Abstract：Through the traditional response analysis method for uncertain structures based on non-probabilistic convex model, only the bounds can be obtained. So, in this paper a new uncertainty propagation method which combined volume ratio with first order second moment is proposed. Using this uncertainty propagation method, not only the bounds but also the pseudo-probability distribution of the structural response can be accurately evaluated. First, the uncertainty of structure parameter is modeled by multidimensional ellipsoid convex set. The ellipsoid is separated two parts by the state equation of the structural response with respect to uncertain parameters. So, the volume ratio of separated domain and the whole ellipsoid domain can be used to quantify the uncertainty of structural response. Second, in order to obtain the most probable expansion point and the approximate volume of the separated domain, the propagation equation of uncertain response is sequentially solved through First order second moment (FOSM) method. Finally, the uncertain response analysis of a typical six-bar truss is applied using the proposed method, Monte Carlo simulation and traditional method. The comparisons of the results demonstrate that the proposed method is more effective and accurate.
2015, Vol. 36 
