1. Professor, Dept. of Civil and Environmental Engineering, National Univ. of Singapore, Kent Ridge, Singapore 119260.
2. Graduate Student, Dept. of Civil and Environmental Engineering, National Univ. of Singapore, Kent Ridge, Singapore 119260 (corresponding author).
3. Professor, Université Européenne de Bretagne, Univ. of South Brittany UBS, UBS LIMATB, Centre de Recherche, Rue de Saint Maudé, BP92116, 56321 Lorient cedex, France.
4. Professor, School of Computing, Engineering and Mathematics, Institute for Infrastructure Engineering, Univ. of Western Sydney, Locked Bag 1797, Penrith, NSW 2751, Australia.