Steel transverse beam on The Metropolitan Expressway , Japan.
Fatigue cracks were found in welded joints of diaphragms which were under girder supports.
Steel transverse beam with box section.
Fluctuating loads due to highway live load.
Fatigue cracks location are shown in Fig.1.Photograph of Type1-crack is shown in Fig.2.Photograph of Type2-crack and Type5-crack are shown in Fig.3
Causes of fatigue cracks were as follows:
- Stress consentration due to sudden change in rigidity.
- Local deformation at the scallop.
Emergency repair
Stop holes were drilled at the crack tips.
Kinomoto et al,A study on The Fatigue Cracks at Welded Joints of Transverse Beam Diaphragms which were Under Girder Supports ,Prc.of Annual Conferenece of JSCE,vol.59,2004.(In Japanese)