Experimental testing of decoupled masonry infills with steel anchors for out-of-plane support under combined in-plane and out-of-plane seismic loading. (7th February 2022)

• Record Type: Journal Article
• Authors: Marinković, Marko; Butenweg, Christoph
• Is Part Of: Construction & building materials. Volume 318(2022)
• Publication Date: 2022-02-07
• Subjects: Masonry infill -- Reinforced concrete frame -- Earthquake -- INSYSME -- Decoupling -- Elastomers -- IMES -- Experimental tests; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.126041
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: In the paper the in-plane and out-of-plane response of decoupled masonry infills with steel anchors is investigated by means of experimental tests; Specimens were subjected to separate, sequential and simultaneous in-plane and out-of-plane loading; Due to the decoupling with elastomers, infill activation is rather low and it is postponed to high drift levels; Out-of-plane connection of infill walls with steel anchors proved effective for pure out-of-plane load but in a case of simultaneous in-plane and out-of-plane loading anchors produce negative effects to the infill walls and infilled frame capacity. Abstract: Because of simple construction process, high energy efficiency, significant fire resistance and excellent sound isolation, masonry infilled reinforced concrete (RC) frame structures are very popular in most of the countries in the world, as well as in seismic active areas. However, many RC frame structures with masonry infills were seriously damaged during earthquake events, as the traditional infills are generally constructed with direct contact to the RC frame which brings undesirable infill/frame interaction. This interaction leads to the activation of the equivalent diagonal strut in the infill panel, due to the RC frame deformation, and combined with seismically induced loads perpendicular to the infill panel often causes total collapses of the masonry infills and heavy damages to the RC frames. This fact was the motivation for developing different approaches for improving the behaviour of masonry infills, where infill isolation (decoupling) from the frame has been more intensively studied in the last decade. In-plane isolation of the infill wall reduces infill activation, but causes the need for additional measures to restrain out-of-plane movements. This can be provided by installing steel anchors, as proposed by some researchers. Within the framework of European research project INSYSME (Innovative Systems for Earthquake Resistant Masonry Enclosures in Reinforced Concrete Buildings) the system based on a use of elastomers for in-plane decoupling and steel anchors for out-of-plane restrain was tested. This constructive solution was tested and deeply investigated during the experimental campaign where traditional and decoupled masonry infilled RC frames with anchors were subjected to separate and combined in-plane ‬and out-of-plane loading. Based on a detailed evaluation and comparison of the test results, the performance and effectiveness of the developed system are illustrated.