Seismic performance of innovative steel and concrete hybrid coupled shear walls

Steel and concrete hybrid systems are obtained through a combination in series of steel elements and reinforced concrete elements with the aim of exploiting at their best the potentialities of each material. This concept differentiates steel and concrete hybrid structures from steel and concrete composite structures, where steel and concrete are working in parallel in the same structural element, e.g. concrete filled hollows steel columns and steel profiles embedded in reinforced concrete elements. In this work the seismic behaviour of an innovative hybrid coupled shear wall (HCSW) system, developed in the European research project INNO-HYCO (INNOvative HYbrid and COmposite steel-concrete structural solutions for building in seismic area), is investigated. Such earthquake resistant solution is composed by a reinforced concrete wall coupled to steel side columns by means of steel links with the objective to exploit both the stiffness of reinforced concrete wall, necessary to limit building damage under low-intensity earthquakes, and the ductility of steel links, necessary to dissipate energy under medium- and high-intensity earthquakes. The seismic behaviour of the system is assessed through multi-record nonlinear incremental dynamic analysis (IDA). For this purpose, first a set of realistic case studies is designed, then a finite element model is developed into the platform OpenSees and validated through comparisons against experimental tests including local and global responses quantities. The outcomes of the numerical analyses show that the proposed innovative system is actually able to effectively dissipate the energy through the activation of the inelastic behaviour of the steel links before yielding in the reinforced concrete wall.