STAAD.Pro Tips and Tricks Carlos Aguera
24th May 2011
Agenda • The following are the topics to be covered in this workshop of STAAD.Pro Tips and Tricks • 1) Macros and OpenSTAAD
• 2) Stage Construction • 3) Foundations • 4) Buckling Analysis • 5) Angle Profiles
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1) Macro using OpenSTAAD and VBA • Objective – To create a macro to review the results of a model and display the maximum displacement from a user selection of nodes.
• Create a VBA project • Create and use an OpenSTAAD Object • Test STAAD.Pro is open and a model loaded.
• Get analysis results from STAAD.Pro • Display a dialog with results in STAAD.Pro
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OpenSTAAD • What is OpenSTAAD?
• ASCII – Input data (*.STD) – Output data (*.ANL)
• Binary – Results (*.BMD, REA, DSP…..)
• Inside STAAD.Pro in a macro • External using ANY suitable environment (but STAAD.Pro must be running locally in the background) |5
STAAD.Pro Macro GUI • To Create:– Menu, Edit>Create New VB Macro – Menu, Edit>Edit Existing VB Macro
• To Use:– Menu, Tools>Configure User Tools – Toolbar
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Start a new Project • Open the STAAD example file, EXAMP08.STD • Start a new VB Macro project from the menu Edit>Create New VB Macro… • Navigate to ‘My Documents’, enter the file name:‘BE Together 2011.VBS’ and click ‘New’
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Create the macro • 'Create an instance of OpenSTAAD Object. – – – – – –
Sub Main () Dim oStd As Object Set oStd = GetObject(,"StaadPro.OpenSTAAD") ….. Set oStd = Nothing Exit Sub
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Check your work, Test 1 • Add a break point by clicking on in the grey column to the right of the line:Set oStd = Nothing • Run the macro by clicking on the green arrow
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Check that a file is loaded • Add the following after the line that creates the OpenSTAAD object:– Dim stdFile As String – oStd.GetSTAADFile(stdFile,"TRUE") – If stdFile = "" Then – MsgBox "This macro can only be run with a valid STAAD file loaded.", vbOkOnly – Set oStd = Nothing – Exit Sub – End If •
oStd.GetSTAADFile(stdFile,"TRUE") is the first use of the OpenSTAAD object created in the previous step.
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Check your work, Test 2 • Add a break point by clicking on in the grey column to the right of the line:oStd.GetSTAADFile(stdFile, "TRUE") • Run the macro by clicking on the green arrow • Click on the ‘Step Over’ icon on the toolbar and hover over the text stdFile. This should display the file name and path of the currently open STAAD file.
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Getting Load Case data • Add the following after the ‘End If’ test to see if a file is loaded:– – – –
Dim i as Integer Dim LCases As Integer Dim lstLoadNums() As Long Dim lstLoads() As String
– – – – – – –
LCases = oStd.Load.GetPrimaryLoadCaseCount() ReDim lstLoadNums(LCases) ReDim lstLoads(LCases) oStd.Load.GetPrimaryLoadCaseNumbers lstLoadNums For i =0 To LCases-1 lstLoads(i)= CStr(lstLoadNums(i)) &" : " & oStd.Load.GetLoadCaseTitle(lstLoadNums(i)) Next i
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Create a dialog to select a load case • Add the following after the units:– Dim nResult As Integer – Dim LCName As String – Dim LoadCase As Long
• Then with the cursor located after these click on the ‘Edit User Dialog’ icon on the toolbar to add a dialog
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Adding controls • Add ‘OK’ and ‘Cancel’ buttons
• Add a text string, Double click on it and change the caption to ‘Load Case’ • Click on the ‘>>’ button and change the caption of the dialog box to ‘Select Load Case’ • Click on the List box icon and add it onto the dialog box, resize it so that it better fits the space. • Click on the ‘Save and Exit’ Icon.
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Display the load case names • Note how the new commands have been added
• To display the load change:– ListBox 40,49,320,70,ListArray(),.ListBox1
• To – ListBox 40,49,320,70,lstLoads(),.ListBox1
• Save and Run the macro:-
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Handle a Cancel request • To find out if a button was pressed change the line:– Dialog dlg
• To – nResult = Dialog (dlg)
• Add the following immediately after:– If nResult <> -1 Then – Set oStd = Nothing – Exit Sub – End If
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Get the requested load case • If the cancel was not pressed, then the selected item in the list should be converted to the load case using the following:– LoadCase = lstLoadNums(dlg.ListBox1) – LCName =lstLoads(dlg.ListBox1)
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Get Selected Nodes – Dim NumSelectedNodes As Long – Dim SelNodeArray() As Long – NumSelectedNodes = oStd.Geometry.GetNoOfSelectedNodes ( )
– If NumSelectedNodes >0 Then – ReDim SelNodeArray(NumSelectedNodes) – oStd.Geometry.GetSelectedNodes ( SelNodeArray, 1) – Else – MsgBox “Please Select Nodes”, vbOkOnly – Endif
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Get the results • Define the following variables after the check to make sure that there are indeed some nodes selected:– – – – –
Dim j as Integer Dim NodeNo As Long Dim DisplArray(6) As Double Dim MaxDisplArray(6) As Double Dim NodeArray(6) As String
• Then….
