Earthquake resistant connection for masonry infill walls in reinforced concrete frame structures with decoupling elements

Severe damages of masonry infill walls in reinforced concrete frames have been observed after past earthquakes since they are generally installed without specific constructive measures and in full contact to the surrounding reinforced concrete frame. The rigidly attached infill walls become part of the horizontal load-bearing system and influence the global vibration behaviour of the reinforced concrete frame structures. The combination of in- and out-of-plane loading leads to failure of the infill walls, which are usually designed and executed as low-strength walls. This unacceptable situation was the motivation to start the development of a decoupling system which separates the frame and the masonry in fill by means of specially shaped rubbers placed in between the frame and infill. The rubbers allow relative displacements between the frame and infill and prevent at the same time the out-of-plane failure of the infill wall. The article first introduces the setup of the new decoupling system and provides an overview of the load bearing capacities obtained through small specimen tests on components. Thereafter the results of full scale tests on reinforced concrete frames, filled with highly thermal insulating bricks, are presented for separate and combined in-plane and out-of-plane loading conditions. Finally the functionality and effectiveness of the system is illustrated by means of a comparison of experimental results obtained for frames with and without decoupling elements.