ABSTRACT
In some Chinese codes, automobile load and train load are directly superimposed in the design of bridges carrying both road traffic and rail traffic. It is a bit conservative to neglect the multiple presence factor (MPF) for two live loads. To quantify multiple presence factor of road-rail bridges, the random traffic flows of road and rail vehicles are established by the Monte-Carlo method. The internal forces of the control sections are calculated for simply supported bridges of different spans. Probability analysis of the data is conducted to obtain the multiple presence factors for multi-lane automobile load, multi-lane train load, and multi-lane automobile-train load. It is found that the multiple presence factors of pure automobile load and train load agree well with the current codes. The multiple presence factor of both automobile and train loads is finally proposed.
