NDT by Infrared Thermography and Repair by TRS for Fatigue Cracks

Transcription

1 NDT by Infrared Thermography and Repair by TRS for Fatigue Cracks Atsuhiro Okumura Honshu-Shikoku Bridge Expressway Co. Ltd. Engineer ORGANIZATION OR COMPANY LOGO

2 Contents of Presentation 1. Introduction of Honshu-Shikoku Bridges 2. Fatigue inspection with infrared thermography Principle of fatigue crack detection method Measurement in a bridge Development of practical application system 3. Repair method by TRS Current situation of repair methods Developed repair method Fatigue test Test result 4. Conclusion

3 1. Introduction of Honshu-Shikoku Bridges

4 Honshu-Shikoku Bridge Project N S Hokkaido Honshu JAPAN (Nippon) Honshu Tokyo Hiroshima Osaka HSBE Shikoku Kyushu Four major islands in Japan were linked by bridges/tunnels by the end of 20 th century. Nishi-Seto Expressway Legend: Seto-Chuo Expressway Shikoku Kobe-Awaji-Naruto Expressway Honshu-Shikoku Bridge Expressway West Nippon Expressway and others

5 Honshu-Shikoku Bridges Kobe-Awaji- Naruto Expressway Akashi Kaikyo Bridge Ohnaruto Bridge 10 suspension bridges 5 cable-stayed bridges 1 arch bridge 1 truss bridge 17 long-span bridges in total Seto-Chuo Expressway Shimotsui-Seto Bridge Hitsuishijima/Iwakurojima Bridges Kita/Minami Bisan-Seto Bridges Nishi-Seto Expressway Innoshima Bridge Tatara Bridge Kurushima Kaikyo Bridges

6 Introduction Asphalt pavement Deck Plate Longitudinal Pavement Weld root Deck Plate Trough rib Cross girder Main girder Bead-penetrating Crack The developed inspection method and repair method are for weld-bead-penetrating cracks.

7 2. Fatigue inspection with infrared thermography

8 Principle of fatigue crack detection method Temperature gap method T Temperature profile A B b a x pixel without crack with crack Trough Rib 6 or 8mm b Asphalt Pavement 65mm Deck Plate B 12~14mm Temperature profiling line Infrared thermography Fatigue crack a A

9 Measurement in a bridge Down Line Up Line Maintenance Vehicle for Outside Girder Maintenance Vehicle for Outside Girder Used infrared camera on the moving maintenance vehicle at 250mm/sec (0.9km/h).

10 Measurement in a bridge Temperature image Actual image A B Line Line

11 Measurement in a bridge Temperature image Actual image A B Line Line

12 Measurement in a bridge Temperature image Actual image A B MT result Line Line crack

13 Development of practical application system Camera system Consist of a rail, a cart, an infrared camera, and a controller such as PC. Can record continuous temperature images by the movement of itself. Infrared camera Cart PC Wireless connection

14 Development of practical application system Camera system Orthotropic steel deck Infrared camera PC rail cart

15 Development of practical application system Crack detection system Temperature image Numerical processing image crack crack Temperature profile Max and min of derivative

16 3. Repair method by TRS

17 Current situation of repair methods Method Re-welding Plate-splicing with stud bolts Plate-splicing with HTB Outline Remove crack, and repair by re-welding Transmitting stress with splicing plate instead of welded joint. Execution from only the underside Transmitting stress with splicing plate instead of welded joint. Execution with removing pavement Pavement Remove welded joint Stud bolt (φ19) S10T(M20) Splicing Plate MUFT20 Build-up welding 積層溶接接合部には向けない MUFT20 Remarks Welding in an upward direction, Traffic vibration Difficult quality control Reappearance of cracks Upward welding for stud bolt Possible of crack from welded toe Removing pavement is needed Possible of degrading waterproofing performance So, no effective method from the underside of the deck was developed although several repair methods were proposed

