1. Ph.D. Candidate, Dept. of Construction Management, School of Civil Engineering, Tsinghua Univ., Beijing 100084, China.
2. Associate Professor, Dept. of Construction Management, School of Civil Engineering, Tsinghua Univ., Beijing 100084, China (corresponding author).
3. Professor, Dept. of Construction Management, School of Civil Engineering, Tsinghua Univ., Beijing 100084, China.