Experimental results of reinforced concrete frames with masonry infills under combined quasi-static in-plane and out-of-plane seismic loading

It is generally known that reinforced concrete frame structures with unreinforced masonry infills frequently suffer severe damage when subjected to earthquake loading. Recent earthquakes show that the damage occurs to both older buildings and new seismically designed buildings. This is somehow surprising as this construction type has been the subject of intensive research projects for decades and simplified verification concepts are available in standards. However, these concepts are based on the separate verification of in-plane and out-of-plane loading although the importance of the design for combined loading conditions is already known. This situation was the reason to perform comprehensive investigations of the seismic behaviour of this traditional construction type for separate and combined in-plane and out-of-plane loading within the framework of the collaborative European research project INSYSME (Innovative systems for earthquake resistant masonry buildings in reinforced concrete buildings). These investigations are helpful to develop innovative approaches to improve the seismic behaviour of infilled frames. This article presents the fundamental project results of experimental investigations on reinforced concrete frames filled with high thermal insulating clay bricks under separate, sequential and combined in- and out-of-plane loading. The test results clearly illustrate that the load-bearing capacity severely depends on the boundary conditions in the connection area between the infill and the frame.