Modeling, fragility and risk assessment of ancient freestanding columns and colonnades

A novel methodology for the fragility and risk assessment of ancient freestanding monolithic columns and colonnades is presented. The proposed approach is based on a modeling that can be implemented in a general purpose seismic design software, thus avoiding time-consuming and/or complicated simulations. Furthermore, a novel performance-based fragility and risk assessment framework, tailored to the problem at hand, is presented. The paper first discusses the problem of modeling these structures as rocking systems using negative-stiffness rotational springs. For the fragility assessment, pertinent performance criteria and intensity measures are proposed. The examples discussed show the capacity of the proposed modeling to simulate a variety of column and colonnade ancient structures and to quickly provide accurately the fragility curves within a fully performance-based framework.