1. Member, ASCE
2. Res. Asst., Dept. of Engrg. Sci. and Mech., Virginia Polytechnic Inst. and State Univ., Blacksburg, VA, 24061. E-mail: dstamos@vt.edu
3. Assoc. Prof., Dept. of Engrg. Sci. and Mech., Virginia Polytechnic Inst. and State Univ., Blacksburg, VA. E-mail: mhajj@vt.edu