STOCHASTIC ASSESSMENT OF STRUCTURAL SYSTEMS SUBJECT TO RANDOM VECTOR OF COMBINED LOADS

Abstract

In this paper, the reliability assessment of structural system (a pipeline) subject to a combination of loads described as random Markov processes is presented. This method assumes the ability of constructing admissible areas in the load space with respect to different limit states. The method is applied to a segment of an above ground oil pipeline with surface corrosion type defects subjected to a combination and simultaneous action of four loads: dead weight of the pipe with insulation and oil being pumped; operating pressure; wind load and exposure to a uniform wall thickness thinning. The pipeline is considered as a continuous multi-bay thin wall cylindrical beam. The pipeline design is performed according to the (conditional) limit state which is reached when the equivalent stresses in pipe wall reach the yield stress of the pipe material. The specifics of the developed approach are that it splits the task of evaluating the reliability into two independent tasks, namely, constructing admissible areas in load space, and assessment of the probability of escape of the vector load from the admissible region.