18 Developed Repair Method Deck Plate Pavement Splicing Plate Trough rib Pavement Deck Plate Trough rib Splicing Plate MUTF20 HTB TB or TRS Splicing Plate Bolt length and depth of bolt hole are controlled so that pavement is not damaged Method and Merit Bearing-type connection with Tap Bolts(TB) or Thread Rolling Screws(TRS). Bolt holes are made from the underside. TRS is no need to form female threads. No need of traffic restriction and removal of the pavement Applicable from underside of the deck

19 Fatigue Test (Test Model and Applied Load) Applied load: 260kN/axle Loading patterns: (a)direct loading (b)in-between loading Detail L1(HTB) L2(TB) L3 L4(TRS) Thread Rolling Screw(TRS) Remarks Friction joint Bench mark for evaluation (Existing repair method) Work from both sides of the deck Bearing-type connection Applicable from underside of the deck Need to form female threads Bearing-type connection Applicable from underside of the deck No need to form female threads

20 Fatigue Test Fatigue test is tested with the following condition No. Case Condition Loading pattern 1 Corrective maintenance 2 Preventive maintenance Bead-left case Bead-cut case Deck plate Plate splicing is conducted AFTER crack is generated. Plate splicing is conducted BEFORE crack is generated. Splice plate is applied to original weld bead. Splice plate is applied to cutting weld bead in order to eliminate root where crack initiate. cutter Deck plate cutter Before crack is generated: Direct loading 3 million times After plate splicing: Direct loading 2 million times Test Model 2 Direct loading 3 million times In-between loading 2 million times Test Model 1 Direct loading 3 million times Test Model 2 Direct loading 3 million times In-between loading 2 million times

21 S0 S600 S1200 Test Result Corrective maintenance case (Test Model 2) Unit:mm Unit: mm L1 : HTB L2 : TB L3 : TRS L4 : TRS L1 L2 L3 L (5.0) (1.2) 39.0[24.0] [(2.0)] [(1.0)] (3.0) [(3.0)] (5.1) [(1.7)] 5.9 [(1.2)] 52.0 (3.1) (1.6) [(1.0)] [(2.1)] [(1.6)] (3.0) 9.1 [(1.2)] [(3.0)] [(5.8)] bead crack* loading position deck crack** *( ) shows internal crack length in beads. [ ] shows crack length measured after generation of bead-penetrating crack. ** Crack length measured after all loading cases from bottom side of deck. top Bead cracks grow at many locations, and deck cracks are found. It is found that cracks may progress if plate splicing is applied without bead cut.

22 Test Result Preventive maintenance case (Test Model 2) Unit: mm L1 : HTB L2 : TB L3 : TRS L4 : TRS 77+ direct loading position In-between loading position bead cut bead crack deck crack 81+ top Both bead cracks and deck cracks are found at plate splicing without bead cut. No cracks are found where beads are cut although some are found at the end of bead cut. From these, bead is better to be removed.

23 Test Result Preventive maintenance case (Test Model 1) No cracks are found. deck plate cutter L1:HTB L2:TB L3:TRS L4:TRS cutter 23

24 4. Conclusion

25 Fatigue inspection with infrared thermography The remote crack detection method by the temperature gap using infrared thermography can detect cracks under the heavy-duty coating without removing the coating. By the camera system, efficient measurement is possible. By the crack detection system, efficiency and reliability of crack detection is improved. In Honshu-Shikoku Bridge Expressway, the inspection for fatigue shall be done effectively and efficiently, with the developed system and the manual.

26 Repair method using TRS Bead cracks and deck cracks can be suppressed if plate splicing is applied with bead cut. For three connection methods (HTB, TB, and TRS), there were not bolt loosening and cracks from bolt holes. From the view point of workability, TB and TRS can be applied from the underside. Especially TRS has advantage over TB since shaving process can be omitted.

27 Thank you for your kind attention!