1. Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125 Perugia, Italy
2. Department of Continuum Mechanics and Structural Analysis, School of Engineering, University of Seville, Camino de los Descubrimientos s/n, 41092 Seville, Spain
3. Department of Mechanics, University of Cordoba, Campus de Rabanales, 14071 Cordoba, Spain
4. Department of Civil, Construction, and Environmental Engineering, Iowa State University, 394 Town Engineering, Ames, IA 50011, USA