The extension of the weighted integral method, in the field of stochastic finite element analysis, is represented. The local integral method in stochastic analysis was introduced by Takada and Shinozuka(1989) and Deodatis(1990). They made use of the weighted integral to the field over an element in deriving the element stiffness matrix. he usage of weighted integral method, in numerical analysis, was extended to CST(constant strain triangle) element by Deodatis to calculate the response variability of 2D stochastic systems.
In this paper, the extension of the weighted integral method to general quadrilateral elements is represented. The random variables generated by the integral of random field function are transformed into only one integral term. So the inclusion of stochastic FE analysis to the ready made programs can be made easily.
Due to the represented method, the same mesh used in the deterministic FE analysis can also be used in the stochastic FE analysis. Furthermore, because the CST element is a special case which has constant strain-displacement matrix, with the represented method, the mingling of the CST elements with the other quadrilateral elements in the analysis may be possible.