KR101384549B1 - Method and apparatus for judging ultimate strength reduction in channel bolted connection with curling - Google Patents

Abstract

The present invention predicts the maximum strength pattern and the out-of-plane deformation behavior of one-side shear bolts of austenitic stainless steel (STS304) c-section steel by finite element analysis, and the maximum strength drop according to out-of-plane deformation. The present invention relates to a method and apparatus for determining the maximum strength drop due to out-of-plane deformation of a bolted joint of an austenitic stainless steel U-shaped steel that can be predicted.
Method for determining the maximum strength according to the out-of-plane deformation (Curling) of the bolted joint according to the present invention, the first step of building a finite element analysis model of the bolted joint; A second step of inputting a variable for the finite element analysis model constructed in the first step; A third step of performing modeling on the finite element analysis model constructed based on the input variable; A fourth step of outputting a result value modeled in the third step; And a fifth step of determining a decrease in the maximum strength based on the result value.

Description

METHOD AND APPARATUS FOR JUDGING ULTIMATE STRENGTH REDUCTION IN CHANNEL BOLTED CONNECTION WITH CURLING}

The present invention relates to a method of determining the maximum strength drop due to the out-of-plane deformation of the bolted joint, more specifically, the one-side shear bolted joint of austenitic stainless steel (STS304) c-shaped steel using a finite element analysis method Determination of maximum strength drop due to out-of-plane deformation of bolted joints of austenitic stainless steel U-shaped steels to predict the maximum strength pattern and out-of-plane deformation behavior according to the load direction edge distance It relates to a method and a judging device.

Cold-formed steel (thin plate) is manufactured in various cross-sectional shapes by processing steel sheet at room temperature or low temperature, and it is lighter than hot rolled steel (thick plate), and it is easy to join and assemble. Doing.

In the case of cold-formed steel, most of them are thin plate members, and bolt joining is easy. The cold-formed stainless steel has a long shear direction and a perpendicular load direction at one-stage flat plate bolted joint, so that not only in-plane fracture but also out-of-plane deformation occurs in plate thickness direction. Can affect

Therefore, it is necessary to investigate the structural behavior of bolted joints, the mechanism of occurrence of out-of-plane deformation and the effect of out-of-plane deformation on the strength of the joint.

In connection with the technique of predicting the breakage of a thin bolt joint using finite element analysis, JP-A-10-2008-0090551 relates to a failure prediction method, and to evaluate the breakage limit of a thin plate made of a metallic material. Techniques for predicting the occurrence of breakage using an analysis method have been disclosed.

In addition, Korean Patent Laid-Open Publication No. 10-2009-0112369 relates to a method for measuring a stress-strain relationship in a microstructure, and includes a load and displacement calculated by performing finite element analysis and a calculated load and an experimentally measured load. And a technique for measuring the stress-strain relationship by comparing the displacements.

However, in the prior art as described above, by measuring the fracture and deformation of the structure by performing a finite element analysis, it is not possible to predict the maximum strength drop in the occurrence of out-of-plane deformation depending on the plate thickness and the load direction edge distance to the bolted joint. There is a problem.

The present invention has been made to solve the problems as described above, using the finite element analysis method in the out-of-plane deformation for the bolted joint that can grasp the behavior of the maximum strength, fracture patterns and out-of-plane deformation in stainless steel c-section steel bolted joint The purpose of the present invention is to provide a determination method and a determination device of the maximum strength drop according to the present invention.

In addition, the present invention by building a finite element analysis model of the bolted joints for austenitic stainless steel c-shaped steel, the out-of-plane deformation and the out-of-plane deformation according to the edge length at the austenitic bolted joint of stainless steel c-shaped steel The purpose of the present invention is to provide a method and apparatus for determining the maximum strength drop due to out-of-plane deformation of a bolted joint which can predict the effect on the maximum strength.

However, the object of the present invention is not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the determination method of the maximum strength according to the out-of-plane deformation (Curling) of the bolted joint according to the present invention, the first step of building a finite element analysis model of the bolted joint; A second step of inputting a variable for the finite element analysis model constructed in the first step; A third step of performing modeling on the finite element analysis model constructed based on the input variable; A fourth step of outputting a result value modeled in the third step; And a fifth step of determining a decrease in the maximum strength based on the result value.

