How is fatigue considered in concrete structure design?

Concrete fatigue is relevant for bridges, crane girders, and machine foundations. Design approaches: (1) S-N relationships - stress range vs number of cycles to failure (concrete fatigue strength is 50-60% of static strength at 2 million cycles), (2) Miner's rule for variable amplitude loading, (3) Modified Goodman diagram for mean stress effects. Factors include: stress range, minimum stress level, loading frequency, concrete strength, and age. Reinforcement fatigue at cracks and bond fatigue also considered. Conservative approach uses endurance limits below which infinite life assumed.