Journal "Scientific Israel- Technological Advantages" “Scientific Herald” of Voronezh State University of Architecture and Civil Engineering, Vol.11, № 2, 2009 MODERN PROBLEMS OF THE COMPUTER-AIDED DESIGN OF BUILDING STUCTURES

1. Journal "Scientific Israel- Technological Advantages"
“Scientific Herald” of Voronezh State University of Architecture and Civil Engineering,
Vol.11, № 2, 2009
MODERN PROBLEMS OF THE COMPUTER-AIDED DESIGN
OF BUILDING STUCTURES
E. Voiczek1 , V. Babaev 1 , E. Melamed 1, D.Beilin2
CUBUS-Engineering Software Israel
eliezer@cubus.co.il
Polumate Lyd.-INRC, Migdal HaEmek, Israel
bdima@bezeqint.net
ABSTRACT
The paper presents the basic modules of the new computer complex of calculation and design of
building structures MIVNECAD integrated into AutoCAD media. MIVNECAD allows to define
the stress-strain state of a structure at static and dynamic loading and to realize a number of the
main designing functions
Keywords: Building structures, Software, AutoCAD, Finite Elements Method
INTRODUCTION
Design technology of building structure (BS) underwent dramatic transformation over the last 20
as a result of universal graphic facilities focused on personal computers. Specialized graphic programs
(AutoCAD, IntelliCAD, ADT, Revit) have quickly won a leading place in the design technology,
therefore software designers are forced to consider specificity of these graphic complexes for creation
of the competitive products. It should be noted that in the second half of last century the universal
calculation tool “Finite Element Method” (FEM) was created, thereby need to develop the special
methods and algorithms of the specific BS calculation is no longer required.
Thus, the basic accent of BS designing was displaced: from calculation of elements and nodes to
their graphic representation (structural drawings). This concept forms the basis of the new computer
design-calculation complex Mivne CAD .
MIVNECAD presents а system of calculation based on FEM and designing of BS in the AutoCAD
media. It allows to define the stress-strain state of structure at static and dynamic loading and to
realize the main design functions (Figure 1)
.
Figure 1. Home page of MIVNECAD
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2. Journal "Scientific Israel- Technological Advantages"
“Scientific Herald” of Voronezh State University of Architecture and Civil Engineering,
Vol.11, № 2, 2009
INFORMATION MEDIA “PROJECT”
The system of the functional software modules connected by the uniform information media
Project is put in the MIVNECAD basis. Project contains the full information on the structural
scheme and the calculation model, which forms, presents and stores in internal formats of the
MIVNECAD complex (block Data Base). Each new problem has the name.
It is significant that of the structural scheme and calculation model of BS are organized in the
AutoCAD media. Standard software tools of AutoCADа and specially developed procedure Drawing
Construction are used at formation of input data. As this takes place the special fail “DWG” is
created and exported to Data Base of MIVNECAD (Figure.2)
Figure 2. Example of the created .dwg. file for following export to Data Base
The thickness of walls, the sizes of columns, overall dimensions of floors is defined automatically
from the .dwg drawing. The section of beams, a thickness of floor plates and values of permanent and
temporary loads are presented in the corresponding places of the drawing.
The sizes of the coordinate grid FEM , numbers of nods , elements and their type are appointed
automatically with possibility of updating in accordance with requirements of a solved problem
(Figure 3).
A distinguished feature of the calculation model is appointment of Base Point on the plans of
each floor as these plans can be presented in various coordinates. Routine program MIVNECAD
automatically constructs a 3D view of a designed building (Figure 4). The 3D view is used for an
estimation of the image of each floor (Figure 5)
Functional modules
Functional modules of MIVNECAD realized in AutoCAD media are divided into four groups:
• Input modules : provide input of the source information in an interactive graphic mode and
the graphic analysis of the calculation results .
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3. Journal "Scientific Israel- Technological Advantages"
“Scientific Herald” of Voronezh State University of Architecture and Civil Engineering,
Vol.11, № 2, 2009
• Calculation modules: provide static and dynamic calculations, calculation of structural design
force combination. Worst load combination, main and equivalent stresses and reactions.
• Documentation modules: provide documentation of the calculation results.
• Projecting modules: provide selection a reinforcement and design of reinforcement concrete
structural elements
Figure 3. Chart of coordinate grid of FEM. Example
..The modular structure generates the MIVNECAD configuration which as much as possible
meets the requirements for each user
The user interface of interaction with system, the input data control and the analysis of results is
completely unified, that provides minimum time for mastering of the complex and logical sequence of
the operations performance.
The highly extensive system Styles (Figure.6) is developed for simplification of the source data
input.
The processor and library of the finite elements
The high-efficiency processor allows solving of the static and dynamic problems with the degrees
of freedom data bulk.
The algorithm "Skyscraper" [3] was taken as the mathematical based algorithm of solution of
FEM equation systems. It allows to solve the extending systems with consecutive connection of the
new blocks (in the given MIVNECAD complex we mean the consecutive connection of floors).The
monitoring system of the input data carries out check of the design scheme and fixes all found out
errors, for example: load assemblage from the top floors on bottom. At the correct calculation the
loading diagram is close to a triangle (Figure 7).
The library of finite elements contains a universal bar element with six degrees of freedom in each
node and a rectangular element of a plane shell with five degrees of freedom in each node. These
elements can be used together with the elastic foundation
Use of the developed system of absolutely rigid inserts and hinges [4] allows to approximate
boundary conditions of the roof slabs and floor slab panel with satisfactory accuracy.
