Primary objective of this report is to provide a fundamental strategy to analyze dynamic response of offshore structures under collision. The key to planning meaningful experiments or numerical analyses is a classification of the given problem based on the overall knowledge of the phenomena. The authors proposed a method in which offshore structures are idealized as spring-mass systems. The characteristics of the collision problems were studied to get the overall knowledge using this method. Such knowledge can be utilized to classify given problems and also to decide how to tackle them. Following the above strategy, collision problems of single pipe and an elastically supported pipe were analyzed using beam and shell Finite Element Methods as examples.