First of all, it is needed to define the frictional properties of the materials constituting the friction pad of the dampers to be located in the connections. This part of the project is aimed at the identification of the best material as a compromise between two needs which are fundamental for the use of friction materials in structural applications for seismic design. Such needs are, on one hand, the attainment of a friction coefficient as high as possible and, on the other hand, the use of a friction material whose consumption is as low as possible.
In addition, it is necessary to evaluate the slip-force behaviour under cyclic actions, such those occurring during seismic events, carrying out a wide experimental activity on different types of materials under different loading conditions. To this purpose, a universal testing machine will be used to apply cyclic loadings to single bolt or multiple bolts specimens (Fig. 2). In addition, a specific impulsive machine will be used to perform impact tests which are needed to obtain the basic information for the investigation of the robustness of the new connection typologies under exceptional loading conditions, such as blast loading, impact loading, etc.
At the end of this work package, only two materials will be selected for the successive experimental tests to be carried out on full-scale connections. As main result of this work package, within the framework of the component approach, currently codified in Eurocode 3 part 1-8 for predicting the joint behaviour, a new joint component, namely “friction damper pre-stressed with high strength bolts”, will be completely characterized.
Tests on friction dampers