Abstract
Robinson type composite deck, in which concrete and a base steel plate stiffened with transverse ribs are connected by headed studs, is a typical and major one among composite decks in Japan. Through the past fatigue tests for the composite decks under running wheel load, fatigue failure of the studs was confirmed to be an important phenomenon and to be designed based on reasonable fatigue data. Then the fatigue tests on an isolated stud by giving rotating shear force were carried out and a fatigue design method was proposed in 1997. Shortly afterwards, fatigue test machine giving a rotating shear force was improved and new fatigue data were obtained. Furthermore, welding method of the stud was also improved to increase fatigue life by improved welding ferule. The new data with the improved ferule have shown about 3 times longer fatigue lives from the ordinary ferule.
In this study, analytical investigations were carried out on two points. The first one is to get a reliable fatigue design method of the studs in the composite deck on the relation between the fatigue data of studs in a composite deck under wheel running machine and the S-N data of studs obtained from the recent rotating shearing fatigue tests on isolated stud. The second one is proofing the fatigue life elongation by changing welding methods using new ferule from the ordinary one. The both analytical investigations are based on the shearing stress analysis at the welding boundary of welded stud and a base steel plate. Three dimensional FEM analyses were carried out with detailed modeling of the welded collar shape and the above mentioned numerical investigations were obtained with the higher reliability.
