A comparison of stochastic process models for definition of design contours

So-called design contour methods are frequently applied for large and complex structures in order to minimize the number of time-consuming structural analyses. These methods are based oil first identifying extreme environmental conditions with it given probability of exceedance based oil the relevant joint distribution function. These conditions are located along it level surface (i.e. contour) in the space of load parameters. As the second step, response analyses are performed for a selection of extreme conditions which are located along this contour. The highest response level which is obtained its a result of these analyses is then applied for design purposes. This approach is based on a representation of the underlying stochastic processes in terms of a sequence of piecewise constant levels. In the present paper, the extreme environmental conditions which are obtained based oil such a model are compared to those obtained by instead applying a continuous process model. Furthermore, various alternative and relevant definitions of design contours are compared for the two-component case. In the present analysis, mainly stochastic processes which represent load parameters are considered. However, the approach for identification of level surfaces is of it general nature and can be applied to any types of random vector processes. (C) 2007 Elsevier Ltd. All rights reserved.