Fuzzy-based integrated zero-order shape optimization of steel–concrete–steel sandwich beams

This study presents a fuzzy-based integrated zero-order approach for shape optimization of steel–con­crete–steel (SCS) sandwich beams. The method works on the novel idea of changing the shape of faceplates and core at the interface without affecting the overall shape of the beams. The proposed zero-order shape optimization technique is based on perpendicular growth and shrinkage in the design boundary at the interface of the faceplate and core to obtain an opti­mized shape. The concept of ‘design elements’ has been used to avoid mesh distortion. Automatic mesh generation and refinement are incorporated at each iteration. Fuzzy set theory is used to control the move­ment of nodes and convergence monitoring. A target maximum shear stress value (st) is taken up and the shape is changed such that maximum shear stress (s) at any point is smaller than or equal to the st. For this, fuzzy membership functions in the form of triangular shape function have been used. The proposed approach coded in FORTRAN is labelled as gradientless shape optimization (GSO). It is found to perform effectively in determining the optimized shape of faceplates and core. To explain the efficacy of the proposed method, a few examples have been taken with changing boundary conditions and shape of the SCS sandwich beam