Deterministic and reliability analysis of prestressed concrete bridge girders: comparison of the Chinese, Hong Kong and AASHTO LRFD Codes

This paper compares the prestressing requirements and reliability indices of prestressed concrete bridge girders designed using three codes: the Chinese Code, the Hong Kong Code and the AASHTO LRFD Code. Typical post-tensioned concrete girders of spans ranging from 25 to 40 m are considered. Deterministic analysis indicates that the service limit state governs the design according to the Chinese Code and the AASHTO LRFD Code. However for the Hong Kong Code, only those with longer spans are controlled by the service limit state. The actual number of strands needed by the AASHTO LRFD Code is quite close to that needed by the Chinese Code, while that required by the Hong Kong Code is about 18-33% higher than that required by the AASHTO LRFD Code. Disparity between reliability indices for flexural capacity based on the requirements of the service and strength limit states exists in all three codes. However, the disparity does not follow the same trends as that of the required number of strands for service and strength limit states in the three codes. In addition, the reliability index for flexural capacity according to the requirements of the service limit state is always higher than that of the strength limit state in the three codes. The actual reliability indices for flexural capacity of the girders considered according to the three codes, which are governed by the service limit state, are close to one another.