1. M.Eng.Sc. Student, Dept. of Civil Engineering, Faculty of Engineering Building, Univ. of Malaya, 50603 Kuala Lumpur, Malaysia.
2. Associate Professor, Dept. of Civil Engineering, Faculty of Engineering Building, Univ. of Malaya, 50603 Kuala Lumpur, Malaysia (corresponding author).
3. Associate Professor, Dept. of Civil Engineering, Faculty of Engineering Building, Univ. of Malaya, 50603 Kuala Lumpur, Malaysia.