1. Professor, Dept. of Mechanical Engineering, Univ. of Thessaly, 383 34 Volos, Greece; Professor, School of Engineering, Univ. of Edinburgh, Edinburgh EH9 3FG, U.K. (corresponding author).
2. Graduate Research Assistant, Dept. of Mechanical Engineering, Univ. of Thessaly, 383 34 Volos, Greece.
3. Chief Engineer, Northwest Pipe Company, Vancouver, WA 98661.
4. Chief Pipe Engineer, Lockwood, Andrews & Newnam, Inc., Houston, TX 77042.