Visual Inspection and Condition Evaluation

1. Visual Inspection and Condition Evaluation (Bridge #1618-150 in Wayne, NJ) Jungseok Lee*, Namhee Jin, Jongchul Kim & Soobong Shin PEC, KCQRC & Inha Univ. Republic of Korea

2. Contents • Introduction of Bridge Inspection System of Korea • Summary of Visual Inspection Results • Summary of NDT Results • Result of Condition Evaluation • Intervention for Repair

3. Introduction • Special Law for the Safety Maintenance of Infrastructures • Established in 1995 just after the tragic collapse of Sungsu Bridge in Korea • Regulation for maintenance of important infrastructures • KISTEC(Korea Infrastructure Safety & Technology Corporation) was established by Government according to this law which is responsible for the safety maintenance of important infrastructures • All guidelines and manuals for inspection and condition evaluation have been made by KISTEC under the supervision of Korean Government

4. Introduction • Classification of Inspection • Initial Inspection • After construction, widening, strengthening, etc. • Routine Inspection • Every 6 months • Brief inspection for important and/or damaged members • Precision Inspection • Every 2 years • Detail inspection for all members & NDT • Condition evaluation • In-depth Inspection • Every 5 years • Precision inspection & structural safety assessment • Damage Inspection • Unscheduled inspection for the environmental attack or car accident

5. Introduction • Procedure of Condition Evaluation of a Bridge • 3-stage condition evaluation [element-level] → [span-level] → [bridge-level] Element-level CE span-level CE for girder span-level CE for Pavement support-level CE for Pier • • Avg. Element-level CE Element-level CE defect investigation Weighting on members Minimum level Bridge-level CE

6. Introduction • Condition Rating at Element Level • Classification and Grades for Elements • Primary structural members : a – e • Secondary or non-structural members : a – d

7. Introduction • Categories of CE at Element Level • Concrete Slabs • Steel members(slabs, girders, piers, pylons) • Reinforced concrete girders • Pre-stressed concrete girders • Concrete cross beams • Steel cross beams and stringers • Cables • Abutments • Concrete piers • Footing, piles, caissons • Bearings • Expansion joints • Pavement • Drainage • Railings and curbs • Carbonation • Chloride content * Total 17 categories (15 member groups and 2 concrete material tests)

8. Introduction • Criterion for Concrete Slabs • cw : crack width • cr : crack ratio = crack area / surface area (crack area = length x 0.25m) • Ac : damaged concrete area • Acs : damaged concrete area with reduction of sectional area of reinforcement by corrosion

9. Introduction • Criterion for Steel Members(Slabs, Girders, Piers, etc.) • Nbs: # of damaged bolts on secondary members • Nbm: # of damaged bolts on main members • Asp: Damaged painting area of steel members • Asc: Corroded area of steel members • Asl: Corroded area with sectional loss of steel members

10. Introduction • Criterion for Concrete Piers • cw : crack width • Ac : damaged concrete area • Acs : damaged concrete area with reduction of sectional area of reinforcement by corrosion

11. Introduction • Condition Rating at Bridge Level • A to E • Results from visual inspection and NDT

12. Introduction • Condition Rating at Bridge Level • Weighting Factors

13. Introduction • Condition Rating at Bridge Level • Result of Condition Evaluation • Damage Index (DI)

14. Summary of Visual Inspection • Concrete Slabs • Deck plates : good condition (no delamination, no leakage) • Concrete slabs : good condition with small lateral cracks (Deck plates) (Cracks in cantilever of slabs)

15. Summary of Visual Inspection • Steel Plate Girders • Inner girders : good condition (no corrosion) (Inner girders) (End of inner girder)

16. Summary of Visual Inspection • Steel Plate Girders • Outer girders : poor condition (severe corrosion with sectional loss on lower flanges) (Outer girders) (End of outer girder)

17. Summary of Visual Inspection • Steel Plate Girders • Fatigue cracks on webs were reported in DOT reports • but couldn’t indentify by visual inspection • induced by vibration of lateral bracing due to differential deflection of girders (Crack with stopholes) (Location of web cracks, drawing by UT) (Crack without stopholes)

18. Summary of Visual Inspection • Concrete Piers • Good condition • Shear cracks and spalling were developed on the vertical surface of P1 southbound caused by omitting vertical reinforcements in the pier cap on the top of column • Bending cracks were developed underside of pier cap of P2 (Shear crack of pier cap) (Bending crack of pier cap)

19. Summary of Visual Inspection • Abutment (A1) • Poor condition • Severe vertical cracks and fault were developed • Severe shear cracks were developed both side surface (Crack and fault of A1)

20. Summary of Visual Inspection • Abutment (A2) • Poor condition • Severe vertical cracks on the parapet and severe shear cracks were developed both side surface (Crack and fault of A2)

21. Summary of Visual Inspection • Bearings • Under inner girders : good condition • Under outer girders : poor condition (corrosion and sectional loss) (Inner bearing) (Outer bearing)

22. Summary of NDT • Concrete NDT • Compressive Strength • Rebound test using Schmidt Hammer (Column) (Pier Cap) (Abutment)

23. Summary of NDT • Compressive Strength • Design Strength : 21 Mpa • Compressive strength of piers and abutments is estimated to exceed the design strength

24. Summary of NDT • Arrangement of Re-bars • Using handy GPR(Ground Penetrating Radar) • Measuring rebar spacing and concrete cover depth (Abutmrnt) (Pier Cap)

25. Summary of NDT • Arrangement of Re-bars • Compared with design values • Good matching except slight difference in horizontal re-bars of abutment

26. Summary of NDT • Steel NDT • Sectional Loss of Steel Members • Thickness measurement using ultrasonic equipment • Sectional loss of outer steel girders by corrosion (Thickness measurement of lower flange of steel girders)

27. Summary of NDT • Sectional Loss of Steel Members • Lower flange of outer girder southbound • Original thickness : 25.4 mm • Measured thickness : 25.0 mm • Sectional loss rate : 1.6%

28. Result of Condition Evaluation

29. (Special Consideration on Cracks & Spalls in Pier Cap) • Vehicle Loading • AASHTO LRFD Code (HS 20-44 +10% load scale) • Multiple presence factor for 4 lanes (1.2 / 1 / 0.85 / 0.65) • Reactions to Vehicle Loading • Maximum Vertical Reaction Non-dimensional Reaction Force

30. (Special Consideration on Cracks & Spalls in Pier Cap) • Possible Reasons for Cracks & Spalls • Largest reaction force • Missing of vertical & lateral wrapping reinf. • Concrete cover thickness < 2” missing

31. Intervention for Repair • Outer Girders • Removing Rust and painting is needed to prevent further corrosion and sectional loss • Bearings under outer girders • Severely corroded bearings should be changed for proper movement by thermal expansion • Abutments • Severe cracks and inclination due to structural deficiency • Hard to decide the safety of Abutments at this time • Need to monitor the behavior of abutments using crack meters and inclinometers