The role played by inclination in both the load carrying capacity and seismic assessment of masonry bell towers is investigated through the results obtained from different analyses on three case studies. The Italian Code for the built heritage is not explicit about the influence of inclination on the seismic assessment of towers, leaving to practitioners the task to properly consider it, potentially leading to both an overestimation of the capacity and an underestimation of the horizontal actions. The case studies investigated in this paper are three leaning masonry bell towers, all exhibiting a quite meaningful inclination and all located in Emilia-Romagna region (Italy), recently (2012) stricken by a moderate/high intensity seismic sequence. This study compares the procedure provided by the Italian Code with the finite element (FE) results obtained through non-linear static analyses and proposes a modification of the Italian code simplified mechanical model (SMM), which explicitly accounts for the actual inclination of the towers within a cantilever beam approach. The FE results show that inclination may considerably reduce the load carrying capacity, increasing the seismic vulnerability of the structures. The SMM approach proposed properly takes into account the role played by inclination, always providing results on the safe side with respect to FEM

No abstract

No abstract

No abstract

Seismic assessment is a paramount issue and a valuable instrument towards the conservation of vulnerable structures in seismic prone regions. The past seismic events have highlighted the vulnerability of masonry towers that is exhibited by severe structural and nonstructural damages or even collapses. The preservation of existing structures, mainly focused on the built heritage, is emerging and imposing substantial enhancements of numerical methods, including pushover analysis approaches. The accuracy of the estimated seismic capacity for these structures is correlated with the assumed strategies and approximations made during the numerical modeling. The present paper concerns those aspects by exploring the limitations and possibilities of conceiving pushover analysis in the finite element method environment. The most crucial target is tracing in a pushover capacity curve the corresponding initiation of structural damages, maximum load-bearing capacity, and the ultimate displacement capacity. Different recommendations for achieving this target have been proposed and illustrated for practical utilization. Three representative geometrical towers, adopting three different materials and five different load patterns, are investigated in this study. The load pattern’s role and necessity of the displacement-like control approach for the pushover analysis are exploited. This paper highlights the load-bearing capacity overestimation when the force-controlled are implemented. The material model influences the achievement of softening branch with a distinguishable displacement capacity.