SAP2000 Academic Training
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SAP2000 Academic Training
By Civilax.com 1999
ACCELERATED TRAINING
SAP 2000
1. INTRODUCTION At present, many programs based on finite element method for MEF automatically calculate various structures available. The engineer could thus ignore the principles of the MEF, it needs only to know how to use computer programs and know the regulations in force. Only, that user would be unable to realize the correction of the results given by the computer. It is therefore essential that every engineer knows the basics of MEF, and also understand the process of the solution phase. This skill can only be acquired by the analytical study of the concept of MEF and knowledge of technology related to the use of these computational tools. The training's goal is the presentation of the fundamentals of automatic calculation of a point of view mainly physical while considering the computer code in its operating efficiency, ie as a tool for the professional uses. The latter can then taking into account the above considerations, formulate the problem of computing structure and monitor results provided by the computer almost effortless. 2. BASIC CONCEPT OF FEM The finite element method is a generalization of the method to the case of deformation structure having planes or larger items. The method considers the solid liquid or gaseous medium, constituting the structure as an assemblage of discrete finite elements. These are interconnected by nodes on the boundaries of these elements. The actual structures are defined by an infinite number of nodes. The structure is thus divided, it can be analyzed in a manner similar to that used in the beam theory manner. For each type of elements, a function of deformation (depending on shape) of polynomial form that determines the relationship between the deformation and the nodal force may be derived based on the principle of minimum energy, this relationship is known as name of the stiffness matrix of the element. A linear algebraic equation system can be established by imposing the balance of each node, while considering as unknown deformations in the nival nodes. The solution is to determine these deformations in following strengths and stresses can be calculated using the stiffness matrices of each element.
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3. DESCRIPTION SAP 2000 SAP 2000 is a software for calculating and designing engineering structures especially adapted to buildings and civil engineering works. In the same environment it allows graphical entry of construction works at a cell library approach allows the behavior of this type of structure. It offers many possibilities for analysis of static and dynamic effects with complements the design and verification of reinforced concrete structures, structural steel. The chart postprocessor available greatly facilitates the interpretation and exploitation of results and formatting calculation notes and explanatory reporting.
Modeling
The software allows the modeling steps (definition of the geometry, boundary conditions, loads of structures, etc.) in a totally graphic, digital or combined, using the myriad tools available. Indeed, a structure can be composed into sub patterns (porches, trellises, slab, sailing) each set in its corresponding graph database, then assembled into final calculation scheme, while the compatibility of connections automatically. Furthermore, finite element, associated with a graphic pattern generation bases (base mesh gantry frame beam, slab, or sailing hull, etc.), settings are directly (Figure 1) .
Figure 1: Library structures SAP 2000.
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The digital pre-processor that automatically translates the captured data graphically, provides ongoing support for the extension or correction of records generated. This digital data is translated into a file with an extension. $ 2K or S2K.
Figure 2: Example of a digital file automatically translates the graphical input.
Analysis
The program offers the following opportunities for analysis: - Linear static analysis: - P-Delta analysis. - Nonlinear static analysis. - Dynamic analysis.
Post - processor
SAP 200 software significantly facilitates the interpretation of results, including the ability to visualize: the deformed system, diagrams of efforts and envelope curves, the stress fields, the natural modes of vibration, etc. ..
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4. MODELING TOOLS SAP 2000
Coordinate system
To define a structure and system of loading, two types of coordinates are used. The global coordinate system is an arbitrary system in space, it is used to define the coordinates of the nodes and to give direction loads. The local coordinate system is associated with each element and is used for specifying local loads and interpretation efforts and therefore results.
Figure 3: Local and Global Axes of SAP 2000.
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4.1 "FILE" MENU 4.1.1 MODEL "TEMPLATE" The library elements specially adapted to facilitate construction works of the designer to make the model more complex structures (flat or three-dimensional structures composed of bar elements, plates or shells) in an optimal way for a static calculation or dynamics. 4.1.1.1 ELEMENT "FRAME" - TYPE POST AND BEAM It is the one-dimensional element with six degrees of freedom at the nodes, 3 translations and 3 rotations to resume efforts and 3 times 3. The beams and gantries elements can be inserted from the library structures using SAP 2000 "MODEL FROM TEMPLATE" statement The models in the library SAP2000 on FRAME elements, post and beam type are as follows: -
Beam; Portal frame; Braced frame; Eccentric frame; Space frame; Perimeter frame.
