1. Assistant Professor, Dept. of Structural and Geotechnical Engineering, Polytechnic School at Univ. of São Paulo, 05508-070 São Paulo, Brazil (corresponding author).
2. Full Professor, Dept. of Structural and Geotechnical Engineering, Polytechnic School at Univ. of São Paulo, 05508-070 São Paulo, Brazil.
3. Associate Professor, Dept. of Mechanical Engineering, Polytechnic School at Univ. of São Paulo, 05508-030 São Paulo, Brazil.