In addition, the method of determining the maximum strength according to the present invention, the finite element analysis model of the bolted joint to be constructed in the first step is a dimension, material properties, a bolt array of m rows n columns for austenitic stainless steel c-shaped steel, It characterized in that it comprises a bolt hole diameter, pitch, gauge. Where m and n are natural numbers.

In addition, the method of determining the maximum strength according to the present invention is characterized in that the variable input in the second step is a load direction podium distance.

In addition, the method of determining the maximum strength according to the present invention is characterized in that the modeling for the finite element analysis model performed in the third step is performed using a nonlinear analysis method.

In addition, the method of determining the maximum strength according to the present invention, the modeling for the finite element analysis model performed in the third step is characterized in that the large deformation function (NLGEOM = YES) is set.

In addition, the method of determining the maximum strength according to the present invention, the modeling for the finite element analysis model performed in the third step is characterized in that the reduced integral hexahedral solid element (C3D8R) is applied.

In addition, the method of determining the maximum strength according to the present invention, the modeling of the finite element analysis model in the third step, the maximum strength (P _ua ) and the out-of-plane for the condition that does not restrain the occurrence of out-of-plane deformation at the bolted joint It is characterized by calculating the maximum proof _force (P _uaR ) for the condition that restrains the occurrence of deformation.

In addition, the method of determining the maximum strength according to the present invention, the modeled result value output in the fourth step is characterized in that it comprises at least one of the fracture form, the maximum strength and the out-of-plane deformation for the bolted joint.

In addition, the method of determining the maximum bearing strength according to the present invention is characterized in that the fracture shape includes a tensile failure in the direction perpendicular to the load in the bolted joint and a longitudinal failure in the load direction.

In addition, in the method of determining the maximum strength according to the present invention, in the fifth step, the determination of the decrease in the maximum strength is based on the maximum condition for not restraining the occurrence of the out-of-plane deformation when out-of-plane deformation occurs in the modeling result. It is characterized in that it is predicted by the ratio of the maximum strength (P _uaR ) to the conditions that restrain the occurrence of the internal strength (P _ua ) and out-of-plane deformation.

According to an aspect of the present invention, there is provided a apparatus for determining a maximum strength according to out-of-plane deformation of a bolted joint, comprising: a finite element analysis model building module for constructing a finite element analysis model of the bolted joint through shape information about the bolted joint; A variable input module for inputting a main variable for the bolt joint; An analysis model modeling module for performing modeling on the finite element analysis model constructed based on the inputted main variables by a nonlinear analysis method; An output module for outputting a modeled result value; And a load reduction determination module for determining a drop in the maximum strength of the bolted joint based on the modeled result value outputted through the output module.

In addition, the apparatus for determining the maximum strength according to the present invention, the shape information for the bolted joint is characterized in that the dimensions, material properties, bolt array of m rows n columns, bolt hole diameter, pitch, gauge for austenitic stainless steel c-shaped steel And the main variable is the load direction podium distance. Where m and n are natural numbers.

In addition, the apparatus for determining the maximum strength according to the present invention, the analysis model modeling module is a condition for restraining the maximum strength (P _ua ) and the occurrence of out-of-plane deformation for the condition that does not restrain the occurrence of out-of-plane deformation at the bolted joint Calculates the maximum strength (P _uaR ), and the strength reduction judgment module, when the out-of-plane deformation occurs in the modeling result value, the maximum strength (P _ua ) and out-of-plane deformation for the condition that does not restrain the occurrence of the out-of-plane deformation The decrease in the maximum strength is characterized by the ratio of the maximum strength ( _PuaR ) to the conditions that restrain the occurrence of.

According to the determination method and the determination device of the maximum strength drop according to the out-of-plane deformation of the bolted joint of the present invention, there is an advantage that the finite element analysis method can determine the behavior of the maximum strength, fracture patterns and out-of-plane deformation at the bolted joint.

In addition, according to the present invention, by building a finite element analysis model of the bolted joints for austenitic stainless steel U-shaped steel, the out-of-plane deformation and the out-of-plane deformation of the abutment distance in the bolted joint of stainless steel U-shaped steel There is an advantage to predict the effect of the occurrence on the maximum strength.

