Simplified assessment of the pushover curve of a masonry building

Pri oceni potresne odpornosti stavbe je treba ovrednotiti nosilnost in deformacijsko kapaciteto stavbe, ki se lahko oceni s potisno analizo z uporabo nelinearnega modela ali s poenostavljeno potisno analizo. Da bi prispevali k ovrednotenju zmogljivosti slednje analize, smo v diplomski nalogi na poenostavljen način ocenili potisno krivuljo starejše dvoetažne zidane stavbe v Ljubljani. Nosilnost in deformacijsko kapaciteto zidov smo določili v skladu z osnutkom novega standarda Evrokod 8. Upoštevali smo upogibni plastični mehanizem zidu, strižni plastični mehanizem zidu zaradi zdrsa in pojav diagonalnih razpok zidov zaradi strižne obremenitve. Potisne krivulje smo najprej ocenili na nivoju etaž za obe glavni smeri stavbe. Na osnovi deformacije etaž, pripadajočih etažnih prečnih sil in na osnovi predpostavljenega strižnega obnašanja etaže, smo ocenili potisne krivulje stavbe. Analizo smo izvedli z upoštevanjem različnih materialnih karakteristik in različnih porazdelitev horizontalnih sil po višini stavbe. Izkazalo se je, da je za potisno krivuljo stavbe merodajen strižni mehanizem z zdrsom v nadstropju stavbe, kar je posledica majhnih osnih sil v zgornji etaži. Poleg tega se je izkazalo, da se potisne krivulje, ocenjene s poenostavljeno metodo, dobro ujemajo z rezultati nelinearne statične analize, ki je bila opravljena v predhodni študiji.For the assessment of the earthquake resistance of a building, it is necessary to evaluate the load-bearing and deformation capacity of the building, which can be evaluated by pushover analysis using a nonlinear structural model or by simplified pushover analysis. To contribute to the evaluation of the simplified pushover analysis, the pushover curve was assessed for an older two-story masonry building in Ljubljana. The load-bearing capacity of the walls was based on the provisions of the draft of the new Eurocode 8 standard. The flexural failure mechanism of the wall, the shear failure of the wall due to sliding and the appearance of diagonal cracks as a consequence of wall shear forces were taken into account. The pushover curves were first assessed at the story level for both main directions of the building. Based on the story-level pushover curves, the pushover curves of the building were determined by assuming the shear behaviour of the floors. The analysis was carried out considering different material characteristics and different distributions of lateral forces along the building elevation. It was found that the pushover curves are governed by the shear failure with sliding at the top floor, which is the consequence of small axial forces on the top floors. It was also found that the pushover curves estimated with the simplified method match well with those from the nonlinear static analysis carried out in a previous study