Numerical Modelling of Masonry Infill Walls in Existing Steel Frames Against Experimental Results

Abstract

The presence of masonry infills may significantly affect the seismic behaviour of existing steel moment-resisting frames, characterised by low lateral force resistance and inadequate energy dissipation capacity due to the lack of seismic detailing. Masonry infills may cause variation of internal force distribution along beams and columns, resulting in large local seismic demands at beam-column joints and consequently leading to soft-storey mechanisms. Several numerical models have been developed to account for the effects of masonry infills, among which the equivalent strut models were most widely used. However, it has been argued that despite its ability to capture the global response of structures, the single-strut model may not be adequate to correctly simulate the internal forces distributions in steel members. To this end, the present study investigates modelling strategies of infilled steel frames using both single- and three-strut models. The results from different modelling approaches are compared among them and with experimental tests, providing insights on the influence of the modelling strategies both at global and local levels.