Beam
Portal frame
Braced frame
Eccentric frame
Space frame
Perimeter frame
Figure 4: Elements Gallery FRAME.
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After choosing the model of the structure of the library, you must specify the following characteristics for structural dimensions. -
Number of spans ........................................................................................... Number of spans Span length ...................................................................................................... Length of span Number of stories .......................................................................................... Number of steps Number of bays ........................................................................................ Number of gantries Story height........................................................................................................... Story height Bay width ................................................................................................. Width of the portico Gap width ............................................................................. Distance between nodes bracing Number of bays along X (Y) ................................................ Number of gantries along X (Y) Bay width along X (Y) .................................................................. Wide porches along X (Y)
4.1.1.2 ELEMENT "FRAME" - TYPE LATTICE A lattice bar means the bar can not take and pass the axial forces. Note that by declaring the item as bar mesh saves computation time. The software library contains the following types of systems lattice: -
Sloped truss; Vertical truss; Space truss.
Sloped truss
Vertical truss
Space truss
Figure 5: Library lattice elements - TRUSS. The characteristics of the mesh model of the library are selected according to the geometry of the structure to be modeled. These are: - Number of bays ........................................................................................ Number of gantries - Height of truss ............................................................................................... Height of lattice - Truss bay length...................................................................................... Length gantry lattice - Number of stories ......................................................................................... number of levels - Story height............................................................................................................level height - Top width along X (Y) .........................................................................greater width in X (Y) - Bottom width along X (Y) ....................................................................... Less width in X (Y)
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4.1.1.3 ELEMENT "SHELLS" They are used for modeling sails, blocks, and shells. The library contains the following models: - Shear wall; - Cylinder; - Barrel; - Dome.
Shear wall
cylinder
barrel
dome
Figure 6: Elements Gallery SHELLS The dimensions and the number of elements must be specified according to the type of structure to be modeled. These data are entered into the menu of the selected model are the following: -
Number of spaces along X (Z) ................................................................................................ Space width along X (Z) .......................................................................................................... Number of circumferential spaces ........................................................................................... Number of height spaces ........................................................................................................ Cylinder height ........................................................................................................................ Radius ...................................................................................................................................... Number of spaces span ............................................................................................................ Span ........................................................................................................................................ Roll down angle ....................................................................................................................... Number of segments ................................................................................................................
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4.1.2 IMPORT AND EXPORT FILES The software allow us to use files on other structures developed software like STAAD-III and SAP90 in DXF format with an option to import files calculation. However, SAP in 2000 with an option to export files in DXF format. Thus, it creates a digital input S2K file format which can be used as a file of SAP 2000.
Fishier import SAP90 SAP2000.S2K SAP2000.JOB .DXF Export files SAP2000.S2K .DXF
Figure 7: "FILE" Menu 4.2 MENU "EDIT" The "EDIT" menu mainly contains instructions on changing the structural geometry of the structure modeled.
4.2.1 MOVE (Move) This command enable linear displacement 03 in directions X, Y and Z nodes, elements, of a structural part, etc., depending on the geometry of the structure studied.
Figure 8: Overview of the MOVE option.
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4.2.2 REPLICATE (generate) This instruction help facilitate the modeling of structures by automatic generation of the similar elements in the linear radial direction. And a generation to mirror relative to a plan exists. For linear generation must specify the number and distance units to three axes quadratic X, Y and Z. However, the angle and the axis of rotation and the number of elements to be generated, must be specified in the If a radial generation.
EXAMPLE
Gantry base
Figure 9: Example of linear and radial generation.
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4.2.3 Unwound FRAME (FRAME elements Subdivide) This instruction permit to subdivide a FRAME several identical or non-members. However, the FRAME element can be divided by the intersection with the grid selected automatically at the beginning or obtained by instruction GRID EDIT DRAW menu.
Figure 10: Example of subdivision of the FRAME element.
