<p>Due
to the slender geometries of aboveground storage tanks, maintaining the
stability under wind gusts of these tanks has always been a challenge.
Therefore, this thesis aims to provide a through insight on the behavior of
tanks under wind gusts using finite element analysis and computational fluid
dynamic (CFD) analysis. The present thesis is composed of three independent
studies, and different types of
analysis were conducted. In Chapter 2, the main purpose is to model the wind
loading dynamically and to investigate whether a resonance can be triggered.
Research on tanks subjected to static wind load have thrived for decades, while
only few studies consider the wind loading dynamically. Five tanks with
different height (<i>H</i>) to diameter (<i>D</i>) ratios, ranging from 0.2 to 4, were
investigated in this chapter. To ensure the quality of the obtained solution, a
study on the time step increment of an explicit dynamic analysis, and a on the
mesh convergence were conducted before the analyses were performed. The natural
vibration frequencies and the effective masses of the selected tanks were first
solved. Then, the tanks were loaded with wind gusts with the magnitude of the
pressure fluctuating at the frequency associating with the most effective mass
and other frequencies. Moreover, tanks with eigen-affine imperfections were
also considered. It was concluded that resonance was not observed in any of
these analyses. However, since the static buckling capacity and the dynamic
buckling capacity has a relatively large difference for tall tanks (<i>H</i>/<i>D
</i>≥ 2.0), a
proper safety factor shall be included during the design if a static analysis
is adopted. </p>
<p> </p>
<p>Chapter
3 focus on the effect of an internal pressure generated by wind gusts on
open-top tanks. Based on boundary layer wind tunnel tests (BLWT), a significant
pressure would be generated on the internal side of the tank shell when a gust
of wind blow through an open-top tank. This factor so far has not been sufficiently
accounted for by either ASCE-7 or API 650, despite the fact that this internal
pressure may almost double the design pressure. Therefore, to investigate the
effect of the wind profile along with the internal pressure, multiple wind
profiles specified in different design documents were considered. The buckling
capacities of six tanks with aspect ratios (<i>H</i>/<i>D</i>) ranging from 0.1 to 4 were analyzed
adopting geometrically nonlinear analysis with imperfection using an arc-length
algorithm (Riks analysis). Material nonlinearity was also included in some
analyses. It was observed that the buckling capacity of a tank obtained using
ASCE-7/API 650 wind profile is higher than buckling capacities obtained through
any other profiles. It was then concluded that the wind profile dictated by the
current North American design documents may not be conservative enough and may
need a revision. </p>
<p> </p>
<p>Chapter
4 investigates how CFD can be applied to obtain the wind pressure distribution
on tanks. Though CFD has been widely employed in different research areas, to
the author’s best knowledge, only one research has been dedicated to
investigate the interaction between wind gusts and tanks using CFD. Thus, a
literature review on the guideline of selecting input parameter for CFD and a
parametric study as how to choose proper input parameters was presented in
Chapter 4. A tank with an aspect ratio of 0.5 and a flat roof was employed for
the parametric study. To ensure the validity of the input parameters, the
obtained results were compared with published BLWT results. After confirming
that the selected input parameters produces acceptable results, tanks with
aspect ratio ranging from 0.4 to 2 were adopted and wind pressure distribution
on such tanks were reported. It was concluded that the established criteria for
deciding the input parameters were able to guarantee converged results, and the
obtained pressure coefficients agree well with the BLWT results available in
the literature. </p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/8025884 |
| Date | 14 May 2019 |
| Creators | Yen-Chen Chiang (6620447) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/Studies_on_Aboveground_Storgae_Tanks_Subjeected_to_Wind_Loading_Static_Dynamic_and_Computational_Fluid_Dynamics_Analyses/8025884 |
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