In the master's thesis, we analyze the influence of modelling uncertainties on the pushover analysis using the example of a three-storey reinforced concrete frame building, tested in full scale within the European research project SPEAR. The building represents a type of older construction in Greece and the wider Mediterranean region. It was designed solely for gravity loads, while the design for seismic resistance was not accounted for. In the context of the master's thesis, the term "modelling uncertainties" primarily encompasses various approaches to modelling frame structures and the use of different software. For this purpose, two programs capable of conducting pushover analyses, SAP2000 and 3Muri, were utilised. However, the SPEAR building was modelled in three different ways, gradually increasing the modelling accuracy. The models were employed in free vibration and pushover analysis. The pushover analysis results were applied within the N2 method to determine the limit-state acceleration causing near collapse limit state, in accordance with the currently valid Eurocode 8 and a draft of the new version of the standard. Based on the results, we conclude that 3Muri may be suitable for the analysis of torsionally rigid reinforced concrete structures consisting of regular frames. Problems arise in the case of torsionally flexible structures and structures with irregular frames due to the use of the equivalent frames method. The generated equivalent frames in structures with irregular frames, where the beams are not supported at both ends by columns, can cause incorrect distribution of seismic forces, which can lead to a biased assessment of seismic resistance.
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