1. Ph.D. Candidate, Dept. of Construction Management, Tsinghua Univ., Beijing 100084, China.
2. Assistant Professor, School of Building Construction, Georgia Institute of Technology, 280 Ferst Dr., Atlanta, GA 30308.
3. Lecturer, School of Management Science and Engineering, Central Univ. of Finance and Economics, Beijing 100081, China (corresponding author).
4. Professor, Dept. of Construction Management, Tsinghua Univ., Beijing 100084, China.