Optimal Placem en t of Sem i-active Con trol D ev ices for Con trolled Structure BE IW ei2m ing, L I Hong2nan (Sta te Key L abo rato ry of Coasta l and O ffsho re Engineering, D alian U niversity of T echno logy, D alian 116024, Ch ina) Abstract: T he structu ra l vib ra t ion con tro l u sing dampers can reduce the respon ses of the st ructu res in2 duced by ground mo tion effect ively. How ever,