PSI - Issue 79

Aikaterini Marinelli et al. / Procedia Structural Integrity 79 (2026) 182–189

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Data collection proved particularly demanding, especially regarding the structural geometry, material properties, and environmental conditions specific to the area. Valuable sources of information had been the original design drawings in Stevenson’s Account (Stevenson, 1824), historical wind data from the MET office (the UK's national weather service) archive and current stations, and wave-monitoring buoys in the North Sea (CEFAS, 2025). Standards and well-established methods in the literature were followed to derive wind and wave loading, which together with the dead loads supplied by NLB, formed the load combinations for a range of scenarios tested.

Fig. 2. Methodological steps for the structural assessment of the Bell Rock lighthouse by numerical modelling

The wind loading on the structure was calculated using BS EN 1991-1-4:2005+A1:2010 and the associated National Annex, with a basic wind velocity at 25.9m/sec. Uniform wind loading corresponding to the upper courses of the lighthouse was conservatively determined to be applied as a pressure on the windward surface (2kN/m 2 from the East). The Scottish Environment Protection Agency (SEPA) oversee the buoy nearest to the lighthouse on the coastal side. There is historic evidence that a wave height of 18m was recorded in March 1984. This height is compatible with the claim of waves having reached 21m in the past, and a wave impacting the lighthouse whilst keepers are in one of the rooms, with the lowest being approximately 15m up the tower (Stevenson, 1824). The Centre for Environment, Fisheries and Aquaculture Science (CEFAS) determined the significant wave height (H) as 10m, with a period (T) at 7.5sec. By application of the BS 6349-1-2 and the theory of Wienke and Oumeraci (Wienke and Oumeraci, 2005), the total wave load was calculated at 6128kN for a 10m high wave, breaking at a height of 14.5m, a value that is comparable with findings in relevant literature (Trinh et al., 2016). A simplified uniform pressure approach is implemented for the application of wave loading to an impact area, due to the lack of visual footage of waves breaking on the lighthouse or any on-site measurements that would justify more accurate wave force spatial distribution options (Antonini et al., 2019, Pappas et al., 2019, Raby et al., 2019). 3. Numerical Investigation The numerical modelling and analysis of masonry structures present significant challenges due to their complex material behaviour and structural heterogeneity (Theodossopoulos and Sinha, 2013, Roca et al., 2010). The inherent presence of joints, which serve as primary sources of weakness, discontinuity and nonlinearity, combined with uncertainties in material properties and geometrical configurations, significantly complicates the numerical modelling of masonry structures. Various modelling approaches proposed in the literature exhibit a range of advantages and limitations, reflecting the complexity of accurately capturing masonry behaviour (Asteris et al., 2016). To achieve a balance between computational efficiency and modelling accuracy suited to the objectives of this study, a macro-modelling approach was adopted using the finite element method within the ABAQUS simulation environment. In this framework, masonry is represented as a homogenised continuum, implicitly accounting for the influence of any joints and adopting material properties being an adaptation of literature values to historic data of local quarries (Fig. 3a).