1. Professor of Civil Engineering, Dept. of Construction Engineering and Management, Univ. Católica de Chile, Escuela de Ingeniería, Casilla 306, Correo 22, Santiago, Chile.
2. Instructor of Civil Engineering, Dept. of Construction Engineering and Management, Univ. Católica de Chile, Escuela de Ingeniería, Casilla 306, Correo 22, Santiago, Chile.