آشنایی با نرم افزار Multiframe وبلاگ مهندسی دریا kmsu.mihanblog.com

2. Contact Information
• Philip Christensen
• Formation Design Systems
• philc@formsys.com
• www.formsys.com
• www.formsys.com/academic
• Password frog5cove

3. Tutorial Program
1. Introduction to Multiframe
2. Structural modeling & intro to Section Maker
3. Loads and load cases – sample problem
4. Understanding results – sample problem
5. Assignment
6. Assignment

4. Background to Multiframe
• What is Multiframe?
• Structural analysis and design software
• Linear 3D beam elements
• “Stick and Ball” model of primary structure
• Good for framed structures, less suited to
slab and wall structures

5. Using Multiframe
• Setup
– Units
– Size
• Basic Concepts
– Global axes
– Local axes
– Section Axes
• Frame, Load, Plot windows

6. Steps in structural analysis
1. Geometry
2. Connectivity
3. Materials/Section Properties
Frame Window
4. Member Types
5. Restraints
6. Loads Load Window
7. Analysis
Plot Window
8. Results

7. Geometry
• Joint coordinates
• Member lengths
• Sketch in Frame window
• Modify by double click
• Modify in Data window

8. Connectivity
• Defines which members are
connected to which other
members
• Done automatically as you draw
in Frame window
• Can be reviewed in Member table
in Data window

9. Materials/Section properties
• Define size and materials of
structural members
• Sections are stored in Library
• Custom sections are possible
• Section Maker helps with
section property calcs
• Applied to members in the
Frame window

10. Member Types & Orientation
• Section Orientation
• Also known as “beta” angle
• Member releases define pins
at ends of members
• Applied to members in the
Frame window

11. Restraints
• Define how structure is “held down”
• Commonly pinned or rigid
• Apply to joints in Frame window
• Custom restraints are possible

12. Loads
• Automatic self weight
• Loads on joints
– Point loads or moments
• Loads on members
– Point or Distributed
• Consider a number of loading conditions or
cases
• Factored combinations of load cases

13. Analysis
• Static linear (1st order)
1st Order
• Static nonlinear
– (2nd order, large deflection)
Load
– P. ∆ and P. δ 2nd Order
• Dynamic modal
• Dynamic time history
Deflection

14. Results
• Deflections
• Actions
– Forces, moments
• Stresses
– Axial, bending, shear
• Diagrams in Plot window
• Tables in Results window
• NB Deflection diagram is exaggerated

15. Sample Problem
• 2D Truss to carry 1 x 20kN load at middle of a 10m span
• Goals are –
– Deflection not greater than 40mm
– Axial stress not greater than 100MPa
• How light can you make it?
– Use Data Window/Sections table to check weight
20kN
10m

16. Section Maker
• Utility for calculating properties of a
structural shape
• Weight, Area, Ix, Iy, J, E, G are required for
Multiframe
• Others are useful for stresses and design

17. Using Section Maker
• Placing Sections
• Placing Shapes
• Drawing Shapes
• Importing Shapes
• Properties
• Limitations
– No overlapping shapes
– J approximate in some cases

18. Structural Modeling
1. Use clipping and masking to manage
more complex models
2. Importing DXF
3. Modeling trusses
4. Modeling frames
5. Common errors

19. Data Import - DXF
• DXF - AutoCAD, Microstation etc
• Import 3D DXF from any CAD system
• Each LINE/POLYLINE segment
becomes a member in Multiframe
• No arcs in polylines
• Don’t use local extrusion axes
• Make sure any BLOCKs are exploded
prior to export
• Check units in DXF file are consistent
with Multiframe
• Use rotate command after import if
necessary

20. Modeling Trusses
• Trusses resist loads using axial
actions only
– bending
• Structure must be completely
triangulated
– Be careful in 3D
• Set joint types to pinned
• Usual to apply only joint loads
• Review deflections and axial
forces in results
– Tension and compression

21. Modeling Frames
• Frames resist loads using combination of
bending and axial forces
• Columns carry vertical loads as axial forces and
resist horizontal loads by bending
• Beams resist vertical loads by bending
• Braces resist transverse loads by axial tension
or compression

22. Common modelling errors
• Setting all joints to be restrained
– Only the joints at the
foundations should be restrained
• Drawing a member through a
joint
– Every member must run from
joint to joint. Subdivide if
necessary.Check by selecting
the member.
• Duplicating members so they
touch but are not connected to
other members
– Check using animation
• Getting loading units wrong

23. Load Cases
• Common load cases
– Self weight (Permanent) • Multiframe commands
– Dead load (Permanent) – Add Self Weight
– Live load (Imposed) – Add Static Load Case
– Wind load – Add Combined Load Case
– Load combinations
• Load magnitudes are determined using
AS1170 or from first principles

