Training

1
Austroads Bridge Conference 2004Hobart May 2004
Bridge Deck Behaviour Revisited Doug
Jenkins Interactive Design Services
2
Overview

• Changes in computing technology
• Illustration dynamic analysis animation
• Features of alternative analysis methods
• Hamblys comments on FE analysis
• Summary of findings in paper
• Examples of advanced analysis techniques
• Conclusions
• Copy of presenation www.interactiveds.com.au

3
Changes in Computing Technology

• 1976
• Text based punched card input
• 200 nodes grillage
• Linear static analysis
• Printed text output

• 2004
• Interactive graphical input
• 100,000 nodes 3D brick elements
• Non-linear and dynamic analysis
• Interactive, animated graphical output

4
ftp//download.intel.com/research/silicon/moorespa
per.pdf
5
Speed of Computer Systems Prof. E.L.
Wilsonhttp//www.csiberkeley.com/support_technica
l_papers.html
6
(No Transcript)
7
Animation
8
Hambly comments

• Powerful and versatile analytical ... with a
  sufficiently large computer,
• Often requested by clients, or proposed to a
  client,
• Cumbersome to use and is usually expensive.
• Choice of element type can be extremely critical
• Full time occupation which cannot be carried out
  ... by the senior engineer responsible for the
  design.
• Unlikely to have time to understand or verify ...
  data.
• Difficult to place his confidence in the results

9
Features of Analyses
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Grillage 1a
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Grillage 1b
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Grillage 1c
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Grillage 2
14
Grillage 2 - detail
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Plate Slab with Downstand Beams
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Brick Elements
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Brick Elements - detail
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(No Transcript)
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(No Transcript)
20
(No Transcript)
21
Beam and Plate Analysis Deflected Shape
22
Beam and Plate Analysis Long. Stress
23
Brick Elements Long. Stress
24
Brick Elements Cutting Plane
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Brick Elements Cutting Plane, Selected Element
26
Link Slab
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(No Transcript)
28
Animation
29
Dynamic Analysis
30
Animation
31
Summary of findings in paperAdvantages

• Transverse distribution of live loads -
  significantly reduce maximum design stresses in
  longitudinal members.
• Distribution of wheel loads - more accurate
  estimate top slab bending moments, without the
  need for introducing separate local analyses.
• Analysis of secondary effects such as
  differential temperature and shrinkage
• Ends of skew decks and link slabs modelled more
  exactly, including three dimensional effects.

32
Summary of findings in paperNo Longer a Problem

• Finite element models may now be produced and
  analysed using standard computing equipment in a
  shorter time than a grillage analysis would have
  taken in the recent past.
• The accuracy of complex models may be checked
  against grillage analysis, or individual elements
  may be checked against simple analysis methods.
• Three dimensional contour plots of stresses or
  plots of the deformed shape of structures are
  easily produced, allowing engineers not directly
  involved in the analysis to review the results,
  and check the validity of the model.

33
Summary of findings in paperDisadvantages

• More difficult to extract member actions,
  particularly for large elements such as bridge
  beams.
• Design engineers must be trained in the use of
  complex software to use it efficiently.
• Verification process may be more difficult,
  particularly if detailed analysis has resulted in
  lower design actions than a simpler analysis.

34
Review Hambly comments

• Powerful and versatile analytical ... with a
  sufficiently large computer,
• Often requested by clients, or proposed to a
  client,
• Cumbersome to use and is usually expensive.
• Choice of element type can be extremely critical
• Full time occupation which cannot be carried out
  ... by the senior engineer responsible for the
  design.
• Unlikely to have time to understand or verify ...
  data.
• Difficult to place his confidence in the results

35
Recommendations

• Standard analysis procedure- Plate slab model
  with longitudinal beam members
• Use pre and post-processor software, specifically
  designed for bridge decks.
• Use brick models to further refine the design, or
  to investigate the behaviour of non-standard
  features.
• Consider the use of non-linear analysis and slab
  membrane action - potential for significant
  refinement of deck slab design.