The eigenvalue optimization problem for a variational inequality over the c
onvex cone is to be dealt with. The control variable appears in the operato
r of the unilateral problem. The existence theorem fbr the maximum first ei
genvalue optimization problem is stated and verified. The necessary optimal
ity condition is derived. The applications to the optimal design of unilate
rally supported beams and plates are presented. The variable thickness of a
construction plays the role of a design variable. The convergence of the f
inite elements approximation is proved. Copyright (C) 2001 John Wiley & Son
s, Ltd.