1. School of Civ. and Envir. Engrg., Univ. of Edinburgh, The King's Buildings, Edinburgh EH9 3JN, U.K.
2. Reader, School of Civ. and Envir. Engrg., Univ. of Edinburgh, The King's Buildings, Edinburgh EH9 3JN, U.K. E-mail: jin@srv0.civ.ed.ac.uk
3. Lect., School of Civ. and Envir. Engrg., Univ. of Edinburgh, The King's Buildings, Edinburgh EH9 3JN, U.K. E-mail: mholst@ed.ac.uk
4. Prof., School of Civ. and Envir. Engrg., Univ. of Edinburgh, The King's Buildings, Edinburgh EH9 3JN, U.K. E-mail: michael@srv0. civ.ed.ac.uk