Vertical Connectors in Ancient Monuments: Documentation and Experimental Study of the Behaviour of Iron and Titanium Connectors

Ancient monuments are constructed following the dry construction system. Large dimensional structural members, with perfectly plane interfaces, are placed without mortar. Two types of iron connectors, vertical and horizontal, used to connect individual stone blocks, are activated in case of relative displacements, e.g. earthquakes. The paper focuses on, iron or titanium, vertical connectors, crossing the interfaces between successive stone courses, and investigates their seismic behaviour. In situ and bibliographical documentation of vertical connections in ancient Greek monuments, including their topology, dimensions, and typical pathology attributed to them, served as a basis for the design of an experimental program. First, specimens simulating the original connections are tested under monotonic and cyclic actions. The behaviour of those connections, effectuated using iron vertical connectors, having confirmed the pathology observed in situ, i.e. fracture of the substrate, an alternative connection was tested aiming at avoiding or significantly delaying the failure of the substrate (marble). An unbonded length was provided to the connector, close to the interface, to postpone the contact between the connector and the marble. The test results confirmed the anticipated change of behaviour, associated though with smaller shear resistance and larger displacements at its attainment than for the original connections.