CN113505508B - Method for applying initial defects of rod piece in direct analysis method - Google Patents
Method for applying initial defects of rod piece in direct analysis method Download PDFInfo
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- CN113505508B CN113505508B CN202110751937.2A CN202110751937A CN113505508B CN 113505508 B CN113505508 B CN 113505508B CN 202110751937 A CN202110751937 A CN 202110751937A CN 113505508 B CN113505508 B CN 113505508B
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- 230000007547 defect Effects 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000004458 analytical method Methods 0.000 title claims abstract description 15
- 239000013598 vector Substances 0.000 claims abstract description 27
- 230000005484 gravity Effects 0.000 claims description 4
- 238000003556 assay Methods 0.000 claims 1
- 230000009466 transformation Effects 0.000 claims 1
- 229910000831 Steel Inorganic materials 0.000 abstract description 6
- 239000010959 steel Substances 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 5
- 238000005452 bending Methods 0.000 description 2
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- VAOCPAMSLUNLGC-UHFFFAOYSA-N metronidazole Chemical compound CC1=NC=C([N+]([O-])=O)N1CCO VAOCPAMSLUNLGC-UHFFFAOYSA-N 0.000 description 2
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- 238000010276 construction Methods 0.000 description 1
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- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
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- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/13—Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
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Abstract
The invention provides a method for applying initial defects of a rod piece in a direct analysis method, and relates to a steel structure direct analysis method. The method comprises the following steps: judging the rod type after obtaining rod units in a model, wherein the model is a three-dimensional entity finite element model established in finite element software SAP 2000; based on the rod type, performing angle adjustment on the rod unit with the local shaft rotation; setting a defect direction and an offset vector of the rod unit based on the rod type; the method for applying the initial defects of the rod piece in the direct analysis method can conveniently and rapidly apply the initial defects to the rod piece, and is simple to operate and good in interactivity.
Description
Technical Field
The invention relates to a direct analysis method of a steel structure, in particular to a method for applying initial defects of a rod piece in a design soft piece by using the direct analysis method.
Background
The direct analysis method in the steel structure design introduces initial defects of the whole and the rod piece in the structural mechanical model, and the initial defects of the structure and the component are required to be considered in the mechanical model. The overall initial defect of the structure is caused by construction errors and overall initial inclination. The initial geometric defect mode of the whole structure can be adopted according to the lowest-order buckling mode. As shown in fig. 3-4, the maximum value Δ0 (fig. 3) of the initial geometric defect representative of the overall frame and support structure may be taken as H/250, H being the overall height of the structure. The initial geometrical defect representative of the whole frame and support structure can also be determined according to formula (5.2.1-1) (fig. 4 (a)); or may be equivalently considered by applying a hypothetical horizontal force at the top of each layer, which may be calculated as per equation (5.2.1-2), the direction of application should take into account the least favorable combination of loads (fig. 4 (b)).
The initial defects of the rod piece are initial bending of the steel component caused by the machining precision during machining and initial stress of the component in the welding and splicing process. The steel structural design criteria (GB 50017-2017) gives two ways to take into account the initial drawbacks of the component: as shown in fig. 5 to 7, the initial bending of the member (formula 5.2.2-1 and fig. 6 (a)) is directly considered, and a virtual uniform load (formula 5.2.2-2 and fig. 6 (b)) is added to the member. Wherein: h-layer height; h-horizontal force; hn 1-fictitious horizontal force; e0—initial deformation value at the midpoint of the component. Wherein: δ0—initial deformation value (mm) at the end x of the element; e0—initial deformation value (mm) at the midpoint of the component; x—distance from end of member (mm); l-total length of the component (mm); q 0-equivalent distributed load (N/mm); nk—the standard value of the axial force (N) to which the component is subjected.
In summary, the existing method for adding the initial defects of the component is difficult and the existing technology has defects, and therefore, we propose a method for applying the initial defects of the rod in the joint analysis method.
Disclosure of Invention
The invention aims to overcome the defects of difficult addition and the defects of the prior component in the prior art, provides a method for applying the initial defects of a rod piece in a direct analysis method based on an API interface provided by design software, and solves the problems in the prior art.
