Cable-stayed bridge concept for longer spans

Achieving larger maximum spans by inventing new bridge systems has always been a fascinating intellectual challenge. Several concepts of modified cable-supported bridges have been proposed in the past that promise to surpass the more traditional cable-supported bridges in terms of maximum span length. Some of these concepts are recalled in this paper. An alternative concept derived from the classical cable-stayed bridge system is presented. Instead of vertical pylons, pairs of inclined pylon legs, spreading out longitudinally and connected at the top by horizontal ties, are used. The merits and shortcomings of such a system are discussed. Based on a comparative analysis of forces, quantities, and costs, it is concluded that the alternative concept presented in this paper not only allows the achievement of larger maximum spans, but also can lead to an economically advantageous design - even within the span-length range of the classical cable-stayed bridge system.