Influence of the geometric model on the structural analysis of architectural heritage

Abstract

Geometric models employed for structural analyses are usually strongly simplified, in order to make easier and faster the numerical solving. Sometimes this approach is valid and convenient as far as it does not influence the analysis results. However, depending on the circumstances and the objectives of the analysis, the model has to be accurately and precisely represented to capture the necessary outputs. This is the case with architectural heritage. In fact, in this field, the surveyed objects are often characterised by complex forms and remarkable damages, which can affect the geometry significantly. Nowadays, many techniques are available to obtain very detailed models of the surface of the object, but they do not allow to consider also interior damages or the constructive features. This information can be obtained through a careful knowledge and anamnesis of the object to study, based on visual inspection and instrumental measures. In this way, the creation of the model to undergoes to a structural analysis, consists in a synthetic operation conducted by the operator in a conscious way. This paper aims to prove that the results of a structural analyses can change significantly, depending on the accuracy and the level of detail of the model. The study was conducted on a basic building element, that is a column, really existing and belonging to a monumental fountain. The column was modelled in five different ways which differ in the level of detail. An ultrasonic test was conducted on the real object to characterise cracks which were taken into account in the most accurate models. A comparison among the five models was done from a static and dynamic perspective, through the following analyses: static, buckling, modal and dynamic with response spectrum.