4.2.4 MESH SHELLS (Subdivide SHELLS items) Even preceding specifications, except that the plate member is subdivided in two directions thereof. In addition to the plate member has a two-way division by the intersection with the selected grid, can be subdivided into the mouse by selecting nodes where the element will be broken. A beam element takes into account exactly all load cases that are imposed and there is therefore no a priori accuracy problem. As against the size of plate elements directly affects the convergence of the solution. In general the smaller the size of the element is small and the more refined analysis results are accurate. However, the execution time (number of digital iterations) increases significantly with the degree of refining discretizations. In the same model can be used different sizes depending on the sensitivity of each region. Another feature relating to the dimensions of the element is the ratio of the largest dimension to the smallest dimension of the element. A ratio close to unity generally provides better results.
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Figure 11: Example of a refined mesh of plate members.
4.3 "DEFINE" MENU The instructions in this menu provides an easy tool to capture geometrical and mechanical definition of static and dynamic load characteristics. 4.3.1 MATERIALS (Material Properties) This instruction permit introduction mechanical and elastic properties of the material of the elements of the model structure. The software assigns default characteristics of the two materials, concrete and steel that can be changed according to your requirements. Types of materials can be customized by inserting the following properties in the book this option menu. -
Properties for calculation
Mass per unit volume .................................................................................................. Density Weight per unit volume ............................................................................................... Gravity Modulus of elasticity ................................................................................................. Modulus Poisson's ratio ....................................................................................................coeff. Poisson Coeff of thermal expansion ......................................................................... Thermal Gradient
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Properties for design of reinforced concrete
Reinforcing yield stress, fy ........................................ Elastic deformation of steel (400 MPa) Concrete strength, fc .................................... Characteristic strength of the concrete (25MPa) Shear steel yield stress, fs ........................................................ Design stress steels (348MPa) Concrete shear strength, fcs ..................................... Shear strength of the concrete (25 MPa)
Property for design of the steel structure
- Steel yield stress, fy ........................... Elastic deformation of the metal profiles (E24 or E36)
Reinforced concrete
Steelwork
Figure 12: Menus for specifying material properties.
Default properties SAP2000
E (Mpa) DENSITY (KN / m3) Coeff. Poisson Thermal Gradient
STEEL 2.0 108 76.80 0.3 1.17 10-5
CONCRETE 2.48 107 23.56 0.2 9.9 10-6
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4.3.2 FRAME SECTIONS (Section elements FRAME) The geometric characteristics of the elements must be specified for each group of elements of the same size. These properties can be introduced directly in terms of prismatic features: cross sectional area of the rod, moments of inertia with respect to local axes 2 and 3, constant torsion bar heights according to local axes 2 and 3 for taking into account deformations due to shear. However, these properties can also be specified in terms of the dimensions of the key section, and the program (software) automatically calculates the necessary properties for analysis of the structure and the structure of the verification. SAP 2000 also presents possibilities for defining the geometrical characteristics from databases (library metal sections) standard steel profiles or profiles with variable inertias. These types of profiles can be imported from the following files: Aisc.pro, Cisc.pro and Sections.pro. Different types of metal sections are: -
Wide Flange (1); Channel (2); T (3); Angle (4); Double Angle (5); Box / Tube (6); Pipe (7); Rectangular (8); Circle (9).
Figure 13: Overview of the geometrical characteristics of the elements FRAME.
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(1)
SAP 2000
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
Figure 14: Different sections of the database 200 of the SAP. 4.3.3 SHELLS SECTIONS (Section elements FRAME) SHELLS section elements is defined by the thickness. There are several types of plate elements which are: SHELL ELEMENT They are used for modeling sails, boards and hulls. This type of element that will balance the moments of axes tangent to the surface and perpendicular to the plane tangential forces. Three degrees of freedom are taken into account in each node, two rotations in the tangent plane, a translation perpendicular to the plane which are associated two times and strength.
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MEMBRANE ELEMENT
The membrane element is that the strength balance tangent to its surface, and therefore can not transmit bending moments. In practice, this type is used for thin items.
SHELL ELEMENT
This is the superposition of the plate element and membrane (assembly of the two schemes below).
Figure 15: Efforts of the resulting two-dimensional elements. 4.3.4 STATIC LOAD CASES (Definition of load cases) 15
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This allow to define multiple load cases and their types, such as, dead loads (DEAD), operations (LIVE), seismic (QUAKE), wind (WIND), snow (SNOW) are distinguished and option other. The own weight of the structure is taken into account by the coefficient 01 in the case of loads. This coefficient can be changed as appropriate. For example, the own weight is canceled in the case of which the operating load coefficient is replaced with 0.
