1. Ir., Res. Asst. IWT, Magnel Lab. for Concrete Res., Dept. of Struct. Engrg., Ghent Univ., Technologiepark-Zwijnaarde 9, B-9052 Gent, Belgium. E-mail: Stijn.Matthys@rug.ac.be
2. Prof. Dr. Ir., Magnel Lab. for Concrete Res., Dept. of Struct. Engrg., Ghent Univ., Technologiepark-Zwijnaarde, 9, B-9052 Gent, Belgium.