A simple and effective rigid beam model for studying the dynamic behaviour of freestanding columns

In this work, a simple and effective Rigid Beam Model is proposed for studying the dynamic behaviour of ancient freestanding stone columns. As well known, monolithic and multi-drum freestanding columns are historical structural elements typical of ancient temples that still can be found in the Mediterranean area. These columns are particularly prone to collapse in case of seismic actions. The dynamic behaviour of freestanding columns has been studied by many authors in the past [1-3], and it is characterized by a strong nonlinearity due to sliding and rocking between the drums. The Rigid Beam Model here described assumes each drum of the column as a rigid beam element and each interface between the drums as a node of the model able to move horizontally. Similar to Housner [1] approach, this model assumes small displacements and no sliding between blocks. Furthermore, the material nonlinearity is considered by means of a moment-rotation constitutive law slightly modified with respect to the bilinear one introduced by Housner. Numerical simulations were performed on monolithic and multi-drum columns modelled using the proposed Rigid Beam Model approach. Results are compared against simulations of the same columns undertaken by means of the Discrete Element Model, which is able to consider large displacements and the possible sliding between the drums, and it has already proven its effectiveness in simulating column behaviour [2-4]