Figure 16: Menu specification load cases. 4.3.5 RESPONSE SPECTRUM FUNCTIONS (Function response spectrum) The 2000 SAP software contains in its database response spectra defined by the American seismic code (Uniform Building Code) and are UBC94S1, UBC94S2 and UBC94S33. In Algeria the response spectrum is defined by the seismic code RPA99. The function of the design spectrum is given by the following system of equations:
T Q 1.25 1 2.5 1 R T1 Q 2.51.25A R SA 2/3 g 2.51.25A Q T2 R T 2/3 5/3 2.51.25A Q T2 3 R 3 T
0 T T1 T1 T T2 T2 T 3.0S 3.0S T
Along with: T1 & T2 = 0.15s = 0.4s.
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A: Acceleration Coefficient area. R: Coefficient of global behavior of the structure. Q: Quality factor.
Figure 17: Example of the response spectrum given by the RPA99.
Figure 18: Menu For data of the response spectrum
4.3.6 RESPONSE SPECTRUM CASES (spectral dynamic load) This load case can take into account the structure of the modal response as a response spectrum applied to the base. It is based on the modal superposition method which is described by the following steps: Formulation of coupled equations of motion by calculating the mass matrix, rigidity and damping.
MX CX K X p(t ). ..
.
Calculation of natural frequencies and modes.
M ²KA 0. Calculate the mass matrix and generalized loading.
mr r Mr T
pr r p t T
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Determination of the equations of motion decoupled.
pr mr Calculation of the modal response. y r 2 r r y r r2 y r
x Ni1 r y r
Figure 19: Menu concerns the spectral dynamic load 4.3.7 LOAD COMBINATIONS (Load Combinations) This statement is used to introduce load combinations by multiplying each load case by their coefficient of increase given by the regulations of calculation. These combinations can be specified for the calculation of design of reinforced concrete and structural steel according to American codes by enabling the option USE FOR CONCRETE (STEEL) DESIGN.
Figure 20: Menu concerning seizure load combinations.
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4.4 "ASSING" MENU The instructions in this menu are used to define the support conditions, the values of each load case, etc. 4.4.1 JOINTS (Nodes) 4.4.1.1 RESTRAINTS (Conditions restraints) The supports can be specified as articulated as built or as embedded with some relaxations. The articulated support is considered to be released in rotation and locked in translation. SAP2000 also lets you specify spring constants in translation or rotation, allowing the definition of elastic supports.
Recessed
Double support
Joint
Free node
Figure 21: Different types of media.
The user must specify the program in a number of modes of the node of the fixing structure with the outside environment (support), and between these elements. Generally the connection of two elements in a node may be a hinge, a locking recess or a few degrees of freedom. SAP in 2000, all nodes are recognizing rigid default nodes.
4.4.1.2 SPRINGS (Elastic supports)
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This option allows us modeling the elastic supports specifying the stiffness of the node 'K'. These nodes have been supported on springs stiffness 'K (KN / m)' in the direction of translation and rotation. For example, modeling the ground, neoprene, etc. Z (3) y (2) X (1)
Figure 22: Menu concerning seizure rigidities elastic supports. 4.4.1.3 MASSES (Ground) The masses used in the calculation of dynamic structure are calculated and distributed over the nodes. Essentially, the option is used to distribute the weight of the floors on the nodes.
Z (3) y (2) X (1)
Figure 23: Menu concerning seizure rigidities elastic supports. 4.4.2 FRAME 4.4.2.1 SECTIONS After defining all kinds of sections to be used in the structure, this instruction is to specify the type of section for each element of the structure. For example, the posts are FSEC1 type beams are FSEC2 type, etc.
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4.4.2.2 Prestress The bars may be of a structure subjected to a prestressing load, which can change the distribution of loads in the structure. The load of the prestress can be centered or eccentric to the axis of the bar means. The positions are specified for the cable ends of the bar and at mid-span. The effects of stress can be transmitted to adjacent rods (reactions) or assumed that the bias is already performed and therefore does not cause a reaction in the structure.
Figure 24: Menu concerns the input data preloading. 4.4.2.3 RELEASE (Release the ends of the elements) This statement frees some degree of freedom of the nodes to eliminate efforts in a given direction. For example, a lattice bar system only allows the normal force and the shearing force, thus the rotation is free to remove nodes times.
