1. Assistant Professor, Dept. of Mechanical and Industrial Engineering, Univ. of Toronto, 5 King’s College Rd., Toronto, ON, Canada M5S 3G8; Assistant Professor, Dept. of Civil and Mineral Engineering, Univ. of Toronto, 5 King’s College Rd., Toronto, ON, Canada M5S 3G8 (corresponding author).
2. Professor, Dept. of Structural Engineering, Univ. of California-San Diego, La Jolla, CA92093.