1. Professor, School of Civil Engineering, Univ. of Burgos, 09001 Burgos, Spain (corresponding author).
2. Professor, School of Civil Engineering, Univ. of Burgos, 09001 Burgos, Spain.
3. Professor and Chair, Dept. of Civil, Architectural, and Environmental Engineering, Illinois Institute of Technology, Chicago, IL 60616; formerly, Changjiang Scholar Chair Professor, Chinese Education Ministry, Tongji Univ., Shanghai 200092, China.