Influence of cladding panels on the first period of one-story precast buildings

During the recent severe seismic events, as L'Aquila (2009) and Emilia earthquakes (2012), the collapse of cladding panels system in precast buildings has been frequently observed due to their connection system failure. Such a damage have demonstrated the deficiency of the actual design approach, that considers cladding panels as non-structural elements, neglecting any interaction with the structure under bi-directional and dynamic seismic excitations. This paper investigates the influence of vertical cladding panels on the first vibration period of one-story precast concrete buildings, with floor rigid in its own plane. At this purpose, a bare structural elastic model and an innovative elastic model of the building with cladding system are implemented and a parametric study is performed. The results of the parametric study show a high influence of the panels on the first period of the analyzed buildings, as well as the inadequacy for this typology of buildings of the simplified relationship for computing the fundamental period proposed by some codes. More suitable formulas are proposed to evaluate the first period in a linear static analysis of one-story precast buildings, both in the case of bare buildings and of buildings with cladding system.