Are the stiffness terms in "Exact stiffness matrix for beams on elastic foundation" by Moshe Eisenberger, David Z. Yankelevsky (1985) correct?

09 December 2024 0 3K Report

The stiffness term S11 in equation (6a) goes negative for lambda*L > pi/2. As this term links the displacement at x=0 to the load at x=0, it should always be positive, regardless on the length of the beam. Am I missing something?

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