Application of timber-based techniques for seismic retrofit and architectural restoration of a wooden roof in a stone masonry church

Recent seismic events in Italy highlighted several vulnerabilities in historical buildings belonging to the national architectural heritage. Among others, monumental constructions such as churches appeared to be prone to local (out-of-plane) collapses of masonry walls, often caused by the presence of poor-quality materials and inadequate connections among structural elements. Seismic retrofitting methods are thus necessary, but should also be reversible, not invasive, and aimed to the architectural conservation of the construction, preserving its historical value. In this framework, the potential of timber-based techniques as reversible and effective methods for seismic strengthening and restoration of buildings is promising. This work presents the case study of St. Andrew's Church in Ceto (Brescia, Italy), a stone-masonry monumental building featuring a timber roof from 18th century. Following several inspections commissioned by the curia of Brescia, the church was found in fair structural conditions, with the exception of the wooden roof, having structural elements poorly or not connected among each other and to the masonry. To reduce the evident seismic vulnerability of the church, the roof was retrofitted with plywood panels, allowing for an affordable, rapid, and easily realizable intervention. In this way, the original timber structure could be preserved, creating an adequate load-carrying capacity for static loads, as well as an effective diaphragm against seismic loads. The conducted calculations and numerical analyses showed that the realized intervention greatly improves the seismic behaviour of the building, demonstrating the benefits of wood-based retrofitting and supporting their use for the preservation of architectural heritage.