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Copy of Philippine Electronics Code

Section IV General Strength Requirements
by

Flor Neil Buen

on 10 July 2013

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Transcript of Copy of Philippine Electronics Code

Outline
Results
Discussion
Section IV:
General Strength Requirement

Notes
4.1 General
(cc) photo by Metro Centric on Flickr
(cc) photo by Franco Folini on Flickr
(cc) photo by jimmyharris on Flickr
(cc) photo by Metro Centric on Flickr
Loading Zones
Safety Factors
Transverse Strength
Requirements
Vertical Strength
Requirements
Longitudinal Strength
Requirements
Ultimate strength of
Materials
Detailed Strength
Requirements
This Section establishes provisions
covering mechanical strength
requirements used in conjunction
with electronic equipments with
electronic equipment or systems
either alone or when involved
with electrical power systems.
Building Code
Philippine Electrical Code
Heavy Loading
Area (240 kph)
Medium Loading
Area (200 kph)
Light Loading
Area (160 kph)
Sub-Topics
4.2 Loading Zone
4.2.2 Temperature
Wind pressure on cylindricalsurfaces shall be computed
60% as that flat surfaces. In lattices structure, the exposed area
of the lateral face shal be increased by 50% to allow for pressure
on the opposite side.


4.3 Safety Factors
4.3.1 These are the maximum allowable
ratios of ultimate strength of materials
to the maximum working stress.
Safety factors for Structural Steel
shal be applied as specified in Rule 4.7.2.
Wood members in bending
shal be applied to longitudinal
tension and compression.
4.2.1 Wind Pressure
Temperature at maximum loading shall be considered 27 degrees Celsius.
Maximum temperature 65 degrees Celsius in computing sag in this condition
4.3.2 Safety Factors for line elements upon installation
or reconstruction shall be applied by table 4-1.
4.3.3 Replacement
Lines and parts shall be replaced
or reinforced before safety factors
have been reduced to less than 2/3
of the construction safety factors.
4.4 Transverse Strength
Requirements
4.4.1 Special Provisions
Where it is possible to obtain the required transverse strength
except by the use of side guys or special structures.
4.5 Vertical Strength
Requirements
The loads shall be the structures weight plus
the superimposed weight which they support
plus that which may be added by difference in
elevation of supports
Safety factors in Table 4-1 shall be used in computing for the transverse strength
requirements and in calculating allowable stress and minimum sag.
4.6 Longitudinal Strength
Reuirements
The pull of the conductors shall be considered as that due
to the maximum working tension in them under the loading
conditions specified in Rule 4.2.
4.6.1 Reduction in Stress
Stress may be reduced by increasing conductors sags

4.6.2 Use of Guys and Braces
Supports structures to meet the required longitudinal requirements.
4.6.3 Unbalanced Loads
The use of guys or braces shall aid the poles, towera and other structures that are not normally balanced.
4.6.4 The construction of supports is to withstand the load specified with a safety factor at least 2/3 equal of the safety factors in Rule 4.3.2.
4.7 Ultimate Strength of Materials
4.7.1 Wood
Values used for moduli of rupture for wood in bending conjunction
with the safety factors given in Rule 4.3 shal not exceed those Table
shown in Table 4-2.
4.7.2 Structural Steel
Steel Structures and their connections should be designed and constructed
so that the structures and parts shal not fail or shall be seriously distorted at
any load less than the maximum working loads.
4.7.3 Reinforced Concrete
Reinforcing steel, tensile or compression strength in Kg/square cm
4.7.4 Conductors, Span Wires, Guys, Messengers
Refer to Tables 10-14 for values used for ulitimate strength of wires and cables. If values in not included, the ASTM may be a reference,
if specifications are non existent, the manufacturer can provide given that there had been tests done.
4.8 Detailed Strength Requirements
4.8.1 Poles, Towers and Other Structures
A. Strength

Wood poles
Loading Factor specified in Rule 4.3, maximum stress in Rule 4.2 and safety factor in Rules 4.7.2 and 4.7.3
Poles
Steel Poles
4.7.5 Tower and Pole foundations and footing
The weight of concrete shall not be taken as more than
2322.6 Kg/cubic mm, the weight of earth taken not more than
1441.6 Kg/cubic mm.
B. Setting of Wood Poles
Depths of wood poles setting given in Table 4-3 are applicable to wood set in firm or in solid rocks.
C. Gains
These are provided for increasing surface contact of crossarms
with sound wood poles.
D. Replacement (4.3.3)
4.8.2 Crossarms
A. Material
Wood - Table 4-2
Metal - Structural, cast steel or maleable iron
B. Minimim size
Wood - cross section not less than 7.5x11.5cm
exception cross arm 2 mtr or less in length may be
7x9.5cm
Metal - physical property shall meet the requirements of Rules
4.5,4.6 and 4.7.2, provided thickness shall not be less than 0.23cm
C. Strength
Shall be securely supported by bracing when necessary to
withstand unbalanced vertical loads
D. Replacement (Rule 4.3.3)
4.8.3 Pins and Conductors Fastening
A. Materials
Pin - Insulator pins, corrosion resisting metal.
Fastening - Conductor, corrosion - resisting material
B. Size
Wood Pins - minimum diameter not less than 40mm.
Metal Pins - minimum diameter not less than 12.5mm
Fastening and Tie Wires - not sharp edges when in contact with conductors, shouldn't damage the conductor. Refer to Table 4-4 for size and material of tie wires
C. Strength
Insulator pins and conductors fastening be able to withstand loads.
D. Replacement (4.3.3)

4.8.4 Conductors
A. Material
Corriosion resisting metal not subject to rapid deterioration.
B. Size
Section 5 &7
C.Strength
Conductors - withstand stress and loading.
Sags and tension - not more than 1/2 the breaking strength of the conductor
Splices - with accordance with Table 4-1 except as provided by Rule 4.7.4
D. Replacement (Rule 4.3.3)
4.8.5 Insulators
A. Line - withstand mechanical stress by conductors, wires or structures under loading conditions
B. Guy - shall have mechanical strength at least equal to what is required
C. Replacement (4.3.3)
4.8.6 Guys and Anchors
A. Material - exposed area shall be corossion-resisting material
B. Size - shall be les than as specified in Table 4-5
C. Strength - capable of considerable deflection before failure when used with poles.
D. Replacement (4.3.3)
4.8.7 Messengers and Span Wires
A. Material - stranded of galvanized steel, copper-covered steel or other corrosion - resisting material not subject to rapid deterioration
B. Strength - capable of withstanding tension developed because of the load they support combined with loading conditions.
C. Supports - shal be attached to poles or cross arms
D. Replacement (4.3.3)
4.8.8 Hardware
All pole lines shall be galvanized, otherwise protected by a corrosion - resisting treatment, or of material which is corrosion resistant.
Remember!
In designing structures with electronic devices and materials
we should consider the location of the project area so as to
adequately regard temperature and wind pressure in your calculations.
There are different stresses and tensions of materials,
thus this factors should be kept in mind when dealing with
wood and metals. Safety Factors for each material must be
considered.
There are different strength Requirements to
think about, when the electronic material
is used with poles or towers, braces,
fasteners, guys, wires or anchors and others
should be resistant to stress and tension and
must be corrosion-resistive.
Prevent:
Consider:
Free:
More effective, Less cost
End
Full transcript