In-plane cyclic behaviour of RC frames strengthened with composite sandwich panels

This paper presents an experimental study about the development of a sustainable and multifunctional composite sandwich panel for the rehabilitation of reinforced concrete (RC) buildings from the 1960s to the mid-1980s. For this purpose, the cyclic behaviour of representative RC frames was assessed by performing in-plane quasi-static cyclic tests on three different specimens: (i) a bare RC frame (individual behaviour of the frame); (ii) an RC frame with masonry infill wall (representative of target buildings); and (iii) an RC frame strengthened with an innovative sandwich panel formed by outer wythes in recycled steel fibre reinforced micro-concrete and polystyrene core layer. The results show that, in comparison with the traditional masonry infill wall solution, the proposed rehabilitation solution significantly improved the cyclic performance of the RC frame, reaching higher levels of load carrying capacity (395% vs. 349% increase) and energy dissipation (700% vs. 524% increase). Moreover, the sandwich panel has maintained its structural integrity with low level of damage in its internal load-bearing layer for high values of lateral drift (up to 2.1%).The first author wishes to acknowledge the financial support provided by the Portuguese Foundation for Science and Technology (FCT) and the Eco-Construction and Rehabilitation (EcoCoRe) Doctoral Program through the research grant PD/BD/52657/2014. The authors would like to thank the collaboration and support of the following companies for supplying/producing different components: (i) Twincon (RSF); (ii) Tecnipor (RC-frames); (iii) CiviTest (sandwich panel prototype); (iv) BVT–Rausch and PreConTech (functional GFRP connectors); (v) Sch¨ock Bauteile GmbH (structural GFRP connectors); (vi) Hilti (mechanical and adhesive anchoring systems); and (vii) Danosa/Eurofoam (extruded polystyrene plates). The authors also wish to thank the Structural Laboratory from University of Minho