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Shonan Br. of R-134 in Kanagawa, Japan.
The holes of the pavement due to the fatigue cracks of orthotropic deck plates were found in September of 1999 after 13 years of service. And 322 cracs were found by inspection of the bridge. Then, repair with the reinforcement plates on the deck plates were applied. Furthermore, 122 cracks were found in the welded joint between longitudinal trough ribs and deck plates by inspection in 2003.The 122 cracs were repaired by welding.
The outline of the bridge structure is as follows.
- Bridge length : 2 × three spans : (3＠88.0m)
- Structure : Three spans continuous orthotropic steel plate deck two box-girder bridge.
- Deck plate thickness : 12～20mm
Shonan bridge is shown in Fig.1.
Fig.1 Shonan bridge
Fluctuating loads due to vehicles live load. 3700 vehicles / 24hr. truck ratio : 18% in 2006
The fatigue cracks were detected on welded joints between longitudinal trough ribs and orthotropic deck plates.Type-1 cracks were the cracks to penetrate the deck plates.Type-2 cracks were the cracks along the welded joints.
Fig.2 Crack location
Cause of fatigue cracks was as follows:
- Localized stress concentration which resulted from the out-of-plane of the deck plate deflection due to the wheel load.
Emergency repair
The reinforcement plates on the deck plates(Fig.3) were applied for the Type-1 cracks with more than 6mm of depth.
Type-2 cracks were repaired by welding.
Fig.3 Reinforcement plate (t=12mm) on the deck plate
Permanent repair
The SFRC pavements were constructed on the orthotropic deck plates instead of asphalt pavements.(Fig.4).And the change of the driving lane was carried out to move a wheel position and a fatigue damage point.
Fig.4 The typical cross-section of SFRC
NIKKEI CONSTRUCTION,2006.3.24,pp65-67
Kodama et al,Replacement of Pavement with SFRC to Improve Fatigue Characteristics of the Damaged Orthotopiic Steel Decks,Bridge and Foundation Engineering,vol.40,No.11,pp.30-38,2006.11(In Japanese)
