Open Access

Christoph Butenweg (a) https://orcid.org/0000-0002-1478-6476
Marko Marinković (b) https://orcid.org/0000-0001-6902-4842
Nisrein Mukattash (a) https://orcid.org/0009-0003-8689-1851

a RWTH Aachen University, Center for Wind and Earthquake Engineering, Aachen, Germany
b University of Belgrade, Faculty of Civil Engineering, Belgrade, Serbia

ABSTRACT

Masonry infill walls are commonly employed as internal and external partitions in reinforced concrete (RC) frame structures. Despite their widespread use, post-earthquake observations have consistently demonstrated that the interaction between masonry infills and surrounding RC frames can lead to significant and often uncontrolled damage. This behavior highlights the inherent seismic vulnerability of traditional infill systems, which not only contributes to substantial economic losses but also poses serious safety risks. Consequently, there is an urgent need for reliable strategies that mitigate infill-related damage while maintaining structural performance. This study presents the decoupling system, INODIS (Innovative Decoupling System), developed to reduce the interaction between masonry infills and RC frames. The system consists of recycled rubber strips inserted at the interface between the infill and the frame. These flexible interfaces delay the activation of the infill under in-plane seismic loading, thereby limiting force transfer and damage accumulation, while still ensuring out-of-plane safety.
The effectiveness of the proposed solution was investigated through an extensive experimental campaign. In a first step, the connections were investigated under the governing loading conditions by means of small-scale component tests on single masonry units. Cyclic quasi-static tests were carried out on RC frame specimens with both traditional rigidly connected and decoupled infills. The test matrix included configurations with and without openings to cover common architectural variations. The results demonstrate that the decoupling system significantly enhances seismic performance by reducing damage to both the infill and the surrounding frame. In addition, the system was validated under dynamic conditions with shaking table tests subjected to real earthquake records, confirming its robustness and reliability under realistic seismic demands. The experimental findings are complemented by the development of a simplified and safe design approach, which is in line with the design of non-interacting masonry infills in the second generation of Eurocode 8.

Keywords: INODIS, Masonry infill, RC frame, non-interacting infills, seismic safety.