Question
While design life will it be same as return period for design situations?
Answer
Design life means least duration a structure is accepted to last. Longer is design life; so higher is cost of a project. So, while choosing design life for a structure, engineers have to consider design life that generates an economical project without sacrificing necessary function.
During selection of return period of convinced design conditions, winds, waves. One should think consequences of exceedance. In reality, there are usually no extreme maximum values of these plan conditions and its variety is based on probability of exceedance that is related to return time.
So, design life might not be like to return time of design conditions while their ranges are based on diverse considerations.