IN-PLANE BEHAVIOUR OF RC FRAMES WITH TRADITIONAL AND DECOUPLED INFILLS: PARAMETRIC STUDY

Masonry infills are used as outer and inner partitions in reinforced concrete (RC) frame buildings. Although regarded as non-structural elements, masonry infills are activated under seismic actions. Because of this activation, masonry infills experience life-threatening damage. Moreover, they affect the seismic response of the whole RC frame structure, as they modify the dynamic characteristics of the structure. An innovative decoupling solution is developed to improve the seismic response of the infilled RC frames. In this paper, the in-plane behaviour of the RC frames with traditional and innovative decoupled infills is investigated by means of the simplified micro-model developed in Abaqus. Firstly, the numerical model is validated against the in-plane experimental tests on the RC frames, fully infilled with traditional and decoupled infill. Afterwards, a parametric study is carried out, focusing on the effect of the brick thickness and infill height-to-length ratio on the in-plane behaviour of the infilled RC frames. The level of the frame-infill interaction is evaluated through a comparison of the numerical results on the referent bare RC frame and RC frames with traditional and decoupled infills. The damage on masonry infills and surrounding RC frames, infill contribution forces and initial in-plane stiffness of the RC frames are observed. Additionally, a distribution of internal forces on the RC frames is evaluated in the post-processing of the results, which represents an important novelty of the study. Numerical results show that the decoupling system significantly reduces the activation of the decoupled infills, for all investigated infill geometries. Furthermore, the overall in-plane response of the RC frames with decoupled infills is very similar to the in-plane response of the bare RC frame up to 2.0 % of in-plane drift, which is certainly not the case for the traditionally infilled RC frames.