24. Dead Load
• Loads which are permanently applied to the
1 Pa = 1 N/m2
structure
•
1 N = 1 kg x g
For joint loads, consider area which will
contribute load to that joint g = 9.8 (~10)
• For member loads, consider area which will
load that member
• For trusses its common to apply joint loads
P B
w
L
P (N) = B (m) x L (m) x w (Pa)

25. Live Load
• Loads which are temporarily applied to the
1 Pa = 1 N/m2
structure
•
1 N = 1 kg x g
e.g. Pedestrians on the walkway
• w determined from no. of pedestrians per sq g = 9.8 (~10)
metre and average weight per person
P B
w
L
P (N) = B (m) x L (m) x w (Pa)

26. Wind Load
• AS1170 prescribes wind load calculations
• q = 0.5 * ρ * V2 * Cf
– q is design wind pressure Pa
– ρ is air density = 1.2 kg/m3
D
– V is wind speed in m/s (assume 40 m/s)
– Cf is a shape factor (default to 1.0)
• Total load on member = L * D * q L
• Load per unit length w = q * D
– D = depth of member perpendicular to air flow
• Direction of load is parallel to air flow

27. Loading Areas
• Tributary area
– Use to transfer pressure to a
member supporting an area
– Be careful with units
– More complicated patterns with
4-way supported slabs
W=P.d kN/m
where P is in kPa and d is in metres

28. Sample Problem Tree top walk

29. Tree top walk

30. Tree top walk

31. Tree top walk

32. Plan
Worked Example
• Tree Top Walk Truss, Walpole WA
• Length 60m, max depth 4m, max
width 3.0m, width at ends 1.0m
• Bottom chord 50mm rod, top
chords CHS168x4.8, transverse
members RHS150x50x4, bracing
CHS102x4
• www.donaldsonandwarn.com.au
Side Elevation

33. Worked Example Loads
• Consider self weight, dead weight, live load
and wind.
• Dead weight comes from 100mm thick jarrah
walkway
• Dead weight also comes from side railings at
70kg/m
• Live load comes from human traffic
• Wind load as per AS1170
• Self+Dead+Live+Wind
• Assume load is only applied at nodes of truss

34. Worked Example Dead Loads
• Self Weight using Add Self Weight load case
• Jarrah decking, 6m segment x 0.5m wide x
0.1m thick= 0.6m3
• Density of Jarrah is 800kg/m3 = 480kg = 4.8kN
• 6m handrail @ 70kg/m = 420kg = 4.2kN
• Total 9kN per node. 9kN
9kN
6m

35. Worked Example Live Loads
• People standing on deck
• 6m segment x 0.5m wide= 3m2
• Average person 70kg, one per square metre
• 3 x 70 = 210kg = 2.1kN per node
2.1kN
2.1kN
6m

36. Worked Example Wind Loads
• q = 0.5 * ρ * V2 * Cf
– =0.5 x 1.2 * 40 x 40 = 960 Pa (~1kPa)
• Total load on member = L * D * q
• Load per unit on eg top chord
• w = q * D = 1 * 0.16 = 0.16 kN/m
• Repeat for each member of different depth
• Direction is perpendicular to length of truss

37. Analysis
• Static linear (1st order)
1st Order
• Static nonlinear
– (2nd order, large deflection)
Load
– P. ∆ and P. δ 2nd Order
• Dynamic modal
• Dynamic time history
Deflection

38. Results
• Deflections, forces, moments, stresses
• Diagrams in Plot window
• Tables in Results window
• Deflection diagram is exaggerated

39. Deflection Plots
• Exaggerated display of deflected shape
• Can exaggerate more or less using Scale
item in Plot dialog in Display menu
• Can set to true scale of displacement
using scale of -1
• Can overlay an action or stress as a color
on the diagram
• Can render the deflected shape
• Can animate the deflection shape and
save as an avi movie

40. Assignment
• Write the report as a self-contained
document
– Note any required external documents
• Use simple, annotated drawings to clarify
• Explain all assumptions
• Display intermediate as well as final working
of calculations and show all units
• Make sure units are consistent
• Use clear, simple, concise, professional
language

41. Student Models 1

42. Student Models 2

43. Student Models 3

44. Student Models 4

45. Student Models 5

46. Student Models 6

47. Student Work 1

48. Student Work 2

49. Student Work 3

50. Student Work 4

51. Student Work 5

52. Student Work 6

53. • © Formation Design Systems Pty Ltd
• PO Box 1293 Fremantle WA 6959
• Tel +61 8 9335 1522 Fax +61 8 9335 1526
• Email: philc@formsys.com
• Web Site: www.formsys.com