Innovative hybrid coupled wall systems to resist seismic action – HYCAD

This article summarizes the research carried out in the ongoing HYCAD project, which aims to improve the performances of a hybrid coupled wall (HCW) system for buildings in seismic areas, by further developing the HCW originally studied in the RFCS project INNO-HYCO. This HCW system consisted of a reinforced concrete (RC) wall coupled with two steel side-columns via steel coupling links. Encouraging outcomes were obtained such as: controlled post-elastic ductile behaviour under medium- and high-intensity earthquakes, suitable lateral stiffness, seismic energy dissipation concentrating in the easily-replaceable steel links and very limited damage in the RC wall. However, advanced studies were required to bring this system into practice, addressing issues and develop advancements in the analysis, design, and detailing. This article summarizes the primary steps taken towards that purpose. Five new components were chosen in order to improve the performance of the HCW system: (1) Link-to-wall connections using post-tensioned tendons; (2) Composite walls with encased steel profiles instead of a conventional RC wall; (3) Rocking coupled wall system; (4) Dissipating devices as links and (5) Precast double slab wall systems. Combining these components, four new HCW systems were developed, pre-designed and analysed through numerical and experimental studies. Advanced yet simple techniques were proposed for the numerical analyses while test specimens are used to characterize local and global behaviour.