1. Actions and Retrofit of Post Earthquake-Damaged Bridges
Riyad S. Aboutaha, PhD, F-ACI
Associate Professor
Syracuse University
Albany, NY
Sept. **, 2010
NYSDOT Syracuse University University at Buffalo

2. GENERAL OUTLINE Introduction and Classification of Post-EQ Repair
Post-EQ Retrofit of Bridge Elements
Field Guide for Post-EQ Retrofit of Bridge Elements
Summary and Conclusions

3. INTRODUCTION and CLASSIFICATION
OBJECTIVE
Provide field inspectors and engineers with a quick guide for post-earthquake retrofit of bridges
CLASSIFICATIONS
Immediate Action / Retrofit
Short-Term Retrofit
Long-Term Retrofit

4. INTRODUCTION and CLASSIFICATION
IMMEDIATE ACTION/RETROFIT
Intended to stabilize the bridge and reduce the likelihood of further damage or progressive collapse, particularly during after-shocks
Make the site safer for safer for further detailed inspection and retrofit

5. INTRODUCTION and CLASSIFICATION
SHORT-TERM RETROFIT
Intended to make the bridge safer for light emergency traffic (police cars, and ambulances, etc.), heavy emergency traffic (fire trucks) at limited speed, or allow ALL traffic.
Immediate and short term retrofits may overlap, where the immediate-retrofit may serve as short-term retrofit.

6. INTRODUCTION and CLASSIFICATION
LONG-TERM RETROFIT
Intended to restore the bridge to its original strength, and possibly strengthen the bridge to improve its seismic resistance
It may involve detailed seismic analysis of the bridge, as well as detailed design of the retrofit system by a structural engineer

7. INTRODUCTION and CLASSIFICATION
Deck Failure

8. INTRODUCTION and CLASSIFICATION
Superstructure Joint
Failure

9. INTRODUCTION and CLASSIFICATION
Pounding Damage

10. INTRODUCTION and CLASSIFICATION
Column Damage
(Flexure / Shear)

11. INTRODUCTION and CLASSIFICATION
Column Failure

12. INTRODUCTION and CLASSIFICATION

13. INTRODUCTION and CLASSIFICATION
BASIC ASSESSMENT
Identify the purpose of the element /sub-element
SHEAR FAILURE
Purpose of stirrups
Resist shear
Confine column
Prevent buckling of longitudinal bars

14. POST-EQ RETROFIT OF BRIDGES
MATERIALS
Steel: structural shapes, prestressing strands/bars, plates, and cables.
Fiber Reinforced Polymer (FRP) Composite
Polymer concrete
Polymer modified concrete / Non-shrink Grout
Special tools: flat jacks, chains, etc.

15. POST-EQ RETROFIT OF BRIDGES
Application of External Prestressing strands/bars
External Post-tensioning

16. POST-EQ RETROFIT OF BRIDGES
Application of Structural shapes/cables

17. POST-EQ RETROFIT OF BRIDGES
Application of Structural Steel Plates
Uniform
Confining
Pressure
1.0 inch thick
non-shrink grout
Min. ½” thick
Steel jacket
Steel jacketed circular column
Uniform confining pressure produced by
circular steel jacket

18. POST-EQ RETROFIT OF BRIDGES
Application of Structural Steel Plates
4.0” long steel angle with hole
for assembly of steel shells
spaced 3 feet center-center
Steel bolt
Assembly detail of a circular steel jacket

19. POST-EQ RETROFIT OF BRIDGES
Application of Structural Steel Plates
Steel back plate for field welding.
It is welded to one steel shell in shop,
and field welded to the other shell.
Details of the circular steel jacket’s shells

20. POST-EQ RETROFIT OF BRIDGES
Application of Structural Steel Plates
Non-Uniform
Confining
Pressure
Shear retrofit of rectangular column section using rectangular steel jacket
Non-uniform confining pressure produced
by rectangular steel jacket

21. POST-EQ RETROFIT OF BRIDGES
Application of Structural Steel Plates
Lap splice retrofit of rectangular column section
using elliptical steel jacket

22. POST-EQ RETROFIT OF BRIDGES
Application of FRP Composites
FRP Diagonal anchor
(a) Straight FRP sheet along with diagonal FRP anchors.

23. POST-EQ RETROFIT OF BRIDGES
Application of FRP Composites
Uniaxial FRP
Composite strip/sheet
Uniaxial Diagonal
FRP anchor
(b) Isometric view of a strengthened beam with straight FRP system on the tension side,
along with diagonal FRP anchors.

24. POST-EQ RETROFIT OF BRIDGES
Application of FRP Composites
Uniform
Confining
Pressure
FRP repaired circular column section
Uniform confining pressure produced by
circular FRP jacket

25. POST-EQ RETROFIT OF BRIDGES
Approach Roadways
Bridge Decks
Bridge Abutments
Bridge Piers and Column
Bridge Girders
Foundation

26. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Approach Roadway
In general, the level of damage is classified based on amount of settlement
For minor settlement (d<2”), it is not a critical structural damage, however, it may pose serious driving hazard, that may affect traffic safety (use warning signs)
For major settlement (d>6”), must check abutment and its wing walls
Retrofit: refilled/repaved

27. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Approach Roadways

28. POST-EQ RETROFIT OF BRIDGES Retrofit of Damaged Bridge Decks
Minor
Moderate
Severe

29. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Bridge Decks

30. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Bridge Abutment EQ

31. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Bridge Abutment

32. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Bridge Pier Columns
Typical Seismic Deficiencies

33. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Bridge Pier Column (Shear Failure)
Minor
Severe

34. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Bridge Pier Column (Shear Failure)

35. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Bridge Pier Columns
Typical Seismic Deficiencies

36. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Bridge Pier Column (Flexural Failure)
Minor
Severe

37. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Bridge Pier Column (Flexural Failure)

38. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Prestressed Concrete Girders

39. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Steel Girders

40. POST-EQ RETROFIT OF BRIDGES
Foundation Failure
(a) Pile Overload
(e) Rebar Flexural Yielding
(b) Shear Failure
(c) Anchorage Failure
(d) Pile Pullout
(f) Pile Shear Failure

41. POST-EQ RETROFIT OF BRIDGES
Retrofit of Damaged Foundation
Check Deformations (rotation, level), and concrete distress
Requires extensive structural evaluation and retrofit measures

42. Strategies page 1

43. Strategies page 2

44. Summary & Conclusions
Good understanding of the behavior of bridge elements helps identify the load path, and consequently the best retrofit system to ensure the continuity of the load path
A retrofit system is intended to serve the role of the damaged element or sub-element
Pay attention to the overall stability of the bridge system
Last but not least: SAFETY COMES FIRST!

45. THANK YOU!