The response variability of structures is generally caused by random loading and/or random structural properties. Recently, attempts to deal with interpretation of material properties as a problem of random fields have received considerable interest from engineers and researchers, and the finite element analysis combined with a Monte Cairo simulation technique or perturbation method has been proposed to evaluate the response variability of structures. In this paper, the response valiability of

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... inear structures under spatial variation of elastic properties (in this case, flexibility) is investigated. Utilizing a Green's function formuration, the mean square statistics of statically determinate beams and, more importantly, statically indeterminate beams are determined in a simple integral form which can be readily evaluated by the numerical method in negligible computer time. Using the fixed end beam model under uniform loading, the response variabilities of beam end moment and deflection were expressed in terms of random variables which were mutually correlated and were evaluated using the First-Order Second-Moment method. Due to the generality of the present approach, it seems feasible to treat a larger system (e.g. multi-bay/multi-story frames) with acceptable numerical effort. Finally, the safety indices for the beam midspan deflection and end moment were evaluated using two standard method (i.e. Lagrange's multiplier method and Advanced First-Order Second-Moment method).