Innovative hybrid and composite steel-concrete structural solutions for building in seismic area

The INNO-HYCO research project aims at defining innovative steel and reinforced concrete hybrid systems for construction of feasible and easy repairable buildings in seismic zones, able to fully exploit the stiffness of concrete components and the ductility, dissipation capacity, and replaceability of steel elements. Hybrid coupled shear walls (HCSW) and steel frames with reinforced concrete infill walls (SRCW) are considered. An innovative HCSW system is obtained through the connection of a reinforced concrete wall to side steel columns by means of replaceable steel links acting as dissipative elements. A capacity design procedure based on limit analysis is developed in order to enforce a suitable dissipative mechanism while limiting the wall damage. An innovative SRCW system is derived as an evolution of the system considered in Eurocode 8 through the adoption of solutions capable to overcome its drawbacks as observed in preliminary analyses. The infill walls are connected only at their corners to bearing plates to foster the formation of diagonal concrete struts. The dissipative elements are replaceable portions of the side columns that are not connected to the infill walls. A specific capacity design is developed to avoid the wall crushing. Experimental investigations on the two systems are used to validate the theoretical assumptions and to derive specific nonlinear models for the assessment of the designs based on the proposed procedures. Finally, the two innovative hybrid systems are used in the design of a realistic case study consisting in a 6-storey building in a medium-high seismic area