Automatic CAD kinematic limit analysis approach for the limit analysis of masonry towers

In this paper, a simple and fast 3D CAD approach to estimate the seismic vulnerability of existing masonry toweers is presented The procedure consists in a 3D detailed geometnc model of the tower made in CAD, where the structure is obtained by means of the assemblage of different 3D volumes having complex shape. The choice of the different volumes is not only related to the need of distinguishing between different matenals/weights/loads, but is primarily made to identify specific failure mechamsms activating at the interfaces between contiguous volumes. The collapse acceleration isthenautomatically evaluated applying the kinematic theorem oflimitanalysisfornotensionmatenalsonmepre-assigned failure mechanism chosen in the pre-procession phase. Some few mechamsms are tested in the paper, considering L s e occurring most frequently in past seismic events, as for instance vertical splitting, simple overturning at the base, rocking with inclined yield lines and combined rocking and vertical splitting. The inclusion of different mechamsms is very straightforward, simply requmng an updating of the number and shape of the volumes directly in the CAD software by means of the cutting plane command The mechanism associated to the minimum acceleration, in agreement with the kinematic theorem of limit analysis, is that activating most probably in reality during a seismic event The automatized procedure is fast and straightforward, being applicable also by all those technicians not familiar with Limit Analysis concepts. Two examples of technical relevance on two historical masonry towers in Italy are discussed to show the capabilities of the approach