fig. 7 (b) is a sliding diagram of a simulated friction type high strength bolt T-joint finite element analysis model with a diameter of 20mm, a compression shear ratio λ= 1.4281 (θ=55°) in example 2 of the present disclosure;
fig. 8 (a) is a diagram of a simulated finite element analysis model of a friction type high strength bolt T-joint with a diameter of 20mm, a compression shear ratio λ= 1.7321 (θ=60°) in example 2 of the present disclosure;
fig. 8 (b) is a sliding diagram of a simulated friction type high strength bolt T-joint finite element analysis model with a diameter of 20mm, a compression shear ratio λ= 1.7321 (θ=60°) in example 2 of the present disclosure;
FIG. 9 is a graph showing initial sliding load and friction coefficient of T-shaped connection nodes of friction type high-strength bolts with different compression shear ratios when the diameter of the bolts is 20mm in example 2 of the present disclosure;
FIG. 10 is a graph showing initial sliding load versus compression-shear ratio for T-shaped connection nodes of friction type high-strength bolts with different friction coefficients when the diameters of the bolts are 20mm in example 2 of the present disclosure;
fig. 11 is a graph of initial sliding load versus initial clamping force for a T-shaped connection node of a friction type high strength bolt at different compression shear ratios for a bolt diameter of 20mm and a friction coefficient of μ=0.4 in example 2 of the present disclosure;
fig. 12 is a graph of initial sliding load versus bolt diameter for a friction type high strength bolt T-shaped connection node at different friction coefficients for a compression shear ratio λ=1.0000 (θ=45°) in example 2 of the present disclosure;
fig. 13 is a graph of initial sliding load versus thickness of a connecting plate for a T-shaped connecting node of a friction type high strength bolt with different friction coefficients when the compression shear ratio λ=1.0000 (θ=45°) in example 2 of the present disclosure;
in the figure, 1, an upper bearing plate, 2, an upper connecting plate, 3, a lower connecting plate, 4, a lower bearing plate, 5, a nut, 6, a high-strength bolt, 7, a bolt hole, 8, a simulated upper bearing plate, 9, a simulated upper connecting plate, 10, a simulated lower connecting plate, 11, a simulated lower bearing plate, 12, a simulated high-strength bolt, 13, a simulated applied load, 14, a simulated fixed constraint, 15, a simulated high-strength bolt clamping force, 16, a simulated connecting plate normal contact, 17, a simulated connecting plate tangential contact, 18, a simulated high-strength bolt and screw outer wall contact with a hole wall, 19, a simulated high-strength bolt and nut contact with a connecting plate normal direction, and 20, a simulated high-strength bolt and nut contact with a connecting plate tangential direction.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;
for convenience of description, the words "upper", "lower", "left" and "right" in the present disclosure, if they mean only that they correspond to the upper, lower, left, and right directions of the drawings themselves, and do not limit the structure, only for convenience of description and simplification of the description, but do not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present disclosure.
As introduced by the background art, the prior art has the defects, in order to solve the technical problems, the application provides a friction type high-strength bolt T-shaped connecting node under the action of a compression shear combination and a design method of the node, so that no design basis is available for a designer.
The method for designing the connection node disclosed in this embodiment is further described below with reference to fig. 1 to 13;
example 1:
the structure of the friction type high-strength bolt connection node bearing the combined action of compression and shear is shown in figures 1-3, and the friction type high-strength bolt connection node comprises an upper bearing plate 1, a lower bearing plate 4, an upper connecting plate 2, a lower connecting plate 3, nuts 5 and high-strength bolts 6 for splicing connecting plates, wherein the bottom of the upper bearing plate 1 is welded and connected with the upper connecting plate 2, the upper connecting plate 2 is obliquely arranged, the connecting plates 2 in the node are specially designed according to the installation angle, different compression and shear ratios can be simulated, and the anti-slip bearing capacity of the connection node under the combined action of different pressures and shearing forces is disclosed. The top of the lower bearing plate 4 is welded and connected with the lower connecting plate 3, the lower connecting plate 3 is parallel to the upper connecting plate 2, the upper connecting plate 2 and the lower connecting plate 3 are tightly attached, the upper bearing plate 1 and the lower bearing plate 4 are vertically arranged, a plurality of bolt holes 7 are formed in the upper connecting plate 2 and the lower connecting plate 3, high-strength bolts 6 are penetrated in the bolt holes 7, the ends of the high-strength bolts 6 are fastened by nuts 5, and the upper connecting plate and the lower connecting plate are fastened and connected; the number and the size of the high-strength bolts 6 are matched with those of the bolt holes 7.
