Scaling in structural brittleness: next revolution in bridge engineering?

Based on the scientific and technological revolutions that have characterised Structural Engineering during the last two centuries, we can acknowledge how the historical scale doubling of suspension bridges has occurred for at least four times, from the beginning of the nineteenth to the end of the twentieth century. These four revolutions represent mankind’s tangible challenge against natural forces: gravity, wind, and earthquake. In this context, the prospective scale doubling that will be requested by next-generation bridges (e.g. the Messina Strait Bridge) could take place only if significant scientific and/or technological innovations occur. This opportunity is presently offered by Fracture Mechanics, since any appropriate advanced design approach should also take into account brittleness size-scale effects, in addition to loading-capacity size-scale effects, which are well-known since Galileo’s studies. From the technological point of view, the open problem of physical similitude could be effectively solved by using fibre reinforcement.