1. Assistant Professor, Dept. of Structural Engineering, Univ. of Calabria, Rende, CS, 87036 Rende, Italy. E-mail: f.bencardino@unical.it
2. Ph.D. Candidate, Dept. of Structural Engineering, Univ. of Calabria, Rende, CS, Italy. E-mail: l.rizzuti@strutture.unical.it
3. Professor, Dept. of Structural Engineering, Univ. of Calabria, Rende, CS, Italy (corresponding author). E-mail: g.spadea@unical.it
4. Professor Emeritus, Dept. of Mechanical Engineering, Univ. of Sheffield, S13JD Sheffield, U.K. E-mail: R.N.Swamy@sheffield.ac.uk