[1] Univ Parma, DICATeA, Parco Area Sci 181-A, I-43124 Parma, Italy
[2] Cervenka Consulting, Prague, Czech Republic
[3] Delft Univ Technol, Fac Civil Engn & Geosci, Stevinweg 1, NL-2628 CN Delft, Netherlands
[4] Norwegian Univ Sci & Technol, Dept Struct Engn, Rich Birkelandsvei 1A, N-7491 Trondheim, Norway