1. Professor Emeritus, Zienkiewicz Centre for Computational Engineering, Swansea Univ., Swansea SA1 8EN, UK (corresponding author).
2. Professor, Dept. of Civil Engineering, McMaster Univ., Hamilton, ON, Canada L8S 4L7.
3. Project Engineer, Rockfield Software Ltd., Kings Rd., Swansea SA1 8AS, UK.