Brick masonry staircases of the early 20th century: historical research, condition assessment and diagnostic investigation of a “transition” construction type

Staircases play a key role in the rehabilitation and retrofitting of historic public buildings in terms of respecting building regulations for fire protection, accessibility and seismic resistance. Assessing their construction materials and techniques, as well as their current condition and residual performances, are paramount in order to employ effective, compatible and low-intrusive conservation measures. In particular, staircases dating back to the early 20th century call for a comprehensive understanding of technical and technological solutions. This is because they were conceived in a “transition” phase from traditional masonry structures to modern systems based on the employment of metal elements. Thus, they show a variety of hybrid solutions, often depending on the local practice and the specific application. Consequently, historical research from technical handbooks of the time should help define the purposes and boundaries of the diagnostic investigation of characteristics and pathologies. Additionally, both documentary records and on-site/laboratory tests should support the identification of potential local failures, which are generally omitted in global analytic simulations. In the light of the above-mentioned issues, the paper provides an overview of the historical evolution of masonry staircases of the early 20th century, with a specific focus on brick structures in central-southern Italy. Based on the most documented systems and the most recurring pathologies, this research outlines a methodological framework for on-site and laboratory diagnostic investigation, aimed at the identification of construction materials and techniques, detection of decay patterns and characterisation of mechanical performance. The proposed framework is applied to a case study, the monumental staircase of a school building, and some insights into the operational procedures are also addressed.