In-filled frame structures are commonly used in buildings, even in those located in seismically active regions.
Precent codes unfortunately, do not have adequate guidance for treating the modelling, analysis and design of in-filled
frame structures. This paper addresses this need and first develops an appropriate technique for modelling the infill-frame
interface and then uses it to study the seismic response of in-filled frame structures. Finite element time history analyses
under different seismic records have been carried out and the influence of infill strength, openings and soft-storey phenomenon
are investigated. Results in terms of tip deflection, fundamental period, inter-storey drift ratio and stresses are
presented and they will be useful in the seismic design of in-filled frame structures.