1. Department of Civil and Environmental Engineering, University of Auckland Private Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand Telephone: +64 9 373 7599 ext. 89067, Telefax: +64 9 373 7462,
2. Department of Civil Engineering, Building 60, Monash University Vic. 3800, Australia Telephone: +61 3 9905 4956, Telefax: +61 3 9905 4944,(corresponding author)
3. Department of Civil and Environmental Engineering, University of Missouri-Columbia Columbia, MO 65211-2200, USA Telephone: +1 573 882 4784, Telefax: +1 573 882 4784,
4. Department of Civil and Environmental Engineering, Polytechnic University of Puerto Rico PO Box 191234, San Juan, PR 00919-1234, Puerto Rico Telephone: +1 787 529 4207, Telefax: +1 787 771 0011,