Stochastic Pattern of Structural Strength of Structures Under Wave Load : Stochastic Pattern of Crack Propagation

Abstract

The design concept of occean structures is now changing from the "design by rules" concept to the "design by analysis" concept, where starting from load analysis, various kinds of analyses such as stress-analysis and failure analyses are carried out in a same flow. And it can be pointed out as a special feature of the "design by analysis" concept that safety of structures is estimated from probabilistic points of view instead of the decisive estimation which has been adopted for long time. Carrying out probabilistic estimation of structural safety it is necessary to handle the two kinds of probability, the probability of stuctural strength which is originated from randomness of external load, and the probability of material strength caused by scatterness of material qualities. The author et al have been investigating problems mainly as to the former probability and have reported parts of the investigations. And in the present report, crack propation phenomena under random wave load are studied from stochastic point of view, that is, firstly methods of probabilistic estimation as to crack propagation are introduced base on the present states of art in crack propagation analysis, secondly, feasibility of the methods is verfied by numerical experiments, simulation of crack propagation under random load by computor, lastly, consideration is carried out to clarify stochastic pattern of crack propagation based on the methods derived.