1. Research Institute of Structural Engineering and Disaster Reduction, College of Civil Engineering, Tongji University, Siping Road, Shanghai 200092, P. R. China
2. Department of Civil Engineering, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku Nagoya 468-8502, Japan
3. Department of Structural Engineering, College of Civil Engineering, Tongji University, Siping Road, Shanghai 200092, P. R. China