In order to achieve the above purpose, the present invention adopts the following technical scheme: a method of applying an initial defect to a rod in a direct analysis method, comprising the steps of:
judging the rod type after obtaining rod units in a model, wherein the model is a three-dimensional entity finite element model established in finite element software SAP 2000;
based on the rod type, performing angle adjustment on the rod unit with the local shaft rotation;
setting a defect direction and an offset vector of the rod unit based on the rod type;
the rod units are given initial defects based on the rod type, defect direction and offset vector.
Preferably, the method is implemented based on an API interface provided by SAP2000 software.
Preferably, the bar types include vertical members and non-vertical bars.
Preferably, the angular adjustment of the rod unit with partial shaft rotation comprises in particular: the coordinate axis direction of the rod piece unit with the local axis rotation is subjected to angle adjustment through the conversion of a Rodrig rotation formula, wherein the Rodrig rotation formula is as follows:
V rot ＝cosθv+(1-cosθ)(v·k)k+sinθk×v
wherein: v is a three-dimensional space vector, k is a unit vector of the rotation axis, and Vrot is a vector obtained by rotating v by an angle θ about the rotation axis k in the right-hand screw rule sense.
Preferably, the defect direction is fixedly set.
Preferably, the offset vector is determined based on the increment of each direction of the rod unit in the overall coordinate system, and the increment of each direction of the rod unit in the overall coordinate system is obtained according to the offset length of the rod unit in the local coordinate system.
Preferably, the initial defect imparts a sinusoidal pattern to the rod units.
Compared with the prior art, the invention has the beneficial effects that:
the method for applying the initial defects of the rod piece in the direct analysis method can be used for conveniently and rapidly applying the initial defects to the rod piece, and is simple to operate and good in interactivity.
Drawings
FIG. 1 is a flow chart of a method for applying initial defects to a rod in accordance with an embodiment of the present invention;
FIG. 2 is a schematic diagram of setting an offset vector according to an embodiment of the present invention;
FIG. 3 is one of the schematic diagrams of the computational model of the framework structure;
FIG. 4 is a schematic diagram of the initial geometrical defect representation and the equivalent horizontal force of the whole frame structure;
FIG. 5 is a second schematic diagram of a computational model of a framework structure;
FIG. 6 is a graph of equivalent geometric defects and imaginary uniform loads;
fig. 7 is a schematic diagram of a calculation formula.
Detailed Description
The following drawings, which are included to provide a further understanding of the invention, illustrate and explain the principles of the invention, and together with the description serve to explain the principles of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without making any inventive effort are within the scope of the present invention.
Direct analysis software application feature comparison
The addition of the initial defects of the whole structure is the optimal choice by using buckling modes, and a plurality of software such as SAP2000, MIDAS, NIDA and the like support buckling analysis and also support the automatic addition of buckling displacement into the structure. The addition of the initial defects of the whole structure is very convenient, and the direction problem is not needed to be considered. In contrast, the addition of initial defects in components is difficult in SAP2000 and MIDAS, and NIDA provides PEP units that can directly take into account the initial defects in components, which is very convenient to operate. Fig. 1 is a schematic flow chart of the implementation of the technical scheme of the embodiment, and a method for applying initial defects of a rod in a direct analysis method includes the following steps:
judging the type of the rod piece, acquiring a rod piece unit in the model, distinguishing a vertical member from a non-vertical rod piece, defining a default direction of the rod piece, considering two directions of X, Y axes of a transverse section for initial defects of the rod piece, and firstly acquiring a X, Y axis direction angle of the rod piece to realize the middle node offset of the rod piece, wherein 1 axis in SAP2000 corresponds to an axial direction, 2 axis corresponds to a Y axis of the transverse section, 3 axis corresponds to an X axis, and 1,2 and 3 axes simultaneously meet a right-hand spiral rule. The default direction of the bars is related to the type of bars, and for vertical members such as column members, the default bar 2 axis is parallel to the global coordinate system X axis; for non-vertical bars, the default bar 2 axis is in the vertical plane.