In addition, according to the present invention, by comparing the maximum strength predicted by the determination method and the determination device of the maximum strength drop due to the out-of-plane deformation of the bolted joint and the predicted strength by the current standard expression, the influence of the fracture shape and the out-of-plane deformation There is an advantage to suggest a new strength formula.

1 is a block diagram showing a maximum strength determination apparatus according to the out-of-plane deformation of the bolted joint of the present invention.
2 is an exemplary view showing a finite element analysis model of a bolted joint constructed in accordance with the present invention.
3 is a flowchart illustrating a method of determining the maximum strength according to the out-of-plane deformation of the bolted joint of the present invention.
4 is an exemplary view showing a fracture shape in the test results of the test body.
FIG. 5 is an exemplary diagram illustrating a fracture pattern and a stress distribution of a result modeled by a bolt array of two rows and one column. FIG.
6 to 10 are exemplary diagrams illustrating fracture patterns and stress distributions of experimental results and modeled results in a bolt array of two rows and two columns.
FIG. 11 is an exemplary diagram showing a load-displacement curve of the resultant modeled in the bolt arrangement of two rows and one column. FIG.
12 is an exemplary diagram showing a load-displacement curve of the results modeled in the bolt array of two rows and two columns.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description of preferred embodiments of the present invention will be given with reference to the accompanying drawings. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Embodiments in accordance with the concepts of the present invention can make various changes and have various forms, so that specific embodiments are illustrated in the drawings and described in detail in this specification or application. It is to be understood, however, that it is not intended to limit the embodiments according to the concepts of the present invention to the particular forms of disclosure, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, the terms "comprises ",or" having ", or the like, specify that there is a stated feature, number, step, operation, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

1 is a block diagram showing a maximum strength determination apparatus according to the out-of-plane deformation of the bolted joint of the present invention.

As shown, the maximum strength determination device 1 according to the out-of-plane deformation of the bolted joint of the present invention is a finite element analysis model building module 10, variable input module 20, analysis model modeling module 30, output module 40 and the load reduction determination module 50 may be included.

The finite element analysis model building module 10 provides shape information about the bolted joint of the austenitic stainless steel U-shaped steel, for example, dimensions of the steel, material properties (for example, von Mises yield criterion and isometry). Elastomeric material to which the hardening rule applies, including m rows and n columns of bolt arrays (for example, 2 rows 1 row, 2 rows 2 columns, etc.), bolt hole diameter, pitch for rows in the bolt array, and gauges for columns. The finite element analysis model of the bolted joint may be constructed based on the shape information, and the variable input module 20 may input a podium distance that changes in the load direction as a main variable for the bolted joint.

The analysis model modeling module 30 may perform modeling using a nonlinear analysis method based on the finite element analysis model of the bolted joint constructed through the finite element analysis model building module 10 and the input load direction edge distance. At this time, the analysis model modeling module 30 has a large deformation function (NLGEOM = YES) is set to take into account the geometric nonlinearity when modeling, and reduced integral hexahedral solid element including an hourglass control function to prevent excessive deformation (C3D8R) may be applied.

FIG. 2 is an exemplary view showing an example of a finite element analysis model of bolted joints of two rows and two columns constructed. FIG. As shown in Fig. 2, the finite element analysis model of the bolted joint is shown in each bolt disposed on the plate, although not specifically shown, the bolt body without thread on the shear end face (bolt wall contact surface of the bolt) of the bolt ( The bolt hole wall can be configured to be in contact with the shank portion, and the effects of the bolt tension and the friction force between the plate and the plate and the plate plate are not considered.

In addition, to reflect the nonlinear analytical model, we adopt a elasto-plastic material model to which the von Mises yield criterion and the isotropic hardening law are applied, and the material data is the nominal stress-nominal strain (σ _n -ε _n ). The value is converted into true stress-true strain (σ _t -ε _t ) considering the change in the cross-sectional area of the tensile specimen in the load direction and the load perpendicular direction, and the plastic behavior after the elastic region is totally deformed according to the following equation. Enter the plastic strain (ε _pl ) by subtracting the elastic strain (ε _et ) from the figure (ε _t ).

Here, E represents an elastic modulus.

