1. Seismic Isolation Engineering, Inc., Oakland, CA; formerly, Ph.D. Candidate, Dept. of Civil and Environmental Engineering, Univ. of California, Berkeley, CA 94720. E-mail: black@siecorp.com
2. Professor, Dept. of Civil Engineering, Univ. of Patras GR-26500, Greece; and Research Engineer, Earthquake Engineering Research Center, Univ. of California, Berkeley, CA 94720. E-mail: nmakris@upatras.gr