Civil Engineering Reference
In-Depth Information
Signifi cant repair work should be addressed by the Purchaser and pos-
sibly the Manufacturer to ensure the adequacy and durability of the
repair. Damage that can affect the structural integrity and longevity of the
pole or its components should be reported to the Purchaser immediately.
Field crews should not attempt repair of this type of damage without fi rst
being advised of the proper repair procedure and obtaining the engineer's
permission. The pole may need to be analyzed to determine its suitability
and whether replacement is necessary.
Damage
The location, size, and shape of a crack/damage may be critical to the
structure's performance. Cracks or damage of concern should be initially
reviewed by the Purchaser's qualifi ed inspector. Further investigation,
when required, should be performed by a licensed professional engineer
who is familiar with the requirements of the specifi c structure.
There are two basic types of damage to concrete that normally occur:
local spalling and cracks. Local spalling is where a small area of the con-
crete has been broken away, typically as a result of an isolated high-impact
load. When concrete has spalled, a void is made in the concrete wall of
the pole.
The other type of damage that may occur is cracking. Cracks may be
longitudinal (up and down the pole), or circumferentially around or par-
tially around the pole. Cracking during construction typically occurs
when the pole has been overstressed during transportation, handling, or
installation. Cracks that appear after the pole is in service can be the result
of severe storms, very high winds, impact loads, incorrect installation,
misuse, or defects, and other causes. Circumferential cracks through the
thickness of the concrete may or may not expose a small portion of steel
reinforcement. These cracks, when caused by temporary overload, tend
to close and naturally seal, minimizing possible corrosion. Circumferen-
tial cracks that remain open for a period of time suggest possible perma-
nent overloading of the section and require the Purchaser's review to
correct and repair the crack or replace the pole. Longitudinal cracks
should be closely monitored. Should a longitudinal crack open suffi -
ciently and have a signifi cant length, the rate of possible corrosion of the
steel reinforcement can be much greater. Cracks may vary in width from
being barely visible to easily visible with the naked eye. If the crack is
short and barely visible, it probably does not propagate through the thick-
ness of the concrete. Many hairline cracks that are long in length may not
require repair. If the cracks appear to close after installation, normally no
further repair is necessary. Larger cracks that appear to remain open
should be monitored and possibly repaired.
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