1. School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA, Telephone: 1/404-894-2284, Telefax: 1/404-894-2281,
2. School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-1284, USA, Telephone: 1/317-494-5031, Telefax: 1/317-496-1364,