Modeling and Design Issues of Non Load-Bearing Permanent Shuttering Systems with Concrete under Seismic Loads

Since the end of the 60 s non load-bearing permanent shuttering systems based on the use of formwork blocks filled with concrete or panels of insulating material covered with spray-concrete were used across Europe for buildings in non seismic areas.The formwork blocks are laid dry, thereby eliminating the various drawbacks caused by the use of mortar, subsequently filled with concrete, thus ensuring an adequate bearing structure. This construction method with a single operation resolves the problems related to the thermal and acoustic insulation, the thermal inertia and the structural behavior; this last taking advantage of the characteristics of the concrete used for the filling. These characteristics provide living comfort and savings on the heating costs. Same advantages characterize the permanent shuttering systems realized spraying concrete, which performs as load-bearing element, on panels of insulating material (such as polystyrene). Extension of the use of such construction techniques in the seismic regions is now envisaged: for this reason, series of experimental tests, both quasi-static and dynamic, are currently under development together with numerical studies. This paper presents the part of the work which faces several issues such as the development of guidelines for the finite element modeling, the evaluation of the internal actions and the design. Key problem is the sought balance between simplicity and accurateness of the model and between the straightforwardness of the design procedure and the resultant structural safety. The research presented in the paper deals with different possible modeling solutions (i.e. frame macro-elements or shell elements), their drawbacks and advantages, looking for a computationally efficient model. Furthermore performance requirements and design rules are discussed as an essential part of the guidelines under development. Finally, a software for the computer-aided design, from the geometrical modeling to the design of structural details, is briefly described