Chimneys in operating power plants cannot be demolished in the classical way by dynamite. A new technology has been invented where they are cut off starting from the top and where the pieces of the reinforced concrete chimney are dropped through the inner pipe of the chimney. In order to avoid the falling down of pieces on the outer side, a ring platform is attached to the chimney by pure force contact, which allows semi-automatic climbing up and down. The paper addresses two crucial design decisions concerning the ring platform: the design of the contact geometry and the shape of the ring structure. Both design problems are formulated as multicriterion optimization problems where the first one can be solved partially in an analytical way whereas the second one has to be solved numerically. It will be shown how the problems can be formulated in various ways depending on the technical requirements.