1. Professor, Dept. of Construction Engineering, National Kaohsiung Univ. of Science and Technology, 1 University Rd., Yanchao, Kaohsiung, Taiwan 824, ROC (corresponding author).
2. Ph.D. Student, Institute of Engineering Science and Technology, National Kaohsiung Univ. of Science and Technology, 1 University Rd., Yanchao, Kaohsiung, Taiwan 824, ROC.