The seismic response of a multi-drum stone colonnade

In this paper the response of a multi drum stone colonnade to horizontal forces is investigated by means of distinct elements and considering different models. In particular, the case study here presented concerns the main façade of the Parthenon, representative of the Greek temple typologies, that is composed by columns made with large drums, architrave arranged in simple support and a triangular tympanum on top. Analyses were conducted using UDEC 2D software: the colonnade has been described by a 2D model in order to exclude the risk of torsional responses. Each element of the single column has been modeled as a rigid block, and the interaction between the blocks has been represented using an interface of zero thickness, which was characterized by an elastic stiffness, a tangential stiffness, a cohesion stress and a friction angle. Pushover analyzes were conducted on three different models that represent different degrees of connection between the drums: MOD1 that assumes simple support contacts between the blocks; MOD2 that introduces the connectors between the blocks of the columns; MOD3 that adds to MOD2 the connectors between columns and architrave. The results of the analyses are shown in terms of capacity curves and demonstrate a significant increase in the ultimate displacement capacity passing from MOD1 (absence of connections) to MOD3 (column-architrave connections) with the same horizontal collapse load. The results are also discussed with the aim of defining rules for the seismic vulnerability mitigation of these structures.