Figure 25: Menu concerns RELEASE statement.
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4.4.3 SHELLS (Elements plates) SECTIONS After defining all kinds of sections to be used in the structure (DEFINE menu), this instruction is to specify the type of section for each plate element of the structure. 4.4.4 JOINT STATIC LOADS (Forces or displacements applied to the nodes) The specification is to translate loads the nature of permanent loads, service or accidental in a set of forces, moments, acceleration or displacement applied to the nodes of the elements. The program includes tools for generating loads that define calculations without prior fillers such as different cases of linear and planar distributed loads, own weight, thermal loads, prestressing, and also equipped with generators of mobile charges, wind and seismic. The fillers can be two types: point loads or distributed loads. Nodal point loads or expenses are expenses that the user explicitly introduced on some nodes of the mesh, they can be applied as nodal forces, displacements or rotations nodes (Figure 26). Loads, forces or moments can be applied to any node of the structure. These loads are acting in the directions of the global coordinate system. Several charges can be applied to each node, in which case the charges are added at this point.
Figure 26: Example of loads at the nodes.
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4.4.5 STATIC LOADS FRAME (FRAME elements applied to the charges) The loads applied to the FRAME elements can be in many forms which may be mentioned: - Uniformly distributed loads. - Trapezoidal loads. - Point loads. - Temperature loads. The loads (forces or times) are oriented along the axes of the global structure. These are specified by their directions of loading, application points for point and trapezoidal loads and values. The program calculates the axial stress (lengthening or shortening) due to the temperature difference, by introducing the temperature difference (T max and T ° ° min).
Uniform
Concentrated
V
Figure 27: Examples of charges on FRAME elements.
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4.4.6 Shelle STATIC LOADS (surface charges) SAP in 2000 to specify the surface charges on the two-dimensional elements. The program provided for this load to be evenly distributed per square meter depending on local or global axes. The thermal load can be specified as a temperature gradient between the mounting conditions and the conditions of service, resulting in a lengthening or shortening of the bar.
Figure 28: Menu concerning the specification of surface charges. 4.4.7 JOINT PATTERNS (Distribution of charges whatsoever nodes) This allow automatic transmission of the resulting linear or surface option loads the nodes. These fillers are defined by the following equation: Ax + By + Cz + D
Figure 29: Menu concerns SEAL Pattens order.
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4.5 "ANALYZE" MENU
STATIC ANALYSIS LINEAR
A linear static analysis to determine the displacement field, recreation restraints, the internal forces at the nodes and the stress field existing in a structure subjected to various static loads several implicit assumptions are made: - Linear elastic behavior of materials. - Small deformations. - Small rotations. The linear static analysis is based on the displacement method of satisfying the balance of forces and accounts of trips each node in the model structure. To achieve the full analysis of the structure, the stiffness matrix is obtained by the superposition of contributions from different rigidities of the bars and of the elements constituting the structure. The compound of the force vector and external loads distributed to the nodes of the structure. The equation with several unknowns (displacement) thus obtained is solved using the method of Cholesky decomposition that is well suited for this type of problems.
ANALYSIS P-DELTA
Delta-P analysis, also known as a second order analysis, allows to take into account the effect of axial loads on the bending behavior of the elements. SAP 2000 uses a simple and efficient algorithm for calculation based on the reformation of the vector force versus deformation undergone by the structure while keeping the constant stiffness matrix. The calculation steps is summarized in the following: - Calculation of deflections in the case of initial load. - Calculation of secondary loads due to movements of the nodes associated with traditional efforts. These vectors nival charges are added to the vectors of the initial charges. - Calculation of deflections and deformations and effort with the same stiffness matrix as a result of the force vector corrected. This method is particularly useful for the consideration of the effects of gravity on the lateral stiffness of the structures, as required by certain codes.
