Structural investigations and strengthening of the civic tower in Vicenza

The paper presents the main aspects of the analysis of a slender brick masonry tower, located in the main square of Vicenza (Italy), next to the Palladian Basilica. It was subjected to several ordinary repairs during the centuries, but is currently suffering some structural damage, shown by an evident out-of-plumb and several patterns of vertical cracks on the masonry along its height. In situ investigations carried out on soil and foundations and at the base of the masonry walls allowed to detect the causes of the settlements. Along the height of the structure, extensive damage interests particularly the pillars of the belfry, where deterioration of the mortar, concentrated vertical cracks, and surface detachment of the bricks were detected. Further investigations on the pillars (sonic tests and tomography, corings) allowed assessing the consistency and the morphology of their inner structure. Repair and strengthening intervention have been performed at several levels (global stability, single materials or constructive systems). Strengthening interventions by repointing, also with insertion of small diameter steel bars (bed joint reinforcement), execution of injections and local rebuilding were performed on the masonry walls. In this phase, sonic tomography was extensively employed to evaluate the effectiveness of the intervention techniques. A 3D FE model calibrated on the experimental results allowed to assess the static condition of the whole structure and to analyze its safety in different load simulations for possible developments of further interventions.