1. School of Civil and Environmental Engineering, The University of New South Wales, Sydney 2052, NSW, Australia e-mail:
2. Department of Architecture and Territory (dArTe), Inter-University Centre of Theoretical and Experimental Dynamics, University “Mediterranea” of Reggio Calabria, Reggio Calabria 89124, Italy e-mail:
3. School of Mathematics and Statistics, The University of New South Wales, Sydney 2052, NSW, Australia e-mail: