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

2. Overview: l Changes in computing technology l Illustration – dynamic analysis animation l Features of alternative analysis methods l Hambly’s comments on FE analysis l Summary of findings in paper l Examples of advanced analysis techniques l Conclusions l Copy of presenation: www.interactiveds.com.au

3. Changes in Computing Technology l 1976 l Text based punched card input l 200 nodes; grillage l Linear static analysis l Printed text output l 2004 l Interactive graphical input l 100,000 nodes; 3D brick elements l Non-linear and dynamic analysis l Interactive, animated graphical output

4. ftp://download.intel.com/research/silicon/moorespaper.pdf

5. Speed of Computer Systems Prof. E.L. Wilson http://www.csiberkeley.com/support_technical_papers.html

7. Animation

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

9. Features of Analyses

10. Grillage 1a

11. Grillage 1b

12. Grillage 1c

13. Grillage 2

14. Grillage 2 - detail

15. Plate Slab with Downstand Beams

16. Brick Elements

17. Brick Elements - detail

21. Beam and Plate Analysis – Deflected Shape

22. Beam and Plate Analysis – Long. Stress

23. Brick Elements – Long. Stress

24. Brick Elements – Cutting Plane

25. Brick Elements – Cutting Plane, Selected Element

26. Link Slab

28. Animation

29. Dynamic Analysis

30. Animation

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

32. Summary of findings in paper No Longer a Problem l 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. l 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 paper Disadvantages l More difficult to extract member actions, particularly for large elements such as bridge beams. l Design engineers must be trained in the use of complex software to use it efficiently. l Verification process may be more difficult, particularly if detailed analysis has resulted in lower design actions than a simpler analysis.

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

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