NONLINEAR STATIC ANALYSIS
SAP 2000 also offers the possibility of a non-linear calculation taking into account the geometric nonlinéairité. The algorithm for this analysis is based on the geometric correction of the stiffness matrix and load vector simultaneously. This type of analysis is generally suitable for structures that deform appreciably under the effect of loads applied to them. The calculation steps are:
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The movements of the applied loads are calculated. Estimates based on the deformed geometry corrections are then made to the stiffness matrices of the elements and a new global matrix is rebuilt. Vectors charges are revised to include the side effects of these movements. The new system of equations is solved to give further displacement. The forces on the components and reactions of supports are then calculated from these new displacement. The algorithm is iterative, user can specify the number of iterations required knowing that the execution time increases with the number of iterations. DYNAMIC ANALYSIS
Dynamic analysis available in SAP 2000 includes modal analysis, spectral analysis and temporal analysis.
MODAL ANALYSIS
Modal analysis is used to determine the natural modes and frequencies of structures. Since there is no external force, the natural frequencies and natural modes are a direct function of the rigidity and the mass distribution of the structures. Therefore, the calculation result of the frequencies of the natural modes and can vary considerably depending on the modeling of the masses.
SPECTRAL ANALYSIS
The spectral analysis is used to calculate the seismic response of a structure using a response spectrum. The modal responses are combined using the method of the complete quadratic combination CQC (Complete Quadratic Combination) or SSRS. The results of spectral analysis can be combined with the static analysis results for the dimensioning of the structure. To account for the reversibility of the seismic loads, load combinations can be created by including the contributions of seismic design with the - / +.
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TEMPORAL DYNAMICS ANALYSIS
In cases where a deterministic analysis study temporal dynamics is required, SAP 2000 has the possibility of calculating the response of a structure under the effect of a dynamic load applied to any node or ground movement ( at the base). The calculation method is based on the modal superposition, which gives the response of the structure. The procedure is to first calculate the modes and frequencies of the system to calculate the matrix of generalized mass and generalized load vector, which will then be used for decoupling of the differential equations of motion. The modal response to imposed loading is calculated by the numerical integration method using the algorithm Wilson- with a constant time interval selected by the user in the order of 0.1T (T being the period of the highest mode to be included in the answer). Finally the answer is expressed in terms of geometric coordinates efforts in the elements and support reactions.
OPTIONS ANALYSIS DATA BY SAP IN 2000
Figure 30: Menu in which the specification of analysis options.
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For dynamic analysis, one must specify the number of modes used in the calculation in a way one must have a mass greater than 90% participation. Regarding the P-Delta analysis, we have to specify the number of iterations and tolerance made in the calculation of forces and displacements.
Figure 31: Menu For data to be specified for the P-Delta analysis and dynamic.
4.6 MENU "DISPLAY" The 2000 SAP greatly facilitates the interpretation of results, including the ability to display: 4.6.1 SHOW LOADS (Graphical visualization of forces) This instruction allows graphic visualization of the charges and values.
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4.6.2 SHOW TABLES INPUT (Digital Display of INPUT) The instruction INPUT SHOW TABLES allows digital display loads and geometric coordinates of the different elements of the structure.
Figure 32: Example ofINPUT TABLES. 4.6.3 Deformed SHOW SHAPE
(Viewing of the deformed system)
Deformations under any load case can be traced and values of deformations at nodes or spans can be viewed or printed.
Figure 33: Plots of the deformed.
4.6.4 FASHION SHOW SHAPE
(Playback modes of vibration)
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Deformed eigenmodes can be illustrated and animated for a better understanding and control modes of the structures in space. Many features and commands allow the scaling of the image, fragmentation, zoom, digital indexing, etc. As well as a video file (AVI) can be created that contains the animation of the mode shape.
Figure 34: Plot of the mode shape. 4.6.5 SHOW ELEMENT FORCES / STRESSES (Visualization of forces and constraints) The diagrams of shear forces, axial forces or bending moments can be traced for the entire structure or element. Fields constraints or contours can be flat or show for the volume elements.
Bending moment
Shear
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Figure 35: Diagrams solicitations.
Figure 36: Contours of the stresses and strains.
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METAL SHED WITH CRANE
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MODELING STEPS
A simple model from the software library (25m wide and 20m high) gantry.
Subdivided into two higher element using the unwound FRAME option.
Moving the intermediate node along the Z axis 2m by the MOVE command.
Subdivision poles identical elements 20 (each 1.m)
Subdivision sleepers three bays to create nodes for achieving the horizontal braces.
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Generation posts by 1.m distance (between column axis compound).
Modeling pole lattice compound (generating elements 17 along the Z axis from a base member designed by the mouse).
