Fatigue Testing and Design of Large Diameter Shear Studs Used in Highway Bridges

Abstract

Headed studs are commonly used to transfer shear forces along the interface of the steel beam and concrete deck in composite highway bridge girders. Typical stud diameters used in composite bridge design are less than 1". Because of the need for bridge decks to be replaced quickly, using fewer studs with larger diameter (1¼") would be beneficial in accelerating the construction. Before being put into use, these large diameter studs must be tested to ensure that they perform adequately and meet current fatigue design provisions in AASHTO LRFD (2007). An experimental test program was carried out that tested a total of 24 push-out specimens. Twelve specimens had shear studs with a large diameter of 1¼", and the other twelve had shear studs with a standard diameter of 7/8". Shear stress ranges of 18, 22, and 26 ksi were used. Based on the research presented in this thesis, the 1¼"-diameter studs performed equally as well as the 7/8"-diameter studs and can safely be designed using the current fatigue design provisions of AASHTO LRFD (2007).