Design for vertical loading includes define the force values quantity and diameter of a
reinforcement in all elements of a building: plates, beams, walls and columns (Figures 8,9)
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4. Journal "Scientific Israel- Technological Advantages"
“Scientific Herald” of Voronezh State University of Architecture and Civil Engineering,
Vol.11, № 2, 2009
Figure 4. 3D image of the designed multistory building
Design of building structures for seismic and wind loadings
Quality and reliability of the analysis results depend on the chosen dynamic model. The accepted
dynamic model provides:
• Distribution of rigidities in a building;
• Distribution of masses;
• Seismic action on a building
The model is constructed on the basis of a set of assumptions:
• Floor slab panel is represented as absolutely rigid body in the its plane and flexible out of the
plane for transfer of shear forces on vertical structural elements;
• Groups of structural elements (walls, columns etc.) are replaced with an equivalent bar
located in «the centre of masses»; rigidity indexes of the bar correspond to rigidity of the
replaced elements
• Use of “substructures”
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5. Journal "Scientific Israel- Technological Advantages"
“Scientific Herald” of Voronezh State University of Architecture and Civil Engineering,
Vol.11, № 2, 2009
Figure 5 3D image of the designed floor
Seismic activity on building included in the dynamic model is based on the following
assumptions and hypotheses:
• The approximate static method [5]
• The approached dynamic method [5]
The model allows to perform the analysis which most close depicts properties of the designed
building
Dynamic analysis of a building is based on the FEM (Figure 10)
According to this method, the distributed masses are replaced with the concentrated masses in
finite number of points. At each stage of software work the obtained of results is examined on
conformity with standards [5.-7]
Graphic preprocessor
As note above the primary goal of the software MIVNECAD is its full integration with the
popular graphic complex AutoCAD, for use in full its soft hardware
Complex MIVNECAD possesses wide scale of expedients for formation and updating of design
model geometry , such as :
• creation of the structural model based on prototypes of structure,
• copying of the model fragments,
• assemblage of analytic model from subsystems and groups,
• various functions of geometrical transformations
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6. Journal "Scientific Israel- Technological Advantages"
“Scientific Herald” of Voronezh State University of Architecture and Civil Engineering,
Vol.11, № 2, 2009
Figure 6 System Styles for the source data input
.
Figure 7. Vertical loads assemblage (example)
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7. Journal "Scientific Israel- Technological Advantages"
“Scientific Herald” of Voronezh State University of Architecture and Civil Engineering,
Vol.11, № 2, 2009
Figure 8 Image and graphs of the stress state of a floor slab
Figure 9 Scheme of reinforcement’s location
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8. Journal "Scientific Israel- Technological Advantages"
“Scientific Herald” of Voronezh State University of Architecture and Civil Engineering,
Vol.11, № 2, 2009
Figure 10 Analysis results and diagrams of normal forces, moments and shearing forces along height
of the building
.
All key parameters of the model, including geometrical characteristics of beam sections, static
and dynamic loads etc. are given by in a graphic dialogue mode .The interface of preprocessor is
approximated maximum to creation and updating technology of design model and features of the
information processing
The set of facilities for geometry modification of an analytical model includes various kinds of
the geometrical transformations, allowing to change scale of the model or the indicated fragment, to
carry out its turn round the specified axis, to obtain mirror image, to transfer a model’s part on the
specified distance etc. These functions give the chance to create the design model practically any
complexity
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9. Journal "Scientific Israel- Technological Advantages"
“Scientific Herald” of Voronezh State University of Architecture and Civil Engineering,
Vol.11, № 2, 2009
Graphic postprocessor
Use of AutoCAD’s recourses for large design models allows to simplify the analysis of results
In parallel with analytical results graphical tool of MIVNECAD allows to display epures (for bar
systems) or isofields (for floor plates and roof slabs) of forces, displacements and deflections.
Analytical block of a reinforcement selection in reinforced concrete structural elements makes
possible to obtain the reinforcement area in the prescribe direction, width of cracks opening, percent
of reinforcing etc. By this means the form of the results representation becomes usual for an engineer
and creates for him additional comfort.
Any graphic information can be printed
Documentation of analysis results
The module of documentation of the analysis results allows provides to generate input data and
results tables with in a text format, and to export them in MS Word or MS Excel. Formation of the
tables is carried out according with the types of load-bearing structures; the tables allow to add
comments and to include the graphic information.
Thus, the report document can be edited by AutoCAD’s aid , to get the convenient form for the
user (for example according to the standard accepted in his company) and export in MS Word or MS
Excel for non-standard processing of results with reference to specific conditions.
ACKNOWLEDGEMENT
The authors thank Prof. Sh, Frostig, Dr. A.Grossman, Eng. A.Naginsky, Sh. Wogman, E. Besnovaty,
L. Sandler, A.Plotkin for their helpful comments to improve the quality of the software
REFERENCES
1. STRAP engineering software for the structural, civil and bridge engineering- Israel, 2007.
2. LIRA-Windows , Software, NIIASS, Ukraine, Kiev,-1996
3. N.N. Shaposhnikov, V.B. Babaev, G.B. Poltorakj, E.G. Petrushev, SPRINT, Software
MIIT, Moscow, 1985
4. E.Melamed ,Computational modeling of interaction of reinforced concrete structural
elements, DVGUPS, Khabarovsk, 1966
5. Standard 413 Design provisions for earthquake rsistance of structures SI-413 Israel, 2004
6. Standard 414, Characteristic Loads in Buildings: Wind Load, IS 414, 1982
7. Standard 466, Concrete Code: General Principles IS 466, 1987,
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