Passive control of precast building response using cladding panels as dissipative shear walls

Abstract

Current design approaches consider cladding panels (CPs) in precast RC buildings as non-structural elements not interacting with the frame. Frame/CP connections are typically designed only for wind or seismic actions perpendicular to the panel plane; unrestrained displacements in the panel plane are presumed. Past seismic events have clearly demonstrated the inadequacy of this design approach. CPs do in fact interact with the frame, modifying the response of buildings subjected to seismic action. This means that substantial and unexpected forces act on the connections and may lead to connection failure. Evidence of such out-of-plane forces in joints arising in buildings with deformable roof diaphragms is given here. This work proposes using CPs as structural elements to enhance the seismic performance of framed industrial buildings. If the friction acting between the panels is taken into account, CP walls become part of the resisting structure, leading to a dual frame/wall system. This concept can be used both in the design of new buildings and the retrofitting of existing ones. The case study reported here was conducted with CPs arranged horizontally and with pinned connections. We show that the results are highly sensitive to the assumed friction coefficient, and also that they differ substantially from analytical design values obtained disregarding friction effects. Friction between panels is known to be unpredictable, especially when structures are subjected to seismic movement with a strong vertical component. The consequence is that forces and displacements in framed buildings are random in a way which cannot be accepted in structural design. This work therefore proposes control of friction magnitude with suitable devices between panels: CPs can act as resistant and dissipative shear walls in industrial buildings, and are effective and relatively low-cost.