Past seismic events, including L’Aquila earthquake in 2009 and Emilia earthquake in 2012, clearly demonstrated the inadequacy of the current design approach for the connection system of the cladding wall panels of precast buildings. To clarify this problem, the present paper investigates the seismic behaviour of a traditional precast structural frame system for industrial buildings with different type of connections of its cladding wall panels. This system consists of a statically determined pendulum arrangement of panels, each supported with two hinges to the structure, one at the top and one at the bottom, so to have under seismic action a pure frame behaviour where the wall panels are masses without stiffness. Adding mutual connections between the panels, the wall cladding system becomes part of the resisting structure, leading to a dual frame/wall system or to a wall system depending on the stiffness of the connections. The results of a parametric investigation based on non-linear static and dynamic analyses show how the main characteristics of the structural behaviour play their role within the structural assembly for different degrees of interaction between frame and panels, as well as for intermediate solutions with dissipative connections. The diaphragm action of the roof system is also investigated by taking into account the actual three-dimensional behaviour of the structure. The results of non-linear static and dynamic analyses under recorded and artificial accelerograms show the seismic performance of the dual frame/wall system with dissipative connections between panels and the effectiveness of the diaphragm action of the roof system.