Resistance of headed studs subjected to fatigue loading Part II: Analytical study

Most design codes consider the static and fatigue resistance of composite steel-concrete structures with separate verifications for ultimate limit state and the limit state of fatigue. For headed shear studs both verifications are based on worldwide performed experimental investigations with push-out specimens. The determination of the fatigue life of headed shear studs in recent European codes is based on the S-N curve developed from the statistical analysis of a great number of cyclic push-out tests. The S-N curve considers the shear stress range as the only loading parameter. In addition, the maximum shear force is limited at serviceability limit states in order to avoid significant inelastic behaviour. However, recent researches showed that beside the shear stress range, also the peak load and the static strength of the shear studs influence the fatigue life. Based on the results of the 71 push-out tests presented in the earlier companion paper, international push-out tests to determine the fatigue life of headed shear studs in solid concrete slabs are sorted and reanalyzed and analytical expressions are developed to predict the fatigue life and the reduced static strength after high cycle preloading. Furthermore, the linear damage accumulation hypothesis according to Palmgren and Miner is modified and improved to consider load sequence effects and non-linear behaviour.