The top of the upper bearing plate 1 is a plane parallel to the horizontal direction, the bottom of the lower bearing plate 4 is a plane parallel to the horizontal direction, and the included angle between the axis of the high-strength bolt 6 and the vertical direction is theta, namely, the included angle between the vertical lines of the upper connecting plate and the lower connecting plate surface and the vertical direction is theta. When bearing load, the top of the upper bearing plate bears vertical load.
Example 2:
the method comprises the steps of firstly designing materials and dimensions of node component members, then simulating the anti-slip bearing capacity of T-shaped connection nodes under different influence parameters by adopting a finite element method, and finally carrying out regression analysis on relational expressions of different parameters and the anti-slip bearing capacity.
The longitudinal sections of the upper bearing plate and the lower bearing plate are quadrilateral, the structures and the sizes of the upper bearing plate and the lower bearing plate are the same, and the size of the upper bearing plate is a multiplied by b multiplied by c multiplied by w multiplied by t 2 Wherein w is the welding length of the upper bearing plate and the upper connecting plate, a, b and c are the dimensions of other three sides respectively, wherein one side c is specially designed into an inclined shape, the main purpose is to ensure that the bearing plate centroid, the bearing surface centroid and the connecting plate centroid are on the same straight line (commonly called as an axis), the load is ensured to be uniformly transmitted to the connecting plate through the bearing plate, and b and c are determined according to the included angle (namely theta) between the axis of the high-strength bolt and the load applying direction and a, wherein a is any dimension which is parallel to the load and does not influence the load application; when the dimension a is determined, an axis vertical line is drawn along the outer end point of the line section a, the length of the vertical line is b/2, the length of the vertical line is prolonged to b, and the length of the line section c is determined by connecting the line section b with the end point of the connecting plate. Different compression-shear ratios can be simulated by changing the size of the bearing plate. t is t 2 B× is the thickness of the upper bearing platet 2 To apply the area of the load F, the materials and dimensions of the two bearing plates are designed so that the load does not exceed the allowable stress, namely F/bt 2 ≥[σ]。
The two connecting plate surfaces are respectively and vertically arranged with the two bearing plate surfaces, and the connecting plate has the size of l multiplied by w multiplied by t 1 Wherein l is connecting plate length, w is connecting plate and bearing plate welded width, and two parameters are confirmed according to the quantity and the arrangement requirement of high strength bolt, and the determination of l length comprises four parts, includes: (1) the distance between the center of the bolt and the edge of the connecting plate; (2) the distance between the center of the bolt and the edge of the bearing plate; (3) bearing plate thickness; (4) The center distance of the bolts, the sum of the center distance and the center distance is in the range of [ (6+3n) l )d 0 +t 2 ，min{(16+16n l )d 0 ,(32+24n l )t 1 }+t 2 ]Between them. The determination of w length is made up of two parts, including: (1) the distance between the center of the bolt and the edge of the connecting plate; (2) The center distance of the bolts, the sum of the center distance and the bolts has the value range of [3d ] 0 (1+n w ),min{(12n w +8)d 0 ,(18n w +16)t 1 }]Between them. n is n l 、n w The spacing number of the bolt rows in the length l and the w directions of the connecting plate are respectively d 0 Is the aperture of the bolt, t 1 The thickness of the connecting plate is not smaller than 16mm, and is not smaller than the diameter of the high-strength bolt.
