Figure 3
The diagram shows a schematic stiffness matrix K, presented in a square shape. The matrix is divided by a thick diagonal strip extending from the top-left corner to the bottom-right corner. The dots are marked near the top-left and bottom-right corners, which are labeled “K subscript P R.” The middle portion of the diagonal strip is enclosed in a dashed square. Within the dashed square, two hatched squares are positioned at the top left corner, labeled “K subscript I R, 1,” and at the bottom left corner, labeled “K subscript I R, 2.” The small square is positioned at the center with a dot at its center and labeled “K subscript A D.” A dot is marked on the right side of the square labeled “K subscript S E.”Schematic stiffness matrix of the reduced discretized model. Filled regions denote entries, which are not necessarily zero. In this setup the optional dimension expansion of KSE is depicted. The shaded regions, KIR,i with i = [1,2], are part of KPR and KRR due to addition of elements which refer to ΓIR. KSE extends over the entire light grey region. Source: Authors’ own work