Introduction
Pole installation is a common
requirement of all the smart city
development projects. Installation
of WiFi Hotspots and access
points, Smart lighting systems,
CCTV surveillance camera and
various types of sensors make use
of poles for installations. To make
the process of pole installation
easy and optimized in terms of cost
of installation and time taken for
installation of the same, the white
paper is written to give details of
various options and the finalize
the optimum design for smart city
applications
Criteria for Pole Foundation Selection
This guide is prepared for
conceptual purpose and preliminary
estimating of foundation design for
pole installation only. Determination
of suitability should be based on
actual conditions at site and final
designs for construction purposes
must be validated by a certified
professional engineer.
1. Wind Load Assumptions
Under certain circumstances,
extra assumptions are necessary
to prevent wind induced vibrations
on poles. In steady low wind
speed situations (70-90kmph) with
poles 7 meter or higher have a
higher probability of wind induced
harmonic vibrations. This may cause
poles to fall because of fracture
between the weld and the base
plate. Geographical location may
contribute to this type of vibration;
furthermore open lands are most
susceptible to harmonic vibration
due to wind speed.
2.Cement Concrete
Consideration
Typical poles have a setting depth
based on a definite empirical formula
which comes out to be approx.
21% of pole buried and rest aerial.
Assuming Wind load that pole may
be accustomed to additional support
for grouting pole base by anchor
fastener or HILTI may be provided
for additional strengthening purpose
based on actual site condition
Concrete Grade & Mix:
As per IS 456:2000, the code of
practice for normal and reinforced
concrete, Letter M represents mix
(Concrete Mix) and number followed
after M represents the compressive strength to be attained in N/sq.mm
at 28 days age when a standard
cube of 150X 150 X 150 mm is
subjected to standard compressive
strength. Thus a concrete of M20
grade should attain a compressive
strength of 20N/sq.mm at 28 days of
age. Generally grades of concrete
lower than M20 are not to be used
for RCC work. Here N = Newton, mm
= millimeter.
Concrete Grade:
General expression for the
proportions of cement, sand and
coarse aggregate is 1: n : 2n by
volume.
M5 = 1:4:8 (1 portion of cement,
4 portion of sand and 8 portion of
coarse aggregate)
M10 = 1:3:6 ;M15 = 1:2:4; M20 =
1:1.5:3; M25 = 1:1:2
3. Foundation designs and installation method
Cast in Situ foundation:Basis the
selection of the concrete mix, pole
foundation is cast with anchor bolts
to hold the base plate. Pole is later
fastened to the base plate on the
anchor bolts.
Precast Muff Design
Pre cast RCC Muff is fixed in the
ground and the pole is mounted
inside the Muff with PCC all around
the pole inside the muff. This gives a
faster and economical way to install
the average sized poles upto a
length of 6-12 m poles.
4. Comparison between the above designs
1. Ease of installation- As compared to the Cast in situ option, muff design
is better as it involves lesser labor
and time for installation. RCC takes
a curing time 5-6 days before the
pole can be installed whereas the
muff design takes 2-3 days.
2. Cost of Installation – Comparison
is given below.
5. Recommended Pole
Foundation:
Basis the above analysis and
business requirements, we
recommend to use the Muff design
of pole foundation for all smart city
applications in Smart lighting, CCTV
Camera Installation, WiFi Hotspot
and Access point Installation.
Jitin Rao
Business Excellence
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