The method for treating the contact surface of the two connecting plates adopts the same construction technology with the contact surface of the component (the component refers to a steel column or a steel beam of a connecting joint), namely the anti-slip coefficient mu of the friction surface is the same. The anti-slip coefficient of the friction surface of the common steel member is generally between 0.3 and 0.6 according to the treatment method of the contact surface of the connecting plate and the steel grade of the member.
Bolt holes are drilled on the connecting plate according to the number and the specification of the high-strength bolts, and the standard aperture d of the M12 and M16 high-strength bolts 0 Standard bore diameter d of M18, M20, M22 and M24, 1.5mm greater than nominal diameter d of the bolt 0 Standard bore diameter d of M27 and M30, 2.0mm greater than nominal diameter d of the bolt 0 3.0mm larger than the nominal diameter d of the bolt.
The distance between the center of the high-strength bolt and the edge of the connecting plate is divided into an inward force direction and a vertical inward force direction, wherein the inward force direction is the same as the inward force directionAllowable distance of force direction 2d 0 ～4d 0 Or 8t (taking the smaller of the two) and the allowable distance in the vertical internal force direction is 1.5d 0 ～4d 0 Or 8t (take the smaller of the two). The allowable distance between the centers of the outer row of bolts is 3d 0 ～8d 0 Or 12t (taking smaller value), the allowable distance between the centers of the bolts in the middle row is 3d 0 ～16d 0 Or 24t (take a smaller value for both).
The welding between the connecting plate and the bearing plate adopts butt groove welding, and is preferably selected according to the plate thickness and construction conditions of the bearing plate and the connecting plate and the requirements of the related current national standard.
The grade and the model of the high-strength bolt are selected according to the thickness of the connecting plate, the thickness of the bearing plate and the design specification of the high-strength bolt, and the pretightening force is sequentially applied according to the construction specification of the high-strength bolt.
And establishing a solid unit finite element model of the connecting plate, the bearing plate and the high-strength bolt.
And defining parameters of contact, load, friction coefficient and boundary condition of the node model, and calculating the initial sliding load of the node by finite element software.
And regression analysis is carried out to obtain a calculation formula of the anti-slip load and compression shear ratio, the friction coefficient, the bolt pretightening force, the bolt diameter and the thickness of the connecting plate of the T-shaped connecting node of the friction type high-strength bolt.
And designing the anti-sliding bearing capacity of the T-shaped connecting node of the friction type high-strength bolt under the action of the compression-shear combination through a regression calculation formula.
In order to accurately simulate the mechanical properties of the high-strength bolt connection node under the action of the compression-shear combination, the embodiment adopts a three-dimensional entity unit to simulate the bearing plate, the connecting plate and the high-strength bolt, and a finite element model of the T-shaped connection node is built according to the structural form shown in fig. 1, as shown in fig. 4. In order to simplify the calculation, the steel adopts an elastoplastic stress strain curve. According to the embodiment, an accurate finite element model is established according to test results, and the mechanical properties of the T-shaped connecting node are comprehensively researched by changing relevant parameters of the model.
The process for establishing the finite element model of the T-shaped connecting node of the high-strength bolt under the action of the compression-shear combination is as follows:
s1, in order to accurately simulate the mechanical properties of the T-shaped connecting node, according to the sizes shown in fig. 1-3, finite element analysis software is adopted to establish a finite element numerical model of the T-shaped connecting node, and parameter analysis is carried out on different compression-shear ratios, friction coefficients, connecting plate thicknesses and initial bolt pretightening forces as shown in fig. 5 (a), 6 (a), 7 (a) and 8 (a).
S2, during modeling, the bearing plate is made of Q345-level steel, the connecting plate is made of Q235-level steel, the high-strength bolt grade is 10.9, and the material density is 7850kg/m 3 Elastic modulus of 2.06X10 6 The Poisson's ratio was 0.3, and the yield strengths of the bearing plate, the connecting plate and the high-strength bolt were 345MPa, 235MPa and 940MPa, respectively, and the plastic strain of the steel was 0 regardless of the plastic deformation of the material.
