ZACHARI, HAFIZ
(2014)
PENGHITUNGAN KEKUATAN BUCKLING STRUKTUR SILINDER
BERDINDING TIPIS AKIBAT BEBAN TEKAN AKSIAL DENGAN
MELIBATKAN PENGARUH KETIDAKSEMPURNAAN GEOMETRI.
Other thesis, Universitas Andalas.
Abstract
ABSTRACT
This final project mainly focuses on buckling strength calculation of thin walled
cylindrical structures under axial compression. Based on previous researches, there are
two factors that significantly affect buckling strength of cylindrical structure. The first is
geometrical imperfection which is commonly appear on cylindrical wall and the second is
material imperfection of cylindrical structure. The influence of these factors will reduce
buckling strength significantly, even until 70% of linear buckling strength. Because of the
influence of material imperfection is assumed to be constant for the same material,
therefore, the existence of geometrical imperfection becomes the most important factor in
designing of thin walled cylindrical under axial compression.
This final project adopts a ring shape imperfection which is previously developed by
Schneider as the main shape of imperfection. Then, this imperfection is attached on the
wall of cylindrical structures that have a radius to thickness ratio (R/t) between 250 to
1250. The range of dimension is assumed to represent storage structures in the field, such
as tank and silo structure. The imperfection dimension is given under variation of
amplitude of imperfection to the thickness of cylinder, (/t), between 0,2 to 10. Calculation
of buckling strength is performed by a nonlinear numerical analysis based on finite
element technique.
The final result shows that the presence of the geometrical imperfection in the thin walled
cylindrical structures can significantly reduce the buckling strength of the structure. As an
example, for the structures with R/t=250 to 1500, the buckling strength can be reduced
about 20% to 80% of yield strength. The value of the reduction factor is verified by several
design standards that have been widely used in designing thin-walled cylinder, such as the
ECCS 1988, DIN 18800/4 and Eurocode ENV 1993-1-6. Verification shows that the
reduction factor which is obtained through numerical analysis can be very well
approached by the design standards. Therefore, these numerical reduction factors can be
considered to be used in determining the initial prediction of the buckling strength of thin
walled cylindrical structures under axial compressive load for many practical applications
in the field.
Keywords: Cylindrical Shells, Geometry Imperfection, Reduction Factors, Buckling
Strength
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