Flexible joints for resilient infilled RC frames: preliminary analyses for shaking table testing

Masonry infills are among the most vulnerable components of building frames, often undergoing severe damage even under minor or moderate seismic shaking. In recent years, flexible joints have emerged as a promising technique for protecting the infills from damage. To fully demonstrate the effectiveness of this technique, it is necessary to carry out full-scale tests on a structural prototype under realistic loading conditions, which can be simulated with shaking table testing. There is also a need to assess whether the joints can provide enough energy dissipation capabilities to enable a resilient-based design of infilled frames. The ERIES-FLEJOI project aims to address these gaps by investigating the performance of two promising systems based on flexible joints, one aimed at increasing the compliance of the infills, the other aimed at decoupling them from the frame. These systems, installed in two identical reinforced concrete (RC) frame prototypes, will be tested at the Dynamic Testing Laboratory of IZIIS (Skopje, N. Macedonia). This paper illustrates the two systems, the preliminary investigations, and the numerical analyses carried out to design the joint systems in order to meet the performance objectives and constraints posed by the shaking table capacity. The analyses involve two recently developed alternative modelling strategies, one based on a meso-scale description of the infill walls and the other on an equivalent discrete macro-element.