Evaluation of safety of structures with fuzzy parameters

This paper presents a method for evaluating the safety of structures with fuzzy input parameters. Uncertainty in load and material properties is defined by triangular membership functions with equal spread about the crisp value. The structure is modeled using the fuzzy finite element approach developed earlier by the first author. The structural response is obtained in terms of fuzzy interval displacements and rotations. The results are further postprocessed to obtain interval values of bending moment, shear force and axial force. Combined membership functions for uncertain forces in the elements are obtained using the α-sublevel approach using this interval output. Fuzzy membership functions of stresses in the elements are evaluated and are compared with the corresponding membership functions for the allowable stresses. Safety of the structures is evaluated at various levels of uncertainty of the input parameters. The present work demonstrates the effectiveness of uncertainty based analysis and design in establishing reliability of structural design for a structure with uncertain input parameters.status: publishe