1. School of Civil & Architecture Engineering; Xi'an Technological University; Xi'an 710032 China
2. Department of Architectural Engineering; Yonsei University; 134 Shinchon-dong, Seodaemun-gu Seoul 120-749 Korea
3. Department of Civil, Environmental, and Geodetic Engineering; The Ohio State University; 470 Hitchcock Hall, 2070 Neil Avenue Columbus OH 43220 USA