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Sample? (2014-03-20 (Thu) 05:40:08)
1. Field of application
Steel pier at the third line of The Metropolitan Expressway, Japan.
2. Circumstance of repair
Fatigue cracks were found in welded joints ,which were at the corner of the steel bridge pier,in 1997.
3. Types of structure
Front views of the steel piers are shown in Fig.1.
Fig.1 Front of the steel piers
4. Details of loading
Fluctuating loads due to highway live load.
5. Description of damage
One of these fatigue cracks location and detail are shown in Fig.2.
Fig.2 One of these fatigue cracks location and detail
Causes of fatigue cracks were as follows:
・Lack of fusion in the double bevel groove type welded joint which connected the transverse beam flange to the colum flange.
・Large cyclic stress due to live load.
6. Repair method applied
As the temporally-repair,bolted splice plates were installed on the box webs of the connections.This repairing decreased the measured stress by about 50%,so that these piers could be used safely temporally.But it was needed to remove all the fatigue cracks as the final repair.
Fig.3 Bolted splice plates
Fig.4 Construction photograph of bolted splice plates
Reference
Hisashi MORIKAWA,Tetsuhiro SHIMOZATO,Chitoshi MIKI and Atsushi ICHIKAWA,STUDY ON FATIGUE CRACKING IN STEEL BRIDGE PIERS WITH BOX SECTION AND TEMPORALLY REPAIRING,Journal of JSCE,No.703/I-59,pp177-183,2002.4(In Japanese)
