This work presents an extensive static and seismic retrofitting intervention performed on a relevant historic case-study building, the Venetian sawmill of Vallaro (Brescia, Italy). This heritage construction from the end of the 19^th century features three building portions, two realized in timber and one consisting of a masonry structure with timber floors and roofs. The building had been neglected for decades and was in a poor state of conservation, despite representing a valuable example of the typical historic architectures of the mountainy area in the Province of Brescia. With the support of the local municipality, a complete restoration of the sawmill has started, with the objective of transforming it into a territorial museum. To this end, a series of reversible and compatible timber-based interventions were planned in consultation with the local superintendence for architectural heritage. The structural design aimed at preserving the historic value of the sawmill, especially in its original timber components, such as trusses, braced columns, and diaphragms. The present case study enables to showcase the advantages of the applied strengthening methods in such a complex architectural restoration and the importance of tailored structural detailing, combining the improvement in static and seismic performance with the protection and preservation of ancient timber members.

Reversible retrofitting techniques for protecting existing or historical buildings against seismic events have found increasing application in the recent years. In particular, the use of wood-based strengthening solutions for both timber and masonry structures has shown promising results in terms of reversibility, compatibility, lightness, sustainability, and effectiveness. With reference to existing timber floors, an excellent method to enhance their seismic response is the fastening of an overlay of plywood panels to the existing sheathing, an intervention that greatly improves in-plane strength, stiffness, and energy dissipation. In order to promote the use of this retrofitting method in practice, calculation tools supporting the design and modelling of timber diaphragms strengthened with plywood panels, have been developed. As a result of a fruitful synergy between academic research and professional engineering, this work presents relevant recent examples of application of the developed calculation tools in the seismic retrofitting of timber diaphragms in existing buildings. Three significant case-study buildings are examined: two masonry churches with monumental timber roofs, and an ancient sawmill with a mixed timber-masonry structure, all located in the province of Brescia (Italy). The developed tools allowed to conduct parametric analyses to calibrate the best retrofitting strategy, and to analyse the additional benefits of the plywood-based retrofitting interventions, especially in terms of hysteretic energy dissipation, affordability, and cost- and execution-effectiveness. This work can contribute to the promotion of timber-based techniques in the combined structural, seismic, and conservation upgrading of existing buildings belonging to the architectural heritage of seismic-prone countries.

This work presents the application of timber-based retrofitting techniques to a case-study stone masonry church featuring a wooden roof from 18^th century. From the static point of view, the original roof structure presented a number of undersized structural elements, and its members were poorly or not connected among each other and to the masonry, making the church vulnerable to seismic loads as well. Thus, the roof was retrofitted with wood-based techniques, including an overlay of plywood panels, against seismic actions. These affordable, rapid, easily realizable interventions enabled both the conservation and seismic retrofitting of the roof, providing an adequate load-carrying capacity for static loads, and an effective diaphragm action against seismic loads. The conducted numerical analyses showed that the realized interventions greatly improve the seismic behaviour of the building. Besides, when the additional energy dissipation provided by the plywood panels overlay is taken into account in the numerical model, the church would even potentially be able to fully withstand the expected seismic action of the site.

Wood-based retrofitting techniques for seismic upgrading and architectural conservation of existing buildings have found increasing application in the last decades. With reference to the in-plane seismic strengthening of existing timber floors, a particularly efficient solution consists of an overlay of plywood panels fastened to the sheathing. This technique allows a great improvement in strength, stiffness, and energy dissipation of the floors. Yet, when adopting this strengthening solution for existing floors in highly seismic regions, the target design loads could require large values of in-plane strength and stiffness for the retrofitted diaphragms, and this could cause their beneficial, dissipative potential to be reduced. Thus, in this work, a strengthening solution is presented, able to retrieve high strength and at the same time activate large energy dissipation in the floors. The proposed technique consists of the creation of two independent shear planes by means of two different superimposed overlays of plywood panels. Previously developed analytical and numerical models describing the in-plane response of floors retrofitted with a single plywood overlay were adapted for the present case with two overlays, validating the results against an experimental test conducted on a sample representing a floor portion. Very good agreement was obtained between experimental and analytical as well as numerical results, thus the proposed approaches enable an efficient design process and an accurate simulation of the proposed retrofitting technique.