Fatigue Capacity of Concrete Subjected to Partially Loaded Areas

Abstract

The compressive strength of concrete at bearing areas is increased due to the confinement of surrounding concrete and reinforcement. In these partially loaded areas, local crushing and transverse tension forces must be considered. Design codes propose criteria for the concentrated resistance force for static loading but not specifically for dynamic loading. In this study, 102 concrete specimens were tested statically, and 22 concrete specimens were tested dynamically. The effect of steel fibers on the fatigue performance of concrete and the effect of submerged specimens in water were investigated. To simulate a wind turbine foundation, the tested specimens were confined in one direction by applying threaded bolts, while the load was free to spread in the other direction. As expected, transverse reinforcement and fibers increase both the static and fatigue capacity. The static capacity increased with a factor of 1.4-2.0 depending on the environmental condition. Most design codes do not consider the environmental condition, i.e., the reduced fatigue capacity due to the water submergence of concrete structures. Based on the experimental result, a new environmental factor was proposed for a partially loaded area subjected to cyclic loading, which can be taken in the DNV design code’s formulation.