For the definition of the shaft 2,3 axes in SAP2000, the local axis rotation angle also needs to be considered for the angular adjustment of the shaft with the local axis rotation. The angle can be obtained by the GetLocalAxes () method in the SAP2000 API, and the angle value obtained is the angle by which the 2,3 axis rotates about the positive local 1 axis. If the rod piece has partial shaft rotation, the directions of the 2 and 3 shafts need to be adjusted in angle, and the angle adjustment is obtained through the conversion of the Rodrign rotation formula. Rotdrign rotation formula (1): let v be a three-dimensional space vector and k be a unit vector of the rotation axis, v is a vector Vrot obtained by rotating the rotation axis k by an angle θ in the right-hand screw rule sense.
V rot ＝cosθv+(1-cosθ)(v·k)k+sinθk×v (1)
Setting a defect direction, wherein the defect direction considers the defect direction of a fixed rod piece so as to be convenient for engineering application; for non-vertical rods, the included angle between the defect direction and the gravity direction is smaller than 90 degrees, namely the deflection of the rod piece under the action of gravity is simulated. At this time, the Z-direction components of the 2 and 3 axes need to be determined, and if the Z-direction component is greater than 0, the reverse operation needs to be performed.
The offset vector is set and the offset operation provided in the SAP2000 API is to offset the current global coordinate system for the unit, so that it is necessary to find the increment in each direction in the global coordinate system based on the offset length of the bar in its local coordinate system. The offset length of the middle point of the rod is 1/400-1/250 of the length of the rod, and the new space positioning at the middle point can be determined by obtaining the vectors e of the 2-axis offset and the 3-axis offset and the length offset. Referring to fig. 2, an included angle between the offset vector e and the XY plane is set to be α, and an included angle between the projection of the offset vector e on the XY plane and the positive X axis is set to be β. The increment in each direction can be represented by α, β and offset length offset, see equation (2):
for each included angle α, β in equation (2), it can be expressed according to the offset vector e, see equation (3):
the initial defects of the rod are applied, the initial defects of the rod can be distributed by adopting a sine function according to the steel structural design standard (GB 50017-2017), and the maximum defect value e of the midpoint of the component in the embodiment of the invention 0 The rod piece can be divided into four equal-length sections according to the classification of the components, the offset distance of the middle dividing point is set as offset for the three dividing points, the limit value range is 1/400-1/250 of the length of the rod piece, and the offset distance of the dividing points at the two sides isoffset。
When the rod member is a vertical column, the 2 and 3 axis directions of the section of the rod member are specially defined, after the column member is divided and shifted towards the defect direction, the SAP2000 sets the divided rod member as a non-column member, and the 2 and 3 axis directions of the rod member are defined according to the mode of the non-column member and are different from the actual required condition.
Therefore, when the rod member is a vertical column member, after the division point is shifted, the advanced shaft attribute of the local shaft of the newly generated rod member after division needs to be set, so that the 2 and 3 shaft directions of the newly generated rod member are kept consistent with the original vertical column member, and the method can be realized by a SetLocalAxesAdvanced () method in the SAP2000 API.
