1. Professor, Mechanics Division, Dept. of Mathematics, Univ. of Oslo, Blindern, NO-0316 Oslo, Norway; and Univ. Européenne de Bretagne, Univ. de Bretagne Sud, LIMATB–Laboratoire d’Ingénierie des Matériaux de Bretagne, UBS–Lorient, Centre de Recherche, 56321 Lorient Cedex, France (corresponding author).
2. Professor, Dept. of Civil, Environmental and Natural Resources Engineering, Division of Structural and Construction Engineering–Timber Structures, Luleå Univ. of Technology, SE-97187 Luleå, Sweden.