S3, when the components are assembled, 4 component examples are created in total, and equiaxial constraint is established between the bolt holes on the connecting plates and the bolt shafts.
S4, in the modeling of the embodiment, two analysis steps are additionally arranged except for the initial analysis step and are respectively used for applying bolt pretightening force and applying displacement boundary conditions, the types of the analysis steps are all static force general, the time length is 1, a geometric nonlinear calculation mode is adopted in calculation, the designated dissipation energy fraction is 0.0002, the maximum increment step number is 10000, the initial increment step size is 0.01, the minimum increment step size is 0.00001, the maximum increment step size is 1, and the two analysis steps both adopt a 'Full Newton' solving technology.
S5, as shown in FIG. 4, the contact in the embodiment mainly comprises the contact between a bolt shaft and a bolt hole wall of the connecting plate, the contact between the surfaces of the two connecting plates and the contact between the bolts and the upper and lower surfaces of the connecting plates. All contact types are surface-to-surface contacts. When contact is defined, the tangential direction is defined as penalty friction, the normal direction is defined as "hard" contact, and separation after surface contact is allowed, wherein the friction coefficient between the two connecting plate surfaces is set in the range of 0.3-0.6 according to the specification, and the friction coefficient between the rest surfaces is 0.2.
S6, in the analysis step 1, pretightening force is applied to the Bolt through a Bolt-Load, the inner surface of the pretightening force is selected as shown in FIG. 4, the application method is force application, and the pretightening force comprises 140kN, 155kN and 170kN.
S7, boundary conditions are as shown in FIG. 4, in the initial analysis step, the degree of freedom of the lower surface of the lower bearing plate 4 is fully constrained, and in the analysis step 2, one displacement constraint is applied to the upper surface of the upper bearing plate 1 along the Z-axis direction, and the displacement is set to be 50mm.
S8, when the grids are divided, the whole embodiment adopts a structure to divide the grids, the unit type is C3D8R, the unit sizes of the bearing plate and the connecting plate are 8mm, and the unit size of the bolt is 3mm.
S9, analyzing the modeling type building operation, and extracting the relative slippage between the connecting plates and the pressure born by the upper surface of the upper bearing plate from the stress cloud chart to finally obtain the initial slippage load (the obtained pressure is the initial slippage load) of the embodiment.
According to the method, finite element numerical analysis models under different compression-shear ratios (1.7321, 1.4281, 1.0000, 0.7002), friction coefficients (0.3, 0.4, 0.5, 0.6), bolt pretightening forces (140 kN, 155kN, 170 kN), connecting plate thicknesses (10 mm, 13mm, 15mm, 18mm, 20 mm) and bolt diameters (16 mm, 20mm, 22 mm) are established.
Regression analysis of the relationship between each different parameter and initial slip load: the relation formula of the initial sliding load and the compression shear ratio, the friction coefficient, the clamping force (namely the bolt pretightening force), the bolt diameter and the thickness of the connecting plate. From the regression result, the compression-shear ratio, friction coefficient and initial sliding load are all nonlinear, and a quadratic curve a+bx+cx can be adopted 2 Fitting, as shown in fig. 9 and 10; the initial clamping force, the bolt diameter and the initial sliding load are in a linear relation, and a linear equation a+bx can be adopted for fitting, as shown in fig. 11 and 12; the web thickness has no effect on the initial slip load as shown in fig. 13.
Assuming that the initial sliding load equation under different clamping force and compression-shear ratio is a 1 +b 1 μ+c 1 μ 2 . Wherein the regression coefficient a 1 、b 1 、c 1 As shown in table 1.
TABLE 1 regression coefficient of initial sliding load and coefficient of friction at different clamping force and compression shear ratios for bolts 20mm in diameter
Assume that the quadratic curve equation of initial sliding load and friction coefficient under different compression-shear ratios and connecting plate thicknesses is a 2 +b 2 μ+c 2 μ 2 . Wherein the regression coefficient a 2 、b 2 、c 2 As shown in table 2.
