1. Dipartimento di Ingegneria Civile, Edile-Architettura e Ambientale, Università degli studi dell’Aquila, L’Aquila, Italy; International Center for Mathematics and Mechanics of Complex Systems, Università degli studi dell’Aquila, L’Aquila, Italy
2. Department of Mechanical Engineering, University of California, Berkeley, CA, USA; International Center for Mathematics and Mechanics of Complex Systems, Università degli studi dell’Aquila, L’Aquila, Italy