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Get the results • Add the following to get the displacement data:– For i=0 To NumSelectedNodes-1 – NodeNo = SelNodeArray(i) – oStd.Output.GetNodeDisplacements (NodeNo, LoadCase, DisplArray()) – For j= 0 To 5 – If Abs(DisplArray(j)) > Abs(MaxDisplArray(j)) Then – MaxDisplArray(j)= DisplArray(j) – NodeArray(j)="N" & CStr(NodeNo) – End If – Next j – Next i | 20
Dealing with units • Add the following after the loop to build the name array – Dim unit As Integer – Dim DispLabel As String – – – – – – – – –
unit=oStd.GetBaseUnit Select Case unit Case 1 DispLabel="in" Case 2 DispLabel="met" Case Else DispLabel="???" End Select | 21
Display the result • Create a new dialog box, dlg2, called Max Deflection
• Add an OK button and 14 text strings:– – – –
Text, "Load case:" Text, LCName Text,"X:“, Text,"Y:“, Text,"Z:" Text, CStr(MaxDisplArray(0)), Text, CStr(MaxDisplArray(1)), Text, CStr(MaxDisplArray(2)) – Text, X DispLabel, Text, Y DispLabel, Text, Z DispLabel – Text, NodeArray(0), Text, NodeArray(1), Text, NodeArray(2)
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Display the result • The dialog should be arranged thus:-
• Save and test the macro | 23
Adding a Macro to your toolbar • Click on the menu item Tools>Configure User Tools. – Click on the icon ‘New’, and add the text ‘Max Deflection to the name. – Click on the ‘…’ button to the right of the Command string and navigate to the ‘My Documents’ folder and select the ‘BE Together’ macro
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Sample
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2) Stage Construction • Objective – To create a model where the results of loading in 2 construction stages are combined
• Consider the model EXAMP08 constructed in 2 stages:-
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Stages Stage 1 - Initial
Stage 2 - Final
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Philosophy • When considering stage construction, it is very important that the matrix for the initial model includes every DOF that will be active at some point. • Each model/construction stage should be completed with an analysis and CHANGE command. • Inactive members do not reduce the matrix size, but may leave nodes disconnected and warnings reported. • Supports and releases can be changed for each stage • With multiple models SET NL needs to be defined.
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Example • Objective – To analyse a model built in 2 stages and combining the forces from both stages.
• Open file ‘Examp08mod.STD’ • Open the model in the Editor • Run the analysis
• Review Output file – Note warning messages
• View results in the Post-Processing Mode | 30
Notes • Load cases are unique in all models/stages, e.g. if load case 1 for say dead loads exists in the initial model, then it should not appear again in one of the other stages. An alternative load case number should be selected
• The GUI will display members which are INACTIVE as they may be active in some load cases, but not others.
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Notes • If a self weight command is used in the different stages and the results combined, then this will include self weight on members in each of the stages. Consider the use of assigning self weight to only members added during that stage. • The Member Query dialog does not display bending moments on members that are inactive in one or more load cases!
