Numerical modelling of masonry infill walls in existing steel frames

Abstract

It is now widely recognised that masonry infill plays an essential role in the seismic behaviour of existing steel buildings; however, there is still a lack of clear guidance on the modelling of masonry infill in the current Eurocode 8-Part 3. Several methods for the numerical modelling of masonry infills have been proposed in literature over the past few decades, which either adopt a detailed approach (micro-model) or a simplified approach (macromodel). In the former case, bricks are individually modelled, taking into account the brickmortar cohesive interface, which is able to provide detailed insights of the behaviour of masonry infills and the frame-wall interaction but usually at a high computational cost. On the other hand, a simplified model can be easily built within finite element software, most of which replace the infill wall panel with one or more equivalent struts in the diagonal direction. It has been demonstrated that the strut models can simulate RC infilled structures’ global response with acceptable accuracy; however, there are still no adequate recommendations for their modelling within steel frames. Besides, these models are generally incapable of capturing the interactions between the infills and the frame members. To this end, the present paper numerically investigates an Abaqus macro-model of the infilled steel frame, which was experimentally tested as part of the recent SERA HITFRAMES project. The preliminary re-sults shows that the different detailing of steel frames could lead to different damage patterns in the infill walls when compared to RC frames. In particular, instead of a single diagonal strut, at most three struts were observed in this study. The results also suggested that the number and geometry of struts could change with increasing displacement demands, hence it might not be appropriate to use the same strut model for infill walls on different floors