A site-specific traffic load model for long-span multi-pylon cable-stayed bridges

This paper proposes a site-specific traffic load model for long-span multi-pylon cable-stayed bridge. Structural effects are primarily investigated based on influence lines, which are identified as either global effect (GE) or partial effect (PE) depending on the effective influenced region. GEs are further categorised as sensitive effect (SE), insensitive effect (ISE) or less sensitive effect (LSE), considering sensitivity to unbalanced traffic loading. Three on-bridge traffic states are simulated, and Weibull extrapolations are utilised to predict the extreme responses. These responses are analysed and compared with several design codes. Results indicate the maximum response is only 75% of the value calculated based on the design code of China (D60), and even lower than other codes. The responses show strong positive correlation with traffic parameters of annual average daily traffic volume and heavy vehicle proportion, and the on-bridge traffic states have significant influence on the responses. Further, the identified effects of ISE, SE and LSE present different responses, which indicate specific load models are needed accordingly. Finally, a site-specific traffic load model consisting of load form, loading pattern, multi-lane factor and load value is recommended, which gives an accurate illustration on the structural effects and traffic responses.