Environmental and Life-Cycle Cost Evaluation of a Composite Timber-UHPFRC Bridge

Ultra-High-Performance Fibre Reinforced Cementitious Composite (UHPFRC) has recently been used to design lightweight structures and strengthen existing ones, with more than 300 applications in Switzerland. Several composite timber-UHPFRC bridges have been built in Switzerland, also to reduce the environmental impact of the construction. Girders are typically made of timber girders, while the deck slab is in UHPFRC. This high-performance material reduces, typically by 3, the deck weight compared to traditional reinforced-concrete slabs. Using UHPFRC also improves the durability of the timber elements as the UHPFRC deck slab remains crack-free under service conditions, meaning that the timber, located underneath the deck, remains dry and protected from direct water contact. This paper proposes a methodology to compare UHPFRC structures with traditional reinforced-concrete designs by evaluating the environmental impact and life-cycle costs over the expected bridge service duration. The first timber-UHPFRC bridge built in Switzerland is used as an example. Results show that composite structures can significantly reduce the environmental impact and costs of short-span bridge design. Timber-UHPFRC composite structures are thus promising to enhance the sustainability of the construction sector, especially in the infrastructure domain. Moreover, the methodology supports bridge owners in assessing the life-cycle costs and environmental impacts of structural designs involving UHPFRC with their associated maintenance scheme, leading to better decision-making.