Traditional vs. sliding-joint masonry infilled frames: Seismic reliability and EAL

In reinforced concrete (RC) multi-storey buildings, the important role of the seismic interaction of structural frames with masonry infills has been revealed by several earthquakes and investigated by many authors. Recently, several innovative infill solutions have been proposed to mitigate such interaction, which could result in widespread damage in both the masonry and the RC structure and sometimes jeopardize the building stability and the occupants' safety. One solution consists in the partitioning of the masonry infill into several sub-panels, relatively sliding along specific joints. This paper investigates the seismic assessment of this technological solution in the framework of performance based earthquake engineering. A two-dimensional five-storey RC seismic-resistant frame is selected as case study and the performance is assessed by comparing the responses of the same structure infilled with different solutions, made of sliding joints or traditional masonry, or in the bare configuration. Incremental Dynamic Analyses (IDA) is used for the probabilistic determination of fragility curves of the structures. Results show the seismic fragility and reliability of the different investigated structures, especially addressing the probabilities of occurrence of damage at different limit states and quantifying the associated expected annual loss.