TABLE 2 regression coefficient of initial sliding load and Friction coefficient at different compression-shear ratios and connecting plate thicknesses when the bolt diameter is 20mm
Assuming that the thickness of the connecting plate is 20mm, the linear equation of the initial sliding load and the bolt diameter under different compression-shear ratios and friction coefficients is a 3 +b 3 D. Wherein D is the diameter of the bolt, regression coefficient a 3 、b 3 As shown in table 3.
TABLE 3 regression coefficients of initial sliding load and bolt diameter at different compression-shear ratios and connecting plate thicknesses when the bolt diameter is 20mm
According to the same modeling method, the relation between any parameter of the compression-shear ratio, the friction coefficient, the clamping force, the bolt diameter and the thickness of the connecting plate and the initial sliding load can be established. When the model is built, the 5 different parameters can be selected for matching, and the accurate regression coefficient in the relation formula of the initial sliding load and each parameter can be calculated through the finite element model and regression analysis.
And designing the anti-sliding bearing capacity of the T-shaped connecting node of the friction type high-strength bolt under the action of the compression-shear combination through a regression calculation formula.
And during theoretical calculation, the initial sliding load is the load when the friction type high-strength bolt connection joint slides for the first time. According to the standard requirements, the friction type high-strength bolt connection joint is regarded as being destroyed once slipping occurs, so that the initial slipping load is the anti-slipping bearing capacity of the connection joint.
When the bearing capacity of the friction type high-strength bolt connecting joint is designed, firstly, according to the design values of 5 parameters of the thickness of the connecting plate, the friction coefficient of the contact surface of the connecting plate, the shearing-pressing ratio, the bolt diameter and the applied clamping force, the regression equations of the anti-slip bearing capacity and the parameters of the connecting nodes in tables 1, 2 and 3 are substituted, and the anti-slip bearing capacity of the nodes is calculated.
The following are illustrated:
the bolt diameter and the connecting plate thickness are 20mm, the friction coefficient of the contact surface of the connecting plate is 0.4, the clamping force is 155kN, the shearing-pressing ratio is 1.0000, the number of the bolt rows along the w direction of the connecting plate is 4, namely 8 high-strength bolts, and the anti-sliding bearing capacity of the connecting node is obtained.
Table 1, clamping force 155kN, shearing ratio 1.0000, corresponding regression coefficient a 1 ＝1712.39；b 1 ＝-8364.20；c 1 12490.40, the anti-sliding bearing capacity of the 4 rows of high-strength bolts is
F＝4×(1712.39-8364.20×0.4+12490.40×0.4 2 )＝1460.69kN。
Similarly, when the anti-slip bearing capacity does not meet the bearing requirement, the design can be performed by modifying 5 parameters until the bearing requirement is met. The actual calculated data size of the invention is larger, and the embodiment only uses part of the actual calculated data size to describe the actual calculated data size, and the design value of the anti-slip bearing capacity of all relevant parameters is not listed completely.
While the specific embodiments of the present disclosure have been described above with reference to the drawings, it should be understood that the present disclosure is not limited to the embodiments, and that various modifications and changes can be made by one skilled in the art without inventive effort on the basis of the technical solutions of the present disclosure while remaining within the scope of the present disclosure.
