Comparison of Form-finding Methods to Shape Concrete Shells for Curved Footbridges

Abstract

Shells are attractive and efficient structures that play a special role for engineers and architects. However, only few bridges supported by concrete shells have been designed and built after the Musmeci’s bridge in Potenza (Italy). Several numerical form-finding methods have been implemented in the last decades to optimize the shape of shells. In the present paper, a comparison of the Thrust Network Analysis (TNA) and Particle-Spring System (PS) is made by searching the optimal shape of a concrete shell supporting the curved cantilevered deck of a pedestrian bridge under the same boundary conditions. Finite Element Analysis was performed to compare the structural behaviour of the footbridges optimized by the two different form-finding techniques. The effectiveness of both form-finding methods in minimizing unfavourable tensile stresses in concrete shells, thus taking advantage of mechanical properties of concrete, is investigated. Furthermore, transverse deflections of the curved cantilevered deck were reduced introducing an external prestressing system applied to the upper flange of the ring box girder. Finally, the obtained results can help architecture and engineering practitioners to develop innovative bridge conceptual design.

Keywords:

• pedestrian bridge conceptual design
• shell footbridge
• shell form-finding
• thrust network analysis (TNA)
• particle-spring (PS) system
• concrete

Supplemental material

Supplemental data for this article can be accessed at https://doi.org/10.1080/10168664.2021.1878974

Additional information

Funding

The research was supported by the National Natural Science Foundation of China (Grant No. 51778148) and the FIR 2018 and 2019 fund of the University of Cagliari. Eleonora Congiu gratefully acknowledges Sardinian Regional Government for the financial support of her PhD scholarship attended at the University of Cagliari (P.O.R. Sardegna F.S.E. – Operational Programme of the Autonomous Region of Sardinia, European Social Fund 2014–2020 – Axis III Education and training, Thematic goal 10, Investment Priority 10ii), Specific goal 10.5.