Experimental stress analysis of historical forged tie beams of archaeological museum of Spina in Ferrara, Italy

In historical (ancient) buildings, tie beams may be broken by corrosion and, in this case, knowledge of the axial forces in the remaining tie-beams is very useful to select the tensile force the substitute tie beam is to be given. In the case reported hereafter, a tie-beam of a pavilion vault arcade facing the inner garden of Ludovico il Moro Palace (presently Museo di Spina) in Ferrara suddenly broke apart and it was then necessary to substitute the old tie-beam and to verify the resulting homogeneity of the anchoring tensile forces along the arcade. Mechanical and metallurgical analyses of the old tie beam were performed to evaluate possible heterogeneities and to yield a reliable Young modulus. Vibration tests were adopted to evaluate the tensile forces of the substitute and of the old tie beams as well, and the obtained stress states were confirmed by using the Barkhausen method (magnetostriction technique)