Lessons learned from the testing of RC frames with masonry infills and proposals for new solutions / Untersuchungen an mit Mauerwerk ausgefachten Stahlbetonrahmen und neue Lösungsvorschläge

Past experience has shown that inadequate design of unreinforced masonry walls (URM) or inadequate selection of materials can lead to significant economic losses and fatalities in the case of a strong earthquake. In this context, this paper presents the experimental research that has been carried out with the aim of gaining a better insight into the traditional masonry infill walls commonly built in Portugal. The experimental research includes: (1) shaking table tests on reduced-scale reinforced concrete (RC) buildings with masonry infills with distinct typologies, from traditional solutions to those with enhanced properties and solutions to improve the seismic behaviour; (2) in-plane static cyclic tests on a representative one-storey, one-bay RC frame with masonry infills with distinct typologies but similar to the ones tested in the RC building models.
It was concluded that the typology of masonry walls influences the global behaviour of RC buildings, particularly when there is no connection between masonry infill and RC frame. An appropriate design is necessary to prevent an unforeseen failure mechanism due to shear stresses in the RC columns induced by the infill.
The in-plane cyclic tests showed that render plays a central role in the lateral strength and stiffness. Additionally, it was observed that bed joint reinforcement and reinforced render are important measures for controlling damage but do not significantly influence the in-plane lateral strength and stiffness.