The vectors w1 ¼ ½w1
1; w2
1; …; wn
1
T and w2 ¼ ½w1
2; w2
2; …; wn
2
T contain the nodal displacements and angles of rotation. m, c
and k are sparse matrices, almost zero, with a suitably localized parameter of concentrated mass m, damper c and spring k,
respectively. Moreover, we assume a small value of the internal damping of the beams Cb although it does not influence the
results in a visible scale, since it is significantly smaller than the damping of the coupler c.