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STRUCTURAL MODIFICATIONS

damaged tower with structural modification

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:

  • Change in appurtenance configuration (includes installation of DTV, FM, or wireless communication antennas)
  • Structural modification
  • Change in serviceability requirements
  • 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:

  • Guy wire replacement and initial tension adjustment
  • Vertical pipe leg grouting & reinforcing
  • Diagonal and horizontal bracing replacement
  • Mid-bay redundant bracing installation
  • Emergency guy anchor replacement for corroded anchor arms
  • Repair of damaged connection gussets
  • Replacement of deficient connection bolts with new high strength bolts
  • Installation and replacement of torque arms to reduce twist and sway deflections
  • Installation of temporary frames to brace damaged tower sections
  • Stiffener weldments for monopole base plates
  • Modifications to foundations at tower base and guy anchors
  • Installation of new sections to extend tower height
  • Design of mounting frames for the installation of Digital Television (DTV) antennas

Click here
to view a slideshow of deficiencies found during tower climbs.

Click here
to view a slideshow of upgraded tower sites.