The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims (8)
1. A design method of a friction type bolt connection node bearing the combined action of compression and shearing is characterized by comprising the following steps:
establishing a finite element model of a connecting plate, a bearing plate and a connecting bolt which are contained in the connecting node;
defining parameters of contact, load, friction coefficient and boundary condition of the finite element model to obtain initial sliding load of the connecting node;
regression analysis is carried out to obtain a relation formula of initial sliding load of the connecting node and connecting node parameters;
designing the anti-slip bearing capacity of the friction type bolt connection node under the combined action of pressure and shear through a regression relation formula;
the process for establishing the finite element model of the T-shaped connecting node of the high-strength bolt under the action of the compression-shear combination is as follows:
establishing a finite element numerical model of the T-shaped connecting node by adopting finite element analysis software, and carrying out parameter analysis on different compression-shear ratios, friction coefficients, connecting plate thicknesses and initial pre-tightening forces of bolts;
when the parts are assembled, equiaxial constraint is established between the bolt holes on the connecting plates and the bolt shafts;
in modeling, two analysis steps are additionally arranged except for the initial analysis step, wherein the two analysis steps comprise an analysis step 1 and an analysis step 2 which are respectively used for applying bolt pretightening force and displacement boundary conditions, the types of the analysis steps are all static force general, the time length is 1, and a geometric nonlinear calculation mode is adopted in calculation;
the contact mainly comprises the contact between a bolt shaft and the wall of a bolt hole of the connecting plate, the contact between the surfaces of the two connecting plates and the contact between the bolt and the upper and lower surfaces of the connecting plates, and all contact types are surface-to-surface contact;
in the analysis step 1, a pretightening force is applied to the bolt, in the initial analysis step, the degree of freedom of the lower surface of the lower bearing plate is fully constrained, and in the analysis step 2, a displacement constraint is applied to the upper surface of the upper bearing plate 1 along the Z-axis direction;
when the grids are divided, the grids are divided by adopting structures;
analyzing the modeling type building operation, extracting the relative slippage between the connecting plates and the pressure born by the upper surface of the upper bearing plate from the stress cloud picture, and finally obtaining the initial slippage load;
the initial sliding load of the connecting node is obtained by the following steps:
defining parameters of contact, load, friction coefficient and boundary condition of a finite element model by the finite element model of a connecting node, establishing full constraint of degree of freedom on the lower surface of a bearing plate positioned at the lower part, applying displacement constraint vertically downwards on the upper surface of the bearing plate positioned at the upper part, analyzing to obtain a stress cloud picture, and further obtaining the relative sliding quantity between two connecting plates and the pressure born by the bearing plate positioned at the upper part, wherein the pressure is the initial sliding load of the connecting node;
the parameters of the connecting node comprise a compression-shear ratio, a friction coefficient, a bolt pretightening force, a connecting bolt diameter and a connecting plate thickness.
2. The method for designing a friction type bolt connection node for bearing the combined action of compression and shear according to claim 1, wherein the number of the connection plates and the number of the bearing plates of the connection node are two, the two connection plates are arranged in a contact manner, each connection plate is connected with one bearing plate, the two connection plates are connected through a connection bolt, after the finite element models of the connection plates, the bearing plates and the connection bolts are built, equiaxial constraint is built between the bolt holes of the connection plates and the connection bolts, and pretightening force is applied to the connection bolts.
3. The compression-shear combined action of claim 1The design method of the friction type bolt connection node is characterized in that the initial sliding load, the compression-shear ratio and the friction coefficient of the connection node are all in nonlinear relation, and a quadratic curve a+bx+cx is adopted 2 Fitting; the initial sliding load of the connecting node and the bolt pretightening force are in linear relation, and linear equation a+bx fitting is adopted; the thickness of the connecting plate has no influence on the initial sliding load.
4. The method for designing a friction type bolting node bearing the combined action of pressure and shear according to claim 1, wherein the value of the parameter of the bolting node is substituted into the relation formula of the initial sliding load and the parameter of the bolting node to obtain the initial sliding load of the bolting node, namely the anti-sliding bearing capacity of the bolting node.
5. The method of claim 4, wherein the method comprises determining whether the anti-slip bearing capacity of the connection node meets the bearing requirement, and if not, modifying the connection node parameters until the connection node meets the bearing requirement.
