1. Adjunct Assistant Professor, Dept. of Civil Engineering, Tamkang Univ., E729, #151 Ying-Chuan Rd., Tamsui, Taipei, Taiwan 251. E-mail: 123562@mail.tku.edu.tw
2. Professor, Dept. of Civil Engineering, Tamkang Univ., E732, #151 Ying-Chuan Rd., Tamsui, Taipei, Taiwan 251 (corresponding author). E-mail: yinghaur@mail.tku.edu.tw