1. 1 Performance-Based Seismic Assessment of Skewed Bridges PEER by Ertugrul Taciroglu, UCLA Farzin Zareian, UCI PEER Transportation Systems Research Program

2. 2 Collaborators Majid Sarraf, PARSONS Anoosh Shamsabadi, Caltrans Students Peyman Khalili Tehrani, UCLA Peyman Kaviani, UCI Ali Nojoumi, UCLA Pere Pla-Junca, UCI

3. 3 Outline 1. Skew bridges & project goals 2.Modeling skew abutment response 3.Developing NLTH simulation models for skew bridges 4.Exploring and quantifying skew-bridge response 5.Discussion

4. 4 General Problem Performance assessment of skewed abutment bridges Appropriate modeling of bridge superstructure. Appropriate modeling of bridge abutment. Selection of appropriate input ground motions.

5. 5 Previous Studies Straight Abutment: Aviram, Mackie, and Stojadinovic 2008 Johnson et al. (2009), Kotsoglou and Pantazopoulou (2010), Mackie and Stojadinovic (2007), Paraskeva et al. (2006) Skewed Abutment: Abdel-Mohti and Pekcan (2008) Meng and Lui (2000), Maragakis (1984), Wakefield et al. (1991), Ghobarah and Tso (1974)

6. 6 Ground Motions Pulse-Like Fault-Normal Fault-Parallel Soil-Site Rock-Site  Three sets of GMs were selected by the PEER Transportation Research Program  40 GMs per set  Three types of GMs: Pulse-like, soil-site, and rock-site  Fault Normal: longitudinal direction; Fault parallel: transverse direction  The GMs are from mid- to large-magnitude  Near-source GMs  Selected GMs have a variety of spectral shapes, durations, and directivity periods 4.0 2.0 0.0 1.0 2.0 3.0 4.0 2.0 0.0 1.0 2.0 3.0 4.0 2.0 0.0 1.0 2.0 3.0 4.0 2.0 0.0 1.0 2.0 3.0 4.0 2.0 0.0 1.0 2.0 3.0 4.0 2.0 0.0 1.0 2.0 3.0

7. 7 Anatomy of an Abutment Seat-type There are also “monolithic abutments” plan view

8. 8 Skew Bridge Challenges Deck rotation (esp. for single span bridges) Backfill response (near field) Shear key failure Unseating High seismic demands on columns

9. 9 Skew Bridge Challenges Deck rotation (esp. for single span bridges) Backfill response (near field) Shear key failure Unseating High seismic demands on columns

10. 10 Skew Bridge Challenges Deck rotation (esp. for single span bridges) Backfill response (near field) Shear key failure Unseating High seismic demands on columns

11. 11 Skew Bridge Challenges Deck rotation (esp. for single span bridges) Backfill response (near field) Shear key failure Unseating High seismic demands on columns

12. 12 Skew Bridge Challenges Deck rotation (esp. for single span bridges) Backfill response (near field) Shear key failure Unseating High seismic demands on columns

13. 13 Skew Bridge Challenges Deck rotation (esp. for single span bridges) Backfill response (near field) Shear key failure Unseating High seismic demands on columns

14. 14 Skew-angled Abutments Skew happens ??

15. 15 Input parameters for “Hardening Soil” PLAXIS model L nom Abutment Modeling

16. 16 Abutment Modeling L skew ≠ L nom

17. 17 straight abutment with wall-width w r skew abutment with wall-width w r skew abutment with deck-width w r Abutment Modeling

18. 18 Bridge Modeling The Jack Tone Road On-Ramp Overcrossing The La Veta Avenue Overcrossing The Jack Tone Road Overhead

19. 19 Bridge Matrix

20. 20 Abutment Modeling Simplified Model Dual-Rigid Model Friction Model Skewed Model

21. 21 Abutment Modeling

22. 22 V N,C = 2360 kips V N,B = 1810 kips V N,A = 755 kips Bridge “C” Bridge “B” Bridge “A” Shear Key Modeling

23. 23 Deck Rotation – Bridge A Bridge “A”, Lower, Symt.: Old Models

24. 24 Column Drift Ratio – Bridge A Bridge “A”, Lower, Sym. Old Models

25. 25 Column Drift Ratio – Bridge B Bridge “B”, Lower, Sym. Old Models

26. 26 Deck Rotation – Bridge A Median Response, Bridge “A”, Lower, Symt.

27. 27 Deck Rotation – Bridge A Median Response, Bridge “A”, Lower, Symt. NO SHEAR KEY MODELED

28. 28 Column Drift Ratio – Bridge A Median Response, Bridge “A”, Lower, Symt.

29. 29 Column Drift Ratio – Bridge A Median Response, Bridge “A”, Lower, Symt. NO SHEAR KEY MODELED

30. 30 Deck Rotation – Bridge A Pulse 1, Bridge “A”, Lower, Symt.

31. 31 Column Drift Ratio – Bridge A Pulse 1, Bridge “A”, Lower, Symt.

32. 32 Probability of Collapse – Bridge A Skew Angle = 0 o Skew Angle = 30 o Skew Angle = 60 o 15% 10% 15% 10% 15% 10% Bridge “A”, Lower, Symt.

33. 33 Deck Rotation – Bridge B Median Response, Bridge “B”, Lower, Symt.

34. 34 Column Drift Ratio – Bridge B Median Response, Bridge “B”, Lower, Symt.

35. 35 Bridge “B”, Lower, Symt., Probability of Collapse – Bridge B Skew Angle = 0 o Skew Angle = 30 o Skew Angle = 60 o 38% 25% 38% 25% 38% 25%

36. 36 Shear Key Performance – Bridge A Abutment Skew Angle 150 120 90 60 30 0 Intercept Angle Number of Failed Shear Keys out of 40

37. 37 Shear Key Performance – Bridge B 150 120 90 60 30 0 Intercept Angle Abutment Skew Angle Number of Failed Shear Keys out of 40

38. 1.Develop a three-DOF macro-element through numerical simulations with 3D continuum FE models and analytical considerations for torsionally flexible bridges. 2.Finalize the bridge models including the new abutment model. 3.Rotate Ground motions? 4.Quantify the Sensitivity of Skew Bridge Response and Damage Metrics to Key Input Parameters 5.Update Caltrans Seismic Design Criteria for Skew-Angled Bridges Next Steps – August Meeting

39. Next Steps – This Meeting 1.Develop a three-DOF macro-element through numerical simulations with 3D continuum FE models and analytical considerations for torsionally flexible bridges. 2.Finalize the bridge models including the new abutment model. 3.Rotate Ground motions? 4.Quantify the Sensitivity of Skew Bridge Response and Damage Metrics to Key Input Parameters 5.Update Caltrans Seismic Design Criteria for Skew-Angled Bridges