Unless damaged by frequent earthquakes or water seeping into the structure and corroding the steel, or freeze-thaw cycles, reinforced concrete does not degrade

Unless damaged by frequent earthquakes or water seeping into the structure and corroding the steel, or freeze-thaw cycles, reinforced concrete does not degrade significantly with age. The range you quote is more typical to things like concrete infrastructure directly exposed to the elements. Modern HPC concrete structures can be guaranteed for 100 years with proper maintenance and will probably have a natural life of multiple centuries.