Claims (2)
1. A method for applying an initial defect to a rod in a direct analysis method, comprising the steps of: the method comprises the following steps:
judging the rod type after obtaining rod units in a model, wherein the model is a three-dimensional entity finite element model established in finite element software SAP 2000;
setting a defect direction and an offset vector of the rod unit based on the rod type;
assigning an initial defect to the rod unit based on the rod type, the defect direction, and the offset vector; the method is realized based on an API interface provided by SAP2000 software;
the rod types include vertical members and non-vertical rods;
the angular adjustment of the rod unit with the local shaft rotation specifically comprises: the method comprises the steps of carrying out angle adjustment on the coordinate axis direction of a rod piece unit with local axis rotation through the transformation of a Rodrig rotation formula, wherein the Rodrig rotation formula is as follows:
V rot ＝cosθv+(1-cosθ)(v·k)k+sinθk×v
wherein: v is a three-dimensional space vector, k is a unit vector of a rotation axis, and Vrot is a vector obtained by rotating an angle theta around the rotation axis k under the right-hand spiral rule meaning of v;
the defect direction is fixedly arranged;
the offset vector is determined based on the increment of each direction of the rod unit in the integral coordinate system, and the increment of each direction of the rod unit in the integral coordinate system is obtained according to the offset length of the rod unit in the local coordinate system;
the initial defects are endowed to the rod piece units in a sinusoidal mode;
for a vertical rod, the defect direction is default set to the positive 2-axis and 3-axis directions of the component; for a non-vertical rod, the included angle between the defect direction and the gravity direction is smaller than 90 degrees, namely the deflection of the rod piece under the action of gravity is simulated, at the moment, the Z-direction components of the 2 and 3 axes are required to be judged, and if the Z-direction component is larger than 0, the reverse operation is required to be carried out;
setting an offset vector, the offset operation provided in the SAP2000 API is to offset the current overall coordinate system of the unit, so that the increment of each direction in the overall coordinate system is needed to be obtained according to the offset length of the rod piece in the local coordinate system, the value range of the offset length of the middle point of the rod piece is 1/400-1/250 of the length of the rod piece, the new space positioning at the middle point can be determined by obtaining the vector e and the length offset of the 2-axis offset and the 3-axis offset,
setting the included angle between the offset vector e and the XY plane as alpha, the included angle between the projection of the offset vector e on the XY plane and the positive X axis as beta, and the increment of each direction can be represented by alpha, beta and offset length offset, as shown in the formula (2):
for each included angle α, β in equation (2), it can be expressed according to the offset vector e, see equation (3):
maximum defect value e of component midpoint 0 The rod piece can be divided into four equal-length sections according to the classification of the components, the offset distance of the middle dividing point is set as offset for the three dividing points, the limit value range is 1/400-1/250 of the length of the rod piece, and the offset distance of the dividing points at the two sides is
2. The method of applying initial defects to a rod in a direct assay according to claim 1, wherein: based on the rod type, the rod units with partial shaft rotation are angularly adjusted.
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| CN202110751937.2A CN113505508B (en) | 2021-07-02 | 2021-07-02 | Method for applying initial defects of rod piece in direct analysis method |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4472681A (en) * | 1980-03-06 | 1984-09-18 | Republic Steel Corporation | Workpiece defect severity classifier with timing circuit to divide workpiece into equal inspection quadrants |
| US4629985A (en) * | 1984-04-11 | 1986-12-16 | Pa Incorporated | Method and apparatus for measuring defects in tubular members |
| CN102277899A (en) * | 2011-04-29 | 2011-12-14 | 深圳市建筑设计研究总院有限公司 | Method for determining calculated length of rod piece with large-span spatial structure and complicated boundary conditions and application thereof |
| CN102433879A (en) * | 2011-11-17 | 2012-05-02 | 武汉大学 | Assembly for applying prestress to glass fiber reinforced plastic anchor rod and using method thereof |
| WO2013046037A1 (en) * | 2011-09-30 | 2013-04-04 | Akitebolaget Skf | Moulding apparatus for receiving and holding a mould assembly |
| CN106092728A (en) * | 2016-07-19 | 2016-11-09 | 河海大学 | The control method of each point three-dimensional stress in asphalt circle ring column test specimen |
-
2021
- 2021-07-02 CN CN202110751937.2A patent/CN113505508B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4472681A (en) * | 1980-03-06 | 1984-09-18 | Republic Steel Corporation | Workpiece defect severity classifier with timing circuit to divide workpiece into equal inspection quadrants |
| US4629985A (en) * | 1984-04-11 | 1986-12-16 | Pa Incorporated | Method and apparatus for measuring defects in tubular members |
| CN102277899A (en) * | 2011-04-29 | 2011-12-14 | 深圳市建筑设计研究总院有限公司 | Method for determining calculated length of rod piece with large-span spatial structure and complicated boundary conditions and application thereof |
| WO2013046037A1 (en) * | 2011-09-30 | 2013-04-04 | Akitebolaget Skf | Moulding apparatus for receiving and holding a mould assembly |
| CN102433879A (en) * | 2011-11-17 | 2012-05-02 | 武汉大学 | Assembly for applying prestress to glass fiber reinforced plastic anchor rod and using method thereof |
| CN106092728A (en) * | 2016-07-19 | 2016-11-09 | 河海大学 | The control method of each point three-dimensional stress in asphalt circle ring column test specimen |
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