The output module 40 outputs the modeled result value including the model of the result modeled through the analysis model modeling module 30, for example, the fracture shape, the maximum strength and the out-of-plane deformation of the bolted joint, In the case of strength, the analysis model modeling module 30 calculates the maximum strength (P _ua ) for the conditions that do not restrain the occurrence of out-of-plane deformation and the maximum strength (P _uaR ) for the conditions that restrain the out-of-plane deformation. Each may be calculated and output through the output module 40.

The load reduction determination module 50 determines the fall of the maximum strength of the bolted joint based on the modeled result value output through the output module 40. When the out-of-plane deformation occurs in the modeling result value, the out-of-plane deformation The _fall of the maximum strength can be judged by the ratio of the maximum strength (P _ua ) for the condition that does not restrain the occurrence of, and the maximum strength (P _uaR ) for the condition that restrains the out-of-plane deformation.

The maximum strength determination method according to the out-of-plane deformation of the bolted joint is described in detail with reference to FIG.

1 and 3, the finite element analysis model building module 10 constructs a finite element analysis model of the bolted joint (S101). The finite element analysis model includes shape information on the bolted joints of austenitic stainless steel (STS304) angle steel, for example, dimensions, material characteristics (such as von Mises yield criteria and isotropic hardening) for steel steel. Elastoplastic material to which the law applies), the bolt array of m rows and n columns (m and n are natural numbers, for example, 2 rows 1 column, 2 rows 2 columns, etc.), bolt hole diameter, pitch for rows in the bolt array And gauges for heat, and the like.

Thereafter, as the main variable through the variable input module 20, the podium distance in the load direction is input (S102). The analysis model modeling module 30 performs modeling using a nonlinear analysis method based on the constructed finite element analysis model and the inputted main variables (S103). The analytical model modeling module 30 may calculate the maximum strength (P _ua ) for the conditions that do not restrain the occurrence of out-of-plane deformation and the maximum strength (P _uaR ) for the conditions that restrain the out-of-plane deformation. have.

After modeling is performed according to the edge distance, the modeled results (e.g., fracture patterns such as tensile failure in the direction perpendicular to the load direction and longitudinal fracture in the load direction, and the presence of maximum strength and out-of-plane deformation, etc.) Is output through the output module 40 (S104).

The load reduction determination module 50 checks whether out-of-plane deformation occurs in the modeling result output through the output module 40 (S105), and when out-of-plane deformation occurs, the condition for not restraining the out-of-plane deformation occurs. strength is determined a decrease in the maximum strength of the out-of-plane variations in the ratio of the ultimate strength (P _uaR) to (P _ua) and conditions for restraining the occurrence of an out-of-plane deformation (S106).

As described above, according to the present invention by building and modeling the finite element analysis model of the bolted joint of the austenitic stainless steel c-shaped steel, the out-of-plane deformation according to the edge length in the bolt joint of the austenitic stainless steel c-shaped steel and It is possible to predict the effect of out-of-plane deformation on the maximum strength.

[Experimental Example 1]

In Experiment 1, in order to investigate the final behavior according to the variable at the C-shaped bolt joint using austenitic stainless steel, the C-shaped steel 150 × 75 × 75 × 6 having 2 rows and 1 rows and 2 rows and 2 rows of bolt arrays The test specimen of was produced. Bolt diameter (d) is 16mm, bolt hole diameter (Ø) is fixed at 17mm, pitch (p) and gauge (g) at 48mm, and the main direction of the load direction edge distance (e) is 24mm, 36 It changed to mm, 48 mm, and 60 mm.

The specimen name is, for example, C4T6H150E24, where C is a channel, 4 is a row of 2 rows and 2 columns of bolts, T is the thickness of the specimen, H is the diameter of the beam (150 × 75 × 75), and E is the load direction edge length. do. In Experimental Example 1, a simple tensile test was performed with a universal testing machine of 2000kN.

4 (a) to (b) is an exemplary view showing a fracture shape in the experimental results of the test body, the test results of the test body is shown in Table 1 in detail.

[Table 1]

(A) of FIG. 4 shows a pore distance of 24 mm in a two-row, one-column array, and (b) shows 36 mm. FIG. 5 (a) to (d) shows a podium distance of a two-row, two-column bolt arrangement. 24 mm, 36 mm, 48 mm, and 60 mm are shown, respectively.

