Parameters governing the response of under-deck cable-stayed bridges

In the past quarter century, a number of bridges have been built that do not fit into the conventional types of cable-stayed bridges. These are under-deck cable-stayed bridges and combined cable-stayed bridges. In this paper we define the first of these two types and set out its mechanisms of response. We then establish and analyze the parameters that determine the permanent response and the response to live load of these bridges. Lastly, we draw conclusions relating to their behaviour and define design criteria for them with the aim of making cable-staying systems highly efficient and allowing the design of much lighter and slimmer structures.