1. Associate Professor, Dept. of Civil Engineering, Federal Univ. of Rio Grande do Sul, Av. Osvaldo Aranha, 99, 3. andar, 90035-190, Porto Alegre, Rio Grande do Sul, Brazil.
2. Research Assistant, Dept. of Civil Engineering, Federal Univ. of Rio Grande do Sul, Av. Osvaldo Aranha, 99, 3. andar, 90035-190, Porto Alegre, Rio Grande do Sul, Brazil.
3. Associate Professor, School of Engineering and Architecture, Catholic Univ. of Pelotas, Rua Félix da Cunha, 412, 96010-000, Pelotas, Rio Grande do Sul, Brazil.