1. Associate Professor, Department of Civil Engineering, Federal University of Rio Grande do Sul, Brazil, Telephone: + 55 51 81239266, Telefax: + 55 51 33083999, E-mail: consoli@ufrgs.br
2. Research Assistant, Department of Civil Engineering, Federal University of Rio Grande do Sul, Brazil. Telephone: + 55 51 33083552, Telefax: + 55 51 33083999, E-mail: rr_moraes_14@hotmail.com
3. PhD Student, Department of Civil Engineering, Federal University of Rio Grande do Sul, Brazil, Telephone: + 55 51 33083669, Telefax: + 55 51 33083999, E-mail: lufega@yahoo.com.br