STRUCTURAL MODIFICATIONS
Left: Closeup of damaged tower section.
Center: Temporary reinforcement. Right: Modification drawing for
a guyed tower.
NWTE provides designs and construction
drawings for tower structural modifications. Structural
modifications are sometimes required to accommodate a proposed
condition change or to correct existing structural damage.
The Structural Standard for Antenna
Supporting Structures and Antennas (TIA-222-G and TIA-222-H) requires
a structural analysis to be performed when a tower experiences
one or more of the following changes:
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Change in appurtenance configuration (includes installation
of DTV, FM, or wireless communication antennas)
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Structural modification
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Change in serviceability requirements
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Change in the structure classification to a higher class.
The effects of proposed changes can be
determined by analysis. In some cases, changes result in forces
that exceed capacities of structural members, guy wires, or
foundations. Changes can also have an adverse effect on
serviceability by increasing the levels of wind-induced twist or
sway at critical microwave dish locations. NWTE can provide
efficient and cost-effective modification designs that reduce
deflections and structural member demand-capacity ratios to
acceptable levels.
The constant exposure to weather,
sometimes severe, can result in structural damage including bent
or missing structural members. Exposure to moisture can result
in corrosion on structural members, guy wires and guy anchor
arms, and connection elements. A full-climb condition assessment
as recommended in the design standard will result in detection
of structural damage. NWTE has provided tower
repair/modification designs to restore damaged towers back to
full capacity.
NWTE has provided its telecom and
broadcast clients with various cell and broadcast tower
reinforcement/modification drawing packages, including:
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Guy wire replacement and initial tension adjustment
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Vertical pipe leg grouting & reinforcing
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Diagonal and horizontal bracing replacement
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Mid-bay redundant bracing installation
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Emergency guy anchor replacement for corroded anchor arms
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Repair of damaged connection gussets
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Replacement of deficient connection bolts with new high
strength bolts
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Installation and replacement of torque arms to reduce twist
and sway deflections
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Installation of temporary frames to brace damaged tower
sections
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Stiffener weldments for monopole base plates
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Modifications to foundations at tower base and guy anchors
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Installation of new sections to extend tower height
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Design of mounting frames for the installation of Digital
Television (DTV) antennas
Click here to view a slideshow of deficiencies found during tower climbs.
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Click here to view a slideshow of upgraded tower sites.
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