Serviceability of stress ribbon bridges with external tendons

A prestressed concrete stress ribbon footbridge is a type of suspension bridge without towers. A conventional stress ribbon footbridge has two types of tendons in the concrete deck: the internal prestressing tendons (secondary tendons) and suspension tendons (primary tendons), which carry the dead load. This study targeted two footbridges with common structures that efficiently arrange the external tendons to reduce the construction cost and match the surrounding landscape. The Morino-Wakuwaku Bridge has the suspension tendons (primary tendons) in the concrete deck, and the prestressing tendons (secondary tendons) are placed outside of the deck as the external tendons. The Ohmaki-Dondo Bridge has external tendons (primary and secondary tendons) and bearings. These bridges differ in their structural and vibrational characteristics. Static loading tests using a vehicle, vibration tests using humans and finite-element method simulations were carried out to understand the characteristics of each bridge. This paper describes the structural and vibrational characteristics of prestressed concrete stress ribbon footbridges with external tendons and estimates their vibration serviceability performance for pedestrians based on the analysis and test results.