Sound Conceptual Design for Sustainability in Bridges

How did the great bridge designers of the past leave behind such wonderful structures in an age before computers and thick standards? This has been the author's question for many years. It was known that the three elements of Roman beauty also applied to bridges. But that alone is not a sufficient explanation. And when the world set sustainability as a new goal, it turned out that it could be successfully explained by introducing the idea of structural sustainability. This paper explains the conceptual design of Japanese bridges in terms of structural elegance and structural sustainability.