6. A design system for a friction type bolting node subjected to a combination of compression and shear comprising:
the model building module is used for building a finite element model of the connecting plate, the bearing plate and the connecting bolt which are contained in the connecting node;
the definition module is used for defining contact, load, friction coefficient and boundary condition parameters of the finite element model to obtain initial sliding load of the connecting node;
the analysis module is used for regression analysis of a relation formula of the initial sliding load of the connection node and the connection node parameter;
the design module is used for designing the anti-slip bearing capacity of the friction type bolt connection node under the action of the compression-shear combination through a regression relation formula;
the process for establishing the finite element model of the T-shaped connecting node of the high-strength bolt under the action of the compression-shear combination is as follows:
establishing a finite element numerical model of the T-shaped connecting node by adopting finite element analysis software, and carrying out parameter analysis on different compression-shear ratios, friction coefficients, connecting plate thicknesses and initial pre-tightening forces of bolts;
when the parts are assembled, equiaxial constraint is established between the bolt holes on the connecting plates and the bolt shafts;
in modeling, two analysis steps are additionally arranged except for the initial analysis step, wherein the two analysis steps comprise an analysis step 1 and an analysis step 2 which are respectively used for applying bolt pretightening force and displacement boundary conditions, the types of the analysis steps are all static force general, the time length is 1, and a geometric nonlinear calculation mode is adopted in calculation;
the contact mainly comprises the contact between a bolt shaft and the wall of a bolt hole of the connecting plate, the contact between the surfaces of the two connecting plates and the contact between the bolt and the upper and lower surfaces of the connecting plates, and all contact types are surface-to-surface contact;
in the analysis step 1, a pretightening force is applied to the bolt, in the initial analysis step, the degree of freedom of the lower surface of the lower bearing plate is fully constrained, and in the analysis step 2, a displacement constraint is applied to the upper surface of the upper bearing plate 1 along the Z-axis direction;
when the grids are divided, the grids are divided by adopting structures;
analyzing the modeling type building operation, extracting the relative slippage between the connecting plates and the pressure born by the upper surface of the upper bearing plate from the stress cloud picture, and finally obtaining the initial slippage load;
the initial sliding load of the connecting node is obtained by the following steps:
defining parameters of contact, load, friction coefficient and boundary condition of a finite element model by the finite element model of a connecting node, establishing full constraint of degree of freedom on the lower surface of a bearing plate positioned at the lower part, applying displacement constraint vertically downwards on the upper surface of the bearing plate positioned at the upper part, analyzing to obtain a stress cloud picture, and further obtaining the relative sliding quantity between two connecting plates and the pressure born by the bearing plate positioned at the upper part, wherein the pressure is the initial sliding load of the connecting node;
the parameters of the connecting node comprise a compression-shear ratio, a friction coefficient, a bolt pretightening force, a connecting bolt diameter and a connecting plate thickness.
7. The connection node designed by the design method for the friction type bolt connection node under the combined action of the pressure shear according to any one of claims 1 to 5, which is characterized by comprising an upper bearing plate, a lower bearing plate, an upper connecting plate, a lower connecting plate and connecting bolts, wherein the bottom of the upper bearing plate is fixedly connected with the upper connecting plate, the upper connecting plate is obliquely arranged, the top of the lower bearing plate is fixedly connected with the lower connecting plate, the lower connecting plate is parallel to the upper connecting plate, the upper connecting plate and the lower connecting plate are closely arranged, the upper bearing plate and the lower bearing plate are vertically arranged, a plurality of bolt holes are formed in the upper connecting plate and the lower connecting plate, the connecting bolts penetrate through the bolt holes, and the upper connecting plate and the lower connecting plate are fixedly connected by the connecting bolts.
8. The connecting joint as set forth in claim 7, wherein the top of said upper bearing plate is a plane parallel to the horizontal, the bottom of said lower bearing plate is a plane parallel to the horizontal, an angle is formed between the axis of the connecting bolt and the vertical plane, and the two plate surfaces of said connecting plate are respectively perpendicular to the plate surfaces of said two bearing plates.
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| CN110610063A (en) * | 2019-10-21 | 2019-12-24 | 山东泰开高压开关有限公司 | Method for determining whether bolt type selection is correct |
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| CN106295024B (en) * | 2016-08-15 | 2019-10-01 | 北京航空航天大学 | A kind of compound material bolt connection load distribution calculation method considering gap and frictional influence |
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| CN110610063A (en) * | 2019-10-21 | 2019-12-24 | 山东泰开高压开关有限公司 | Method for determining whether bolt type selection is correct |
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