Load Transfer Mechanisms in Wind‐loaded Cylinders

Abstract

Load‐transfer mechanisms in wind‐loaded cylindrical shells are described and interpreted using a simple analytical model. This model generalizes to the higher load harmonics (n>1) the well‐known beam‐on‐elastic‐foundation analogy, which is so useful for axisymmetric pressure loadings. It provides an easily visualized physical model of Vlasov's semimembrane theory; it accurately replicates the most important bending effects in closed thin‐walled cylinders, and it explains in an intuitively appealing way the phenomenon of very long decay lenglhs of edge loadings, which is most pronounced in ovaling modes of deformation. The slowly decaying bending solution of this model can be considered as an improved membrane theory, which automatically transitions to ring bending when the height‐to‐diameter ratio or the load harmonic number is large. This transition from membrane action to ring‐bending behavior is primarily responsible for the moderating influence of shell bending on the membrane stresses in wind‐loaded cylinders. A single shell parameter L/ah/a, which can be regarded as the length of the shell relative to an effective decay length of edge disturbances, fully describes the behavior of wind‐loaded cylinders, according to this simple theory. For the ASCE wind‐load distribution, a fixed‐free cylinder responds essentially as a membrane for L/ah/a, less than about 0.1, and for L/ah/a, about 1.0 the membrane theory overestimates the axial membrane stress at the base by a factor of about 3.