1. David Ross Boyd Professor, Aaron Alexander Professor, Associate Dean for Research, College of Engineering, Univ. of Oklahoma, 202 W. Boyd St., Rm. 107, Norman, OK 73019 (corresponding author).
2. Doctoral Candidate, School of Civil Engineering and Environmental Science, Univ. of Oklahoma, Norman, OK 73019.
3. President, Burgess Engineering and Testing, Inc., 2603 N. Shields Blvd., Moore, OK 73160.
4. Professor, Dept. of Mathematics, Univ. of Oklahoma, 601 Elm Ave., Norman, OK 73019.