Generating similar porticos along the Y (10 gantries with a center distance of 6m) axis.
Adding elements to the axis Y //, tq, the bearing beams and braces and other items, is made on only one span. Next, the generation of these elements is set as appropriate. For this, enable the option SET LIMIT and select two gantry shore.
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Generation of new elements for other gantries specifying the number and no generation. (6m with no number 9)
Modeling vertical and horizontal braces by adding elements FRAME by mouse only for a span, then makes the generation of these. But first we must divide the two beams to connect the nodes bracing beams.
Definition of groups
IPE450-1 IPE450-2 IPE450-3 IPE450-4 TRAVERS TREILL IS CONT-H CONT-V HEA600 PTR-ROOF PTR
TRAVERS HEA600 IPE450-1 IPE450-2
IPE450-3 IPE450-4 LATTICE
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CONT-H
TRAVERS
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PTR-ROOF
PTR
Definition of different types of sections
The elements of the structure are steel frame whose sections of the profile is imported from a file (Euro.Pro) continent types of metal profiled. For this reason, the steps are: -
Menu selection 'DEFINE' Select submenu 'DEFINE FRAME SECTION' Click to 'I IMPORT / WIDE FLANGE' Selected file profiled 'Euro .Pro' Select the profiles IPE450, IPE400, HEA600, HEA200 (Posts, beams, beam rolling, cross). Click to 'IMPORT ANGLE' Select a cornier 15010010 (Lattice pole compound) Click to 'IMPORT CHANNEL' Chose a UPN260 (bracing)
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Definition of load cases
G, Q, V, N, Ex, Ey, T Where:
G: dead load. Q: operating expense. V: wind load. N: snow load. Ex, y: spectral seismic loads in the x, y. T: load due to temperature. These load cases are introduced by the command '' Static loads boxes'.
Defines the response spectrum calculation.
The response spectrum given by the RPA99 is introduced as acceleration depending on the period.
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Case definition spectral dynamic load.
-
specification of the damping factor (Donated by RPA99) Specifying the application of each response spectrum management.
-
SAP 2000
This load case is specified by the DEFINE DEFINE RESPONSE SPECTRA menu.
Definition of load combinations
Load combinations are defined from sub menu LOAD COMBINATION.
-
Specification supports Selecting only the nodes of support by 'SET LIMITS'. Type specification supports using the button
Specifying sections of each element.
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Item selection is made by selecting the groups, then the type specification section of the selected elements is set from the ASSIGN menu. For example: -
Select IPE450-1 groups IPE450-2, IPE450-3, IPE450-4. Specify these IPE450 the profile using the ASSIGN menu and sub menus FRAME-SECTIONS.
Same procedure for the other elements as before using the item selection by groups or by other selection options (SET LIMITS for example). Some elements of the structure does not have the bending moment. For example, the lattice pole compound and bracing. The release of those elements is in rotations made by RLEASES option after selecting those components.
Specifying the load
In the case of this example, the dead load, operating, snow are applied uniformly distributed over the cross. The steps are: -
-
Select sleepers (THROUGH group) Activate the submenu 'POINT AND UNIFORM SPAN LOADS' ASSIGN menu. Give values for each load (by specifying the load case and the loading direction)
The wind load is horizontally applied on poles compounds along the Y axis, following the same steps as above, as applied vertically on the sleepers. Values and direction of application are given by the Snow and Wind settlement.
Specification of masses for dynamic calculation.
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The dynamic calculation is done by the introduction of horizontal loads (in the X, Y) introduced by the MASSES in the ASSIGN menu menu - JOINTS. The introduction of these weights is necessary for calculating the spectral dynamic.
Setting the Analysis options
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BUILDING A 4 R + D'HOME AND OFFICE USE This structure is a steel frame building for offices and housing. It comprises gantries modeled by the method of generation, and composite floors, it is assumed embedded in the ground. The building is located in the seismic zone 2. DIMENSIONS IN THE STRUCTURE PLAN Length (X) ........................................................................................................................ 24.0 m Width (Y) ......................................................................................................................... 12.0 m Height (Z) ......................................................................................................................... 16.5 m
6m
6m
5m
5m
4m
5m
5m
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STAGES OF MODELING
Choosing a model of spatial structure from the library.
Using the MOVE command to change the length of intermediate span 4m to 5m.
