Seismic lateral deformation and energy demands in bare and infilled RC frames.

In this paper, lateral deformation and energy demands of reinforced concrete frames when subjected to several earthquake ground motions are evaluated by means of numerical analyses. More precisely, 4- storey, 2-bay RC frames, designed for (i) static vertical loads only, and (ii) seismic actions, are studied considering three different conditions, namely bare frame, fully infilled frame and open ground story configuration. Six real accelerograms are considered, focusing on near-fault records. The main outcomes are presented and compared with the demand imposed on single-degree-of-freedom systems. Moreover, the demands imposed on the analyzed models are compared with the corresponding capacities, in order to evaluate the reached structural damage level. It is concluded that the structures benefit a lot from the presence of regularly distributed infills. The presence of an open story is strongly detrimental for the frame designed for vertical loads only, while the aseismic structure is less affected by this irregularity in the infills distribution. The comparison between the displacement and energy demand for MDOF systems with the demand for SDOF systems showed interesting trends, but also large dispersions.