In-plane seismic response of a fastening system for horizontal concrete cladding panels in RC prefabricated buildings

This paper presents experimental and analytical investigation of the fastening system typically used for horizontal cladding panels in RC precast industrial buildings in Central Europe.The considered system consists of two main parts: a pair of top bolted connections, which provide the horizontal stability of the panel, and a pair of bottom cantilever connections, which support the weight of the panel.Based on experimental tests, the in-plane response mechanism of the fastening system was identified.It consists of three distinct stages: sliding with limited friction, contact with the panel causing an increase in stiffness of the connection, and the failure.In the sliding phase, there are only very small friction forces between elements.Significant relative displacements of a couple of centimetres can occur between the panel and the column.After the contact of the connection element with the panel, there is a significant increase of forces, which is followed by a practically brittle failure of the connections.It has been found that the capacity of the complete system is limited by the displacement capacity of the top connections, which are the weakest components.Non-linear numerical models for dynamic analysis were formulated in the OpenSees framework.The typical Coulomb friction model was used to describe the friction in the top connection, whereas the response of the bottom connection during the sliding phase was better simulated with viscous friction model.The contacts that occur when the gaps in connections are depleted were simulated by an instant increase of the connection's stiffness.The numerical models were validated by the tests in cyclic static and in fully dynamic conditions.The results show a reasonably good match between experimental and numerical response.