As shown in Figures 4, 5 and Table 1, all specimens showed block shear fracture (BS), and specimens of C2T6H150E24 showed longitudinal fracture, and bolts for C2T6H150E36 and C2T6H150E48 specimens. Broke.

For the two-row, two-column bolted array, the C4T6H150E24 and C4T6H150E36 specimens with relatively short pore distances had typical block shear failures (net tensile failure + longitudinal shear failure), and the C4T6H150E48 and C4T6H150E60 specimens with relatively long edge lengths. Block shear failure with deformation was observed.

In C4T6H150E60, out-of-plane deformation was found to be the cause of lowering the maximum strength of the section steel bolted joint. However, in the case of C4T6H150E48, the out-of-plane deformation did not significantly affect the maximum strength of the specimen, and the out-of-plane deformation progressed after the maximum strength was determined by tensile failure, which did not significantly affect the maximum strength.

6 and 7 show the load-displacement curves for each specimen (C2T6H150E24, C2T6H150E36, C2T6H150E48, C4T6H150E24, C4T6H150E36, C4T6H150E60). As shown, it can be seen that the strength and stiffness of the deterioration due to the out-of-plane deformation occurs.

[Experimental Example 2]

In Experimental Example 2, the finite element analysis model according to the present invention was used to determine the maximum strength according to the out-of-plane deformation of the bolted joint. In Experimental Example 2, the same variable conditions and shape information as in Experimental Example 1 were used.

8 and 9 are exemplary diagrams showing the stress distribution by the result of modeling the finite element analysis model.

(A) of FIG. 8 shows a pore length of 24 mm, (b) of 36 mm, and (c) of 48 mm in a two-row, one-row bolt arrangement, and FIG. 9 (a) of a two-row, two-row bolt arrangement. The pore length is 36 mm, (b) is 48 mm, and (c) is 60 mm.

In order to investigate the effect of out-of-plane deformation on the maximum strength of the joint at the joints of the t-section bolts, two types were determined according to the constraint of the thickness deformation of the bolt plate in the analytical model.

The analysis model does not constrain the deformation in the thickness direction (outside plane deformation) and the analysis model in which the thickness direction is constrained. In the case of the restraint model, the displacement of the thickness of the bolt plate except the support end is restrained in the analysis.

In FIGS. 8A to 8C, the same analysis results were shown without out-of-plane deformation at the bolted joints as in Experimental Example 1. FIG.

In addition, in the case of two rows and two columns of FIG. 9, it can be seen from (a) that stress concentration is generated between the support column side bolt rows in the load perpendicular direction and on the bolt line in the load direction from the stress distribution at the point of maximum strength.

In FIG. 9C, unlike FIG. 9A, stress concentration is generated between the row of bolts on the support end side and around the bolt in the load direction edge. 9 (b), it can be seen that the stress distribution at the maximum strength time point is different from that of (c). That is, the stress concentration in the tension section of the bolt row far from the load direction edge was shown, and as the displacement increased, the stress concentrated on the bolt line in the load direction edge.

Table 2 compares the maximum strength, fracture type, whether out-of-plane deformation occurs as in Experimental Example 1, and showed a maximum strength of the non-constrained model (P _uaR) and non-binding model (P _ua).

[Table 2]

As shown in Table 2, the maximum strengths of the analysis results (Experimental Example 2) and the experimental results (Experimental Example 1) showed good correspondences in the range of 0.83 to 1.06 (average: 0.96). The same result appeared.

10 to 16 are exemplary diagrams showing a load-displacement curve relationship between an out-of-plane deformation constraint model (add 'R' character) and a non-restraint model of the finite element analysis model.

In the case of the restraint model and the non-restraint model of 2 rows 1 column of FIGS. 10 to 12, the load-displacement curves were the same. In the case of two rows and two columns of FIGS. 13 to 14, the load-displacement curves were shown that the edge distances of 24 mm and 36 mm (C4T6H150E24 and C4T6H150E36) did not occur out of plane deformation. The curves of the restraint model and the non-restraint model were the same, and were also consistent in terms of maximum strength as shown in Table 2 (P _ua / P _uaR = 1.00).

