A proposal for the multi-risk assessment of small span bridges: the six-simple method

The evaluation of bridge safety conditions is essential for a proper management of infrastructure networks. During the last year a great effort has been made by the scientific community for medium to long span bridges, whereas few studies are available for the case of small span bridges. For the latter cases, indeed, the application of the conventional methods could lead to overly burdensome procedures or even to misleading results. This study proposes a multi-risk assessment method for small bridges with span under 6 m. The method, called “six-simple” and inspired by the existing Italian 2022 Guidelines, is based on the evaluation of attention classes and consider four risk sources: structural and foundational, seismic, landslide, and hydraulic. Compared to existing methods, six-simple is designed to maintain high assessment standards while reducing the number of required parameters and the time needed for the application. Sensitivity analyses are performed to catch key parameters influencing the classification, and statistical analysis are developed to describe the overall trend of the method. The paper closes with the application of the six-simple method to 15 small bridges.