HISTORY OF A FAULTY RETROFITTING: THE S. SEBASTIAN BRIDGE IN LOANO (ITALY)

Masonry bridges are well inside the European monumental heritage; even though protected by the Preservation Authorities, their retrofitting does not always follow rational approaches. In this paper, the case study of the S. Sebastian Bridge in Loano (Italy), a pedestrian bridge dating back to 1691, is discussed. The collapse of the aedicule, and the subsequent collapse of the armilla, are found to be the result of several causes: i) poor and non-rational original design; ii) degradation of poor materials due to environmental actions; iii) wind-induced fatigue collapse of some material; iv) thermal stresses due to the dilatation of a modern concrete pavement. The retrofitting criteria proposed for this case are discussed comparing their effectiveness and the conservation of the monumental value of the bridge.