Innovative decoupling system for the seismic protection of masonry infill walls in reinforced concrete frames

• Published in: Engineering structures Vol. 197; p. 109435
• Main Authors: Marinković, Marko, Butenweg, Christoph
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15.10.2019; Elsevier BV
• Subjects: Bearing capacity; Collapse; Concrete; Concrete construction; Decoupling; Earthquake; Earthquake damage; Earthquake resistance; Earthquakes; Elastomers; Frame structures; Frames; Horizontal loads; Infill masonry; INODIS; INSYSME; Isolating element; Load bearing components; Load bearing elements; Masonry; Masonry construction; Motivation; Redevelopment; Reinforced concrete; Reinforced concrete frame; Research projects; Seismic activity; Walls; Reinforced concrete frame; Decoupling; Earthquake; INODIS; Isolating element; Infill masonry; INSYSME
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2019.109435

•In-plane and out-of-plane response of masonry infilled RC frames is investigated by means of experimental tests, in which specimens were subjected to separate, sequential and combined in-plane and out-of-plane loading.•Traditional infills showed high vulnerability to both sequential and combined in-plane and out-of-plane loading with the high reduction of in-plane drifts, with out-of-plane displacements are highly pronounced.•Innovative system INODIS, based on the decoupling of infill from the frame, successfully provides in-plane decoupling and at the same time out-of-plane restrain.•Infill activation is rather low and it is postponed to high drift levels.•Even after experiencing damage, infill wall with the INODIS system remains stable and does not collapse under 3.25% of in-plane drift. Reinforced concrete frame structures with masonry infills often exhibit serious damage after earthquake events, as the infills are generally installed without additional constructive measures in contact to the reinforced concrete frame. The masonry infills constructed in this way experience an unplanned interaction with the surrounding RC frame and thus become part of the horizontal load-bearing system with in-plane loading. This interaction combined with seismically induced loads perpendicular to the infill panel often leads to total collapses of the masonry infills and heavy damages to the RC frames. This fact was the motivation to develop an innovative system for decoupling the RC frame and the masonry infill with a special profile made of elastomeric cellular material within the collaborative European research project INSYSME (Innovative Systems for Earthquake Resistant Masonry Enclosures in Reinforced Concrete Buildings). The profile allows relative displacements between the RC frame and the masonry infill and serves at the same time as a support for out-of-plane loads. The article first explains the design and installation of the system and provides an overview of the load bearing capacities determined through small specimen tests on the system components. Subsequently, fundamental experimental investigations on traditional and decoupled RC frames infilled with high thermal insulating clay bricks for separate and combined in-plane ‬and out-of-plane loading are presented. Based on a detailed evaluation and comparison of the test results, the performance and effectiveness of the developed system are illustrated.