As shown in FIG. 15, the load-displacement curves of the out-of-plane deformation constraint model and the non-restraint model were nearly identical to those of the typical block shear failure pattern, as shown in FIG. 15. The maximum strength ratio (P _ua / P _uaR ) of the restraint model and the non-restraint model was 0.99, indicating no significant difference in the maximum strength.

However, in the case of C4T6H140E60, as shown in FIG. 16, it can be seen that the curve of the restraint model C4T6H140E60R exceeds the curve of the non-restraint model, and the yield strength further increases. In addition, in Table 2, the maximum _yield ratio (P _ua / P _uaR ) is 0.93, which indicates that the maximum _yield decreased by 7% due to the out-of-plane deformation.

On the basis of the validity of the test results and the analytical results, an additional variable analysis was performed for the load direction pore distance (e). In order to investigate the occurrence of out-of-plane deformation, 2 rows and 2 columns were additionally modeled in units of 6 mm based on the 48 mm edge length. From 60 mm, additional modeling was carried out in units of 3 mm to determine the strength drop due to out-of-plane deformation. Was performed.

In the case of 2 rows and 1 columns, modeling was carried out in 6mm units as in 2 rows and 2 columns. In order to investigate the point of out-of-plane deformation affecting the strength, it was judged that the strength decreased at the podium distance similar to 2 rows and 2 columns. Further modeling was performed from mm to 72 mm in 3 mm increments.

Table 3 shows the maximum strength, the maximum strength displacement, the fracture shape, and the occurrence of out-of-plane deformation of models without fixing out-of-plane deformation and fixed models.

[Table 3]

As shown in Table 3, in the case of two rows and two columns, out-of-plane deformation occurred when the load direction edge distance was more than 48mm, and the analytical model of more than 60mm showed the strength drop due to out-of-plane deformation.

On the other hand, in the case of 2 rows and 1 column, out-of-plane deformation occurred when it was 54 mm or more, but unlike the 2 rows and 2 columns, there was no decrease in the maximum strength. In addition, modeling was performed for 78mm and 84mm in order to investigate the load directional joint distance in which the load capacity is degraded due to out-of-plane deformation in the bolt array of 2 rows and 1 column. Although not shown in the figure, the pore length decreased from 78mm or more due to out-of-plane deformation, and showed a 4% and 5% reduction in strength, respectively.

[History Evaluation Formula]

Out-of-plane deformation is expected to be caused by buckling of the plate in the compression zone due to the pressure stress behind the bolt. In the case of bolt joints, KSSC (2009) estimates the maximum pore distance less than 12 times the plate thickness or less than 150 mm. Therefore, analysis was performed up to 72 mm in the direction of load direction. An additional analysis was performed to investigate the drop in strength due to out-of-plane deformation (e = 78 mm, 84 mm).

In addition, in the case of block shear failure accompanied by out-of-plane deformation, the effective load direction of the load direction required for estimating the shear strength after shear failure in the perpendicular direction of the load was evaluated.

In the case of 2 rows and 2 columns, out-of-plane deformation occurred when the load direction end distance was more than 48 mm, and the out-of-plane deformation occurred in more than 60 mm. Withdrawal of strength was over 78 mm.

It can be determined that the stress on the acupressure stress caused by the bolt arrangement is different in the flat plate to which the bolt is bonded. Due to the effect of acupressure stress acting on the back of the bolt at the bolted joint, it is judged that the internal force is not transmitted to the end of the load direction, and shear failure does not occur to the edge along with the out-of-plane deformation.

로 치환하고, AIJ(일본건축학회) 기준에서 언급한 연단거리 제한치 개념을 적용하여 13t로 하중방향연단거리(e)를 제안한다. 또한, SEI/ASCE(미국토목학회) 기준에서 순단면 인장파단의 σ_t의 r개념을 적용하여 다음과 같이 면외변형이 발생한 2행1열과 2행2열 ㄷ형강 볼트접합부의 내력식을 제안할 수 있다.And based on the Mises yield theory, shear stress is calculated in the calculation of the longitudinal shear and block shear fracture strength.