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3) Foundation • Objective – To understand the methods available of accounting for a pad foundation as supports for a STAAD.Pro model
• Supports – Point • • • •
Traditional Spring Multi-linear spring Foundation
– Surface • Elastic Mat • Plate Mat
• STAAD.Foundation | 34
Analytical Supports • Basic – Fixed, Pinned
• Spring – Fixed But – Multi-linear spring
• Sub-grade modulus – Foundation Support
• Lift Off Supports – Compression Only Springs
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Example 1 – Support on compressible soil • Objective:– Model a Pin support on compressible soil
• Open file ‘Foundation 1.STD’ go to page General>Support
• Click on Create and on the ‘Fixed But’ sheet and enter:– KFY 100 kip/in – Release directions MX, MY, MZ
• Assign to the base of all the columns • Run the analysis
• Vertical displacement N2, -18.875 inch | 36
Example 2 – Pin support on banded soil • Objective:– 3 bands of soil below foundation, • 10 inches of 100 kips/in • 10 inches of 200 kips/in • 10 inches of 500 kips/in
• Open file ‘Foundation2.STD’ and go to page ‘General>Support
• Create and assign this multi-linear definition to all supports • Run the analysis • Vertical displacement N2, -14.675 inch | 37
Example 3 – Sub Grade support • Objective – 2ft x 3ft pads under columns with soil subgrade of 100 kip/ft2/ft
• Open file ‘Foundation 3.STD’ go to page General>Support • Create and assign the Foundation support defined as above • Run the analysis • Vertical Displacement N2, -7.493 inch
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Enforced Supports • Prescribed Displacements – Used as a in load cases where there is a given displacement
• Mass Modelling, – Missing Mass
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Example 4 – Enforced Displacement • Objective – Prescribe a 0.5 inch Z displacement in load case #2 at Node 13
• Open file ‘Foundation 4.STD’ • Define an ENFORCED BUT FX FY – Assign to node 13
• Define a 0.5 inch Support Displacement Load in load case #2 and assign to node 13 • Run the analysis | 40
Surface Supports • Elastic Mat – Assign to a selection of nodes – Issues with ‘inclusive’ angles
• Plate Mat – Assign to a selection of plates
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Example 5 – Slab on Grade • Objective
• Open file ‘Foundation5.STD’ • Create and assign a PLATE MAT in Y with a sub grade of 100 kip/ft2/ft (initially non directional) – Assign to all plates
• View the loading then run the analysis
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Example 5 – Slab on Grade (continued) • Change support to ‘Compression Only’
• Re run the analysis – Note iterative solution
• Upward displacement
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Foundation Design • STAAD.Foundation – Standalone or Integrated
• Plant Mode – 2 specialist tools
• Toolkit Mode – 6 specialist tools:-
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Example 6 – Foundation Design • Open ‘Foundation 6.STD’
• Run the analysis and go to the Foundation Design Mode • Set – All Supports – Include all load cases
• Launch STAAD.Foundation
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Example 6 – Foundation Design (continued) • General Info
• Main>Create a New Job – – – –
All Isolated US English
• Design – View the calculation sheets – View the GA Drawing
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4) Buckling Analysis • Objective – To understand the methods and principals of the buckling analysis in STAAD.Pro
• Standard Engine – Load Factor
• Advanced Engine – Buckling Modes
• Geometric Non-Linear Analysis – Can identify buckling by monitoring deformations due to incremental addition of loading | 48
Standard Solver • Iterative elastic
• Initial analysis establishes basic stiffness matrix, forces/deflections • Both the large delta effects and the small delta effects are calculated. These terms are the terms of the Kg matrix which are multiplied by the estimated BF (buckling factor) and then added to the global stiffness matrix K.
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Advanced Solver • First, the primary deflections are calculated by linear static analysis based on the provided external loading. • Primary deflections are used to calculate member axial forces. These forces are used to calculate geometric stiffness terms. Both the large delta effects and the small delta effects for members are calculated. These terms are the terms of the Kg matrix. • An eigenvalue problem is formed. | [ K ] - BFi*[ Kg ] | = 0 • STAAD.Pro reports up to 4 buckling factors (BF) and associated buckling mode shapes calculated. | 50
Geometric Non-Linear Analysis • The geometric non-linearity can be accounted for in the analysis by updating the global stiffness matrix and the global geometric stiffness matrix [K+Kg] on every step based on the deformed position.
• The deformations significantly alter the location or distribution of loads, such that equilibrium equations must be written with respect to the deformed geometry, which is not known in advance.
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Buckling Analysis • For an ideal column, the critical axial load is defined as:-
Pcr
2 EI 2
L
• B = D = 1m, L = 10m • E = 2.17*10^7 kN/m^3
• I = (B*D^3)/12 = 0.083 m^4 • Thus Pcr = 177780 kN | 52
Example 1 – Standard Solver • Objective – Confirmation of Euler Buckling load on a simple column.
• Check that ‘Advanced Analysis Engine is NOT set.
