engleski

Static and Buckling Analysis of Concrete Spherical Shells

The existence of large-scale computer programs makes it possible to study non-linear behaviour in thin shell concrete structures. A finite element analysis, including static and buckling analysis is presented for several notable concrete spherical shells around the world, such as the Kresge – MIT auditorium in Boston, USA, the Ehime Public Hall in Matsuyama, Japan and the Het Evoluon in Eindhoven, Netherlands. Also, the structural optimization study of these shells was performed for thickness distribution and structure shape to reduce overall tensile stress, deflection and reinforcements. These successful structures were built during the 1950s and 60s, without the use of computers, but with sound engineering knowledge and judgment in structures, structural behaviour, and construction practice. Numerical implementation of finite element analysis using the Sofistik structural analysis software allows us to examine the viability of concrete shells for today. The finite element analysis in this paper demonstrates that structural optimization leads to a more efficient design of the analyzed concrete spherical shells and that such a tool is useful for designing thin shell concrete structures. An analysis according to the third-order theory which contains non-linear analysis plus analysis according to the second-order theory and additionally the effects of the geometrical system modification, e.g. snap through, length modification for big deformations, and behaviour after buckling was also conducted. Non-linear effects (e.g. plasticising, cracks) can be analysed only with iterations, and this is done in Sofistik software with a modified Newton method with constant stiffness matrix. An ultimate load iteration in geometrical non-linear analysis of these structures with and without imperfections was performed. To take into account the possible plastification of the material an analysis with non-linear material can also be performed simultaneously with the geometrically non-linear analysis. This helps in developing an understanding of the structural behaviour and helps to identify all potential failure causes using failure analysis.

static analysis; buckling analysis; structural optimization; concrete shells; spherical shells

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