Abstract

Cable-stayed bridges and extradosed bridges are thought to be similar kinds of structures because 

both bridges use stay cables for reinforcement. However, the safety factors of stay cables of both 

bridge types are stipulated differently in many international standards i.e. Japanese specifications 

suggest the safety factors of 2.5 and 1.67 for the design of cable-stayed bridges and extradosed 

bridges respectively. In this paper, an analytical study is carried out for the investigation of the safety 

level of stay cables of both bridge types at fatigue and ultimate limit states. Subsequently, the Mean 

Value First Order Second Moment (MVFOSM) reliability method is also performed for the 

verification of safety factors of stay cables. Finally, it is found that the safety factors of stay cables 

in the range of 2.3 to 2.5 and 1.67 are essential to satisfy the fatigue and ultimate limit states and 

target reliability index of 4.0 of cable-stayed bridges and extradosed bridges respectively.

Keyworkds: cable-stayed bridge; extradosed bridge; stay cable; safety factor; reliability.