Reconciliation Of Bernoulli s Equation In Channel Flow: An ...
Ten PrincipleExperimental verification of Bernoulli equation (Prof. M
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7/24/2019 Ten PrincipleExperimental verification of Bernoulli equation (Prof. M
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Chapter Materials and Systems for Prestressing
2 11 CIRCULAR PRESTRESSING
Circular prestressing involves the development of hoop or hugging compressive stresses
on circular or cylindrical containment vessels, including prestressed water tanks and
pipes.
It is
usually accomplished by a wire-wound technique, in which the concrete pipe
or tank is wrapped with continuous high-tensile wire tensioned to prescribed design lev
els. Such tension results in uniform radial compression that prestresses the concrete
cylinder or core and prevents tensile stresses from developing in the concrete wall section
under internal fluid pressure. Figure 2.29 shows a preload circular tank being prestressed
by the wire-wrapping process along its height.
2 12 TEN PRINCIPLES
The following ten principles are taken from Abeles (Ref. 2.32) and applicable not only to
prestressing concrete but to any endeavor that the engineer is called upon to undertake:
1. You cannot have everything. (Each solution has advantages and disadvantages that
have to be tallied and traded off against each other.)
2.
You
cannot have something for nothing. (One has to pay in one way or another for
something which
is
offered as a free gift into the bargain, notwithstanding a solu
tion's being optimal for the problem.)
3
It is never too late (e.g.,
to
alter a design, to strengthen a structure before it col
lapses, or to adjust or even change principles previously employed in the light of in
creased knowledge and experience).
4 There is no progress without considered risk. (While it is important to ensure suffi
cient safety, overconservatism can never lead to an understanding of novel struc
tures.)
5. The proof of the pudding is in the eating. (This is in direct connection with the pre
vious principle indicating the necessity of tests.)
6 Simplicity
is
always an advantage, but beware of oversimplification. (The latter may
lead to theoretical calculations which are not always correct in practice, or to a fail
ure to cover all conditions.)
7 Do not generalize, but rather qualify the specific circumstances. (Serious misunder
standings may be caused by unreserved generalizations.)
8. The important question
is
how good, not how cheap an item
is
(A cheap price
given by an inexperienced contractor usually results in bad work; similarly, cheap,
unproved appliances may have to be replaced.)
9. We live and learn. (It is always possible to increase one's knowledge and experi
ence.)
10. There
is
nothing completely new. (Nothing
is
achieved instantaneously, but only by
step-by-step development.)
SELE TED
REFEREN ES
2.1 American Society for Testing and Materials. nnual book of STM
Standards:
Part 14,
Concrete
and Mineral Aggregates. Philadelphia: ASTM, 1994.
2.2 Popovices,
S
Concrete-Making Materials.
New York: McGraw-Hill,
1979, 1997.
2.3 CI Committee 221. Selection and Use of Aggregate for Concrete. Journal of the American
Concrete Institute
Farmington Hills, MI, 1992.