Subsequently, we propose the load direction joint distance (e) to 13t by applying the concept of the pore distance limit mentioned in the AIJ standard. Also, by applying the r concept of σ _t of net section tensile failure in the SEI / ASCE (American Society of Civil Engineers), the strength formula of 2 row 1 column and 2 row 2 column c-section bolt joints where out-of-plane deformation occurred can be proposed. Can be.

Where e3 = Min (e, 13t · r), r is the ratio of the proof force delivered by the bolt to the total tensile force (r = 1 in 2 rows 1 column, r = 1/2 in 2 rows 2 columns), t is the thickness of the plate, sigma _u is the tensile strength of the base material, b is the perpendicular distance in the load direction, and Ø is the diameter of the bolt hole.

Table 4 below shows the result of comparing the block shear strength P _up predicted by the above equation with the maximum shear strength P _ua of the analysis result for the bolted joint in which the out-of-plane deformation occurred.

[Table 4]

The maximum strength ratio (P _up / P _ua ) of the proposed formula for the analysis maximum strength (finite element analysis model) is 0.99 for 2 rows and 2 columns and 0.95 for 2 rows and 1 columns. It can be seen that the accuracy of the prediction is improved than the predicted strength ratio.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. will be. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

10: finite element analysis model construction module 20: variable input module
30: analysis model modeling module 40: output module
50: load capacity determination module

Claims (18)

In the determination method of the maximum strength according to the out-of-plane deformation of the bolted joint,
A first step of constructing a finite element analysis model of the bolted joint;
A second step of inputting a variable for the finite element analysis model constructed in the first step;
A third step of performing modeling on the finite element analysis model using a nonlinear analysis method based on the variable input in the second step;
A fourth step of outputting a result value modeled in the third step; And
And a fifth step of determining a drop in the maximum strength of the bolted joint based on the result value output in the fourth step.
The finite element analysis model of the bolt joint constructed in the first step includes dimensions, material properties, bolt arrays in m rows and n columns (where m and n are natural numbers) for austenitic stainless steel U-shaped steels, and bolt hole diameters. , Pitch, gauges,
The variable input in the second step is a load direction podium distance,
Modeling of the finite element analysis model performed in the third step is a large deformation function (NLGEOM = YES) is set, a reduced integral hexahedral solid element (C3D8R) is applied, do not restrain the occurrence of out-of-plane deformation at the bolted joint ultimate strength for that condition (P _ua) and calculate the maximum strength (P _uaR) for the conditions for restraining the occurrence of an out-of-plane deformation, and
The modeled result value output in the fourth step includes a fracture shape, a maximum strength, and an out-of-plane deformation of the bolted joint, wherein the fracture pattern is a block shear failure, and tensile failure in a direction perpendicular to the load at the bolted joint and Including end fracture in the direction of loading,
In the fifth step, the determination of the decrease in the maximum strength is to restrain the occurrence of the maximum strength (P _ua ) and the out-of-plane deformation for the condition that does not restrain the occurrence of the out-of-plane deformation when the out-of-plane deformation occurs in the modeled result. Judging by the ratio of the maximum strength (P _uaR ) to the conditions to
Wherein after Step 5, the occurrence of an out-of-plane deformation is c-beams block shear strength of the bolt connection (P _up), and then the calculation by the block shear fracture evaluation formula, the block shear strength (P _up) and the out-of-plane deformation occurs using the ratio (P _up / P _ua) of the maximum strength (P _ua) for a condition that does not bound out-of-plane of the bolt connection according to claim 1, further comprising the step of determining a decrease in the maximum strength for the bolt connection How to determine the maximum strength according to the deformation.

Where A _nt is the net cross-sectional area of tensile resistance, A _gv is the total cross-sectional area of shear resistance, σ _u is the tensile strength of the base material, b is the longitudinal direction of the load, Ø is the bolt hole diameter, t is the plate thickness, and e ₃ is the outer No longer increases in strength due to out-of-plane deformation in the distance (e) from the center of the bolt to the load direction edge (r) and in the ratio (r) of the strength delivered by the bolt to the total tensile strength If the value is higher than the limit value, the smaller of the value multiplied by 13 times (13t) of the thickness reflecting the internal load converges to a constant value, that is, e ₃ = Min (e, 13t · r), r is 2 rows 1 column Where r = 1, in row 2 and row 2, r = 1/2, p is the pitch between two bolt centers in the load direction)

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