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04.13: Influence of closely spaced ring‐stiffeners on the axial buckling behavior of cylindrical shells
Author(s) -
JägerCañás Andreas,
Pasternak Hartmut
Publication year - 2017
Publication title -
ce/papers
Language(s) - English
Resource type - Journals
ISSN - 2509-7075
DOI - 10.1002/cepa.133
Subject(s) - buckling , stiffening , structural engineering , hydrostatic test , hydrostatic pressure , roof , ring (chemistry) , hydrostatic equilibrium , compression (physics) , range (aeronautics) , engineering , materials science , mechanics , composite material , physics , chemistry , organic chemistry , quantum mechanics
Material efficiency in modern tank constructions often is achieved by combining thin plates with light and heavy ring stiffeners. While the plates are designed to resist hydrostatic pressure, the stiffeners are designed against wind and external pressure. Axial buckling may occur due to high roof loads and wind since very thin plates are prone to a loss of stability. Test results in the 60s and 70s revealed that closely spaced ring‐stiffeners may greatly enhance the axial buckling behavior, allowing for knock‐down factors greater unity. However, until today, no design procedure is available allowing for adopting the beneficial effect of ring stiffeners under axial compression into practical design. In this paper a design procedure is proposed that closes this gap in current design codes. One outcome of the conducted literature study revealed that test results of unstiffened shells may be more closely approximated and is shortly presented. The design procedure for ring‐stiffened shells was then developed from lower bound curves deduced from categorized buckling tests. The results of a parametrical study, that was conducted over a wide range of r/t ‐values, is presented. Imperfection depths up to 10 t were examined using a stiffener spacing of one buckling half‐wave. Especially highly slender stiffened cylinders benefit from ring‐stiffening, showing up to 380% strength gains. Imperfection depths proposed by the current design code were found to be too conservative.