Defining standard metal profiles to be used:
-1m
HEA340; HEB260; IPE360; IPE200. These sections are defined from Euro.Pro file by activating the option of DEFINE FRAME SECTION menu.
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Beams IPE200
Beams IPE360
HEB 260 posts
HEA 340 posts
HEB 260 posts
SAP 2000
Beams IPE200
Beams IPE200
Definition of load cases.
G; Q; Ex1; EY1; Ex2; EY2. Tq: G: dead load. Q: operating expense. Ex1 (y1) equivalent static load in X (Y) Ex2 (y2): spectral dynamic load in X (Y)
Defines the response spectrum given by the RPA99 using the RESPONSE SPECTRUM DEFINE FUNCTIONS menu.
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Case definition for dynamic load spectral Ex2, EY2.
The spectral dynamic load is applied in both X and Y directions separately, as it is unfair to apply the two functions of the response spectrum in a load case (X or Y) at the same time.
Definition of load combinations.
G+Q 1.35G + 1.5Q
G + Q + Ex1 G + Q-Ex1 G + Q + EY1 G + Q-EY1 G + Q + Ex2 G + Q-Ex2 G + Q + EY2 G + Q-EY2
G + Q + 1.2Ex1 G + Q-1.2Ex1 G + Q + 1.2Ey1 G + Q-1.2Ey1 G + Q + 1.2Ex2 G + Q-1.2Ex2 G + Q + 1.2Ey2 G + Q-1.2Ey2
0.8g + Ex1 0.8g-Ex1 0.8g + EY1 0.8g-EY1 0.8g + Ex2 0.8g-Ex2 0.8g + EY2 0.8g-EY2
Specification of support conditions.
The structure is assumed embedded at its base. The definition of the latter is established by the restraints control or the menu
Introduction of the masses of floors for spectral dynamic calculation in horizontal direction X, Y.
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In the case of this structure, they are calculated in this manner. W = Wp + Q Wp = own weight. = 0.2 Q = operating expense. Weight of the deck is not accessible: Wterr = 2003.5 + 0.2 288 = 2061.2KN Weight of the floors: Wétage = 1818.4 + 0.2 (660 + 96) = 1969.7KN Total weight of the structure: Wtotal = 2061.2 + 4 = 1969.7 9940KN
Each floor is 18 knots. Therefore, the above values will be divided on 18 and gave the following values: Wterr / node = 114.5KN Wétage / node = 109.5KN
Specifying different loads.
Dead load G: Floor deck G = 5 kN / m² Current G Floor = 4 KN / m² Charges farms Q: Floor deck Q = 1 KN / m² Q = current floor 2.5 KN / m² These charges are introduced by the FRAME command STATIC LOADS (uniformly distributed load) Ex1 equivalent static loads, y1:
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These forces are distributed to nodes floors. The calculation of the latter is determined using the method given by RPA99. ADQ W R
v
where: A = 0.15; D = 2.5; Q = 1.10; R = 5. V
0.15 2.5 1.1 9940 820KN 5
Load Distribution:
Fi
V Ft
Wi H i
n
W H j 1
j
j
f1 = 314.60KN f2 = 276.50KN f3 = 236.00KN f4 = 195.40KN f5 = 154.90KN f1 / node = 17.50KN f2 / node = 15.36KN f3 / node = 13.11KN f4 / node = 10.86KN f5 / node = 08.60KN
EVEN BUILDING R 4 WITH SOLID SLABS
Same steps as above except:
The floors are modeled by elements SHELLS. The loads are applied directly on the slab (surface charges) using the UNIFORM LOADS SHELL command ASSIGN menu after selecting items to load. For the dynamic study, the masses can be applied to the nodes of the posts, and they can be applied in each node of the slab (element nodes SHELLS), dividing the mass of the floor on them.
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MODELING A RAFT ON ELASTIC SUPPORTS
Consider that the foundation of the previous structure is a general ribbed slab. The floor is modeled as a solid slab, and the ribs are modeled as beams. Modeling riffles is based primarily on the assumption that the soil is an elastic support. In this case, all the nodes of the raft (INCL) to be considered elastic supports specifying the soil stiffness "K" by the ASSIGN SPRING option menu after selection of the nodes of the raft (usually k is between 40 and 80MPa / m3)
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