• Open file ‘Column.STD’ • Run the analysis and view the output file:-
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Example 2 – Advanced Solver • Close the model and activate the ‘Advanced Analysis Engine’ license • Re-open the file and run the analysis
• View the output file:-
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Example 3 – Buckling Arch • Objective – To view buckling shapes of a pinned arch
• Simple arch
• Pinned support • Lateral restraint at crown • Point load applied at crown
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Example 3 – Buckling Arch (continued) • Close any open model and check that the Advanced Analysis Engine License is set. • Open file ‘Arch Buckling.STD’
• Run the analysis • Go to the Post-Processing Mode>Buckling Page. – May be necessary to reset the Mode Shape scale using Structure Diagrams>Scales
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Example 3 - Buckling Analysis - Modes • Buckling Factors – – – –
7.002 16.302 24.925 (*) 40.018
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Example 3 - Buckling Analysis - Modes • Buckling Factors – – – –
7.002 16.302 24.925 (*) 40.018
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Example 3 - Buckling Analysis - Modes • Buckling Factors – – – –
7.002 16.302 24.925 (*) 40.018
(*) In-plane mode
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Example 3 - Buckling Analysis - Modes • Buckling Factors – – – –
7.002 16.302 24.925 (*) 40.018
Buckling Load = 24.925 * 0.1kN = 2.49kN
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Alternative Solutions • Define model as PLANE – Arch Buckling planeframe.STD
• Restrain nodes in Z direction – Arch Buckling restrained.STD
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5) Angles • Objective – To understand the correct use of analysis and design of angle profiles in STAAD.Pro to AISC 360-05
• Geometric and Principal Angles • Standard and User Profiles • Design issues
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Member Local Co-ordinate Systems • Technical Reference ‘1.5.2 - Local coordinate system’ – A local coordinate system is associated with each member. Each axis of the local orthogonal coordinate system is also based on the right hand rule. Fig. 1.5 shows a beam member with start joint 'i' and end joint 'j'. The positive direction of the local x-axis is determined by joining 'i' to 'j' and projecting it in the same direction. The right hand rule may be applied to obtain the positive directions of the local y and z axes. The local y and z-axes coincide with the axes of the two principal moments of inertia. Note that the local coordinate system is always rectangular.
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Axes • Principal -----------• Geometric --------------------
• Member Loads and Forces
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ST and RA Specifications
• ST specification, Z-Z axis is weak axis bending • RA specification, Z-Z axis is strong axis bending | 66
Rotation and Alignment • BETA command – 5.26.2 Specifying Constants for Members and Elements
• Alpha • ANGLE • RANGLE
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User profiles • Menu:– Tools>Create User Table – Type:- Angle
• Define key dimensions – R, minor axis radius of gyration
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Example • Objective – To see effect of point load on end of cantilevers formed from angle sections
• Open file ‘Angle.STD’ • Assign a 1 kip point load to the free ends of all the cantilevers • Run the analysis and view the end displacements
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Example (continued) • Member 1, bending about weak principal axis (ST) – Large vertical end displacement only
• Member 2, bending about strong principal axis (RA) – Small vertical end displacement only
• Member 3, bending about geometric axis – Resolve into principal axes
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Design Issues • Typically angles are used as axial only members, i.e. TRUSS
• AISC 360-05 – Section E – Design of Members for Compression, • E5 Single angle compression members (p35)
– Section F - Design of Members for Flexure, • F10 Single Angles (p58)
– Section G – Design of Members for Shear, • G4 Single Angles (p68)
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Design of Members for Compression • Compressive strength defined by equations in clause E3 (E7 if slender). • Choice of equation E3-2 or E3-3 defined by slenderness, KL/r • For Angles, effective slenderness ratios dependent upon L/rx where – rx = radius of gyration about geometric axis parallel to connected leg – Un-equal angles STAAD.Pro assumes longer leg (in future will add LEG parameter) – Equal angles rx is the same for both legs
• Reported in output as ‘CL.E’ | 72
Design of Members or Flexure • User specified AXIS – 1 – Principal (default) – 2 – Geometric (only permitted if with continuous lateral-torsional restraint)
• Lateral-Torsional Buckling F10, part 2 – Calculated using Me, the elastic-torsional buckling moment – Effective length
• Leg Local Buckling F10, part 3 – Is considered and reported if governing
• Reported in output as:– CL.F-Major and – CL.F-Minor
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Design of Members for Shear • Clause G4 – The nominal shear strength, Vn, of a single angle leg shall be determined using Equation G2-1
• AXIS 1 – Principal – Longer leg is used in calculation of Major Shear, – Shorter leg is used in calculation of Minor shear – Forces are as reported by the analysis engine
• AXIS 2 – Geometric – Forces are resolved and used in legs as defined above
• Reported in output as:– CL.G-Major and – CL.G-Minor
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Example 2 – Angle Design • Objective – To see effects of AXIS on an angle design
• Open file ‘Angle 2.STD’
• Run the analysis and view the results • Edit the input file and remove comments from the start of the 2 TRACK commands. • Re-run the analysis and view the results
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Summary • 1) Macros and OpenSTAAD – Creating a macro using VBA
• 2) Stage Construction – Using the INACTIVE command
• 3) Foundations – Analysis and Design
• 4) Buckling Analysis – Standard and Advanced solver methods and results
• 5) Angle Profiles – Analysis and design | 76
STAAD.Pro Tips and Tricks Carlos Aguera
24th May 2011
