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[mutyalanaidu at rediff...]

Respected sirs,
I have few doubts, plz clarify them
1) why do we prefer hyperbolic shape to the cooling towers? why not other
2) while designing a r.c.c beam if we get the reinforcement calculated is less than the minimum we will provide minimum reinforcement, my question will it not become over reinforced as we are providing more reinforcement than the required?
3)What is the cretria to be followed to determine the height of the truss in industrial buildings? some the books giving span/5 or some thing if so what is the technical explanation behind it?

regardsmutyalanaidu

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[a_deep]

Dear All,

I have to start the structural design for a 2 B + G + 7 storied (total
height 40 m approx) symmetric building in seismic zone 4 having size in the
range of 65m x 25m. Should I disign with expansion joint/ Separation joint
only or I can start without any joint (with doing the temperature analysis)
as it is a hospital building and the joints are generally the dirty places
of the building.

Also if any literature I can get for temperature analysis, I would be
grateful.
I would also like to know the defletion behaviour of multistoried buildings
10 to 15 storied with change in building plan size. Whether there is any
desirable building height/ width ratio which gives economy in design and
better performance of building during cyclones or earthquakes.

Please advice.

Aman Deep

Posted via Email

[ranna]

yOU CAN GO AHEAD WITHOUT ANY EXPANSION JOINT SINCE THE LENGTH IS ONLY ABOUT 65M AND
YOU CAN ANALYSE IT USING STAAD ADDING TEMP LOAD CASE ALSO.sINCE YOU ARE GOING TO BUIL
THE BLDG WITH RCC MASS&STIFFNESS OF THE BLDG WILL BE HEAVIER COMPARED TO STEEL
STRUCTURE AND HENCE THER MAY NOT BE A PROBLEM OF VERTICAL DEFLECTION
ranna@bheltry.co.in

a_deep@hsccltd.co.in wrote:

[narzi]

Dear Aman -
Study the architectural geometry - If any abrupt changes then and then go
for expansion joint - but before that studying the plan geometry is must.

Kamal Parekh
Surat
----- Original Message -----
From:
To:
Sent: Friday, November 28, 2003 11:06 AM
Subject: doubt

[jayantseth]

亲爱的Mutyala Naidu。

A cooling tower has to be enclosed device for evaporative cooling of water
by contact with air. For the tower, the circular shape in plan is most
desirable and the stream currents developing naturally is another factor
that governs the efficient geometry of any tower.

双曲线形状提供了巨大的内心的时刻tia and rigidity so there
is considerable resistance to high winds, hurricanes and earthquake.

The shape being doubly curved is not developable will offer more economical
design as shell will be thinner and will require less reinforcement.
Shearing stresses are practically nil.

Compared to next best shape could be conical. However, normal stress along
meridian will be about 25% less in Hyperbolic tower compared to conical.

For all other towers the stress concentration at throat is higher. While
extension of hyperbola from throat stiffens the shell.

Several hyperbolic cooling towers can be constructed close together yet the
high speed wind which occur at some altitude are almsot unrestricted.

Seperation behind the upstream side of the tower is minimised since the
tower width decreases as the wind velocity increases.

The cross section of the base is comparatively large, a smaller gap height
is necessary for the same entrance area and offers less resistance.

The direction of the entering flow is changed progressively and smoothly
from hotizontal and the hyperbolic shape augments stronger current upward.

With state of art in design and construction practices it has become vaible
to provide clients with cost effective hyperbolic cooling towers.

A minimum steel is provided in beam design is good engineering practice and
to take care of many factors in form of shrinkage, creep, and other
unaccounted load that comes due to assumptions made while concrete it self
is hetrogenous. When a need has arised that steel required is less than
minimum this member is needed to share very less load and hence last develop
plastic - hinge.

一个关于桁架高度consider space available, economy and other
parameter. However, stastically if you work out you are more or less close
to span/5 in most of the case.

With regards JAYANT

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