1. Professor, Dept. of Civil Engineering and Architecture, Univ. of Catania, Viale Andrea Doria 6, 95125 Catania, Italy (corresponding author).
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Perugia, Via G. Duranti 93, 06125 Perugia, Italy.
3. Civil Engineer, Idragest S.r.l., Via Santa Sofia 65, 95123 Catania, Italy.
4. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Perugia, Via G. Duranti 93, 06125 Perugia, Italy.
5. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Perugia, Via G. Duranti 93, 06125 Perugia, Italy.
6. Civil Engineer, Studio Chiarini Associati–Ingegneria Civile e Ambientale, Via Galileo Ferraris 63, 52100 Arezzo, Italy.