Reliability Assessment of Multi-Span Masonry Arch Bridges Considering Geometrical Uncertainties

Historical masonry arch bridges (MABs) are more than structural assets; they embody cultural identity, architectural heritage, and the construction knowledge of past generations. In Portugal, many metallic bridges were replaced by MABs, which today form an essential part of the national railway network. Due to their age and the cumulative effects of degradation, these structures are particularly vulnerable to both natural and anthropogenic hazards. The occurrence of such events may lead to disruptions in functionality, with significant consequences for mobility and infrastructure resilience. This study focuses on the structural assessment of MABs in Portugal, explicitly accounting for geometrical uncertainties associated with this bridge typology. The analysis is conducted using the LUSAS finite element analysis software package in combination with Grasshopper, which enables parameterization of the bridge geometry and its integration into a stochastic assessment framework. The reliability index is employed as the key performance indicator to evaluate structural performance. The proposed approach is demonstrated through an application based on the empirical design rules of a historical masonry arch bridge located in Portugal. The results highlight the influence of geometrical uncertainties on the reliability index and demonstrate the potential of the proposed framework to support decision-makers in the preservation and management of historical bridge assets.

Keywords: Surrogate models, Heritage structures, Finite element method, Out-of-plane seismic capacity, Modal pushover analysis.