engleski

Reconstruction of the Rector's palace atrium in Dubrovnik : the key role of the column connections

The Rector’ s Palace is one of the most valuable heritage buildings in the historic Old town of Dubrovnik and the world famous setting for concerts and exhibitions. The Palace Atrium is surrounded by two stories structure comprising quadripartite masonry vaults supported by masonry walls and stone columns. Historically, this structure has suffered numerous collapses and damages and restorations were frequently made. Despite this, many distinct fractures are concentrated around the traditionally made column connections with capitals and bases. Carefully smoothed stone contact areas are joined with iron dowel, which is centrally placed in a slightly larger hole, with a lead infill. These contacts do not have sufficient rotational stiffness and the ability to transmit eccentric loads. Therefore, high edge stresses and fractures at connections are unavoidable. With time, the small rotational stiffness of joints becomes even smaller and the behaviour is approaching one of the hinge joint. This effect may endanger the global stability of this structure, as only three aligned hinges are sufficient to render the system unstable, i.e. the system is “ almost” statically determinate and has only a small reserve in bearing capacity. Various retrofit strategies for column connections can cause considerably different stress distribution and by ignoring or underrating these effects, the safety factor can be seriously overestimated. This paper confirms the above assertions using a range of computational models: from simple frame and shell models to complex 3D solid models. This work also points out the significance of connections in historical buildings and attempts to investigate possible retrofit concepts. Numerous retrofit solutions were considered and results show a significant influence of this small detail of the bearing system on the global behaviour and stability of structure.

historic stone masonry, columns connections, dowel, contact stress

Članak je izabran u posebno izdanje knjige vezane za projektiranje i ocjenu tehnika ojačanja povijesnih građevina, a prvotno je objavljen na konferenciji: 11th International Conference on Structural Repairs and Maintenance of Heritage Architecture, STREMAH 2009