Structural engineering design fees are included in the price of a new communications structure. Most manufacturers maintain on-staff engineers using proprietary or third party engineering programs to properly design a monopole, self-supporting or guyed tower. Other firms outsource these professional services.
Hand calculations swiftly exited during the 80s following the introduction of sophisticated software programs that were required to handle demanding workloads and accelerated construction timetables. However, engineers still perform these individual computations to derive or verify output of certain aspects of the project design.
New tower and monopole structures in the United States are designed using national standard TIA/EIA-222-F. Revision G of the structural standard for steel antenna towers and supporting structures will replace the 1996 F revision when it is effective in 2006.
Structural re-analysis studies are in high demand on existing towers and monopoles to identify if the structure is capable of supporting changed or additional loading that is different from the previous installation design. The engineering report, sealed by a professional engineer registered in the state where the project resides, summarizes design criteria, member and anchor bolts factors of safety, and details how the loading affects the tower and foundation.
Reports will provide practical modification suggestions and materials, if feasible. Turn-around times vary. Five business days seems to be an acceptable average providing the engineer receives a full listing of design standards including wind and ice loadings, tower drawings or a complete mapping, in addition to all appurtenances that will be on the new structure. Additional charges are incurred for modification drawings required to bring the tower into design compliance. Budgetary pricing for re-analysis engineering is provided below.
We recommend that you contact our listed structural engineers to obtain additional information about their services, capabilities and experience.
Size, complexity affects re-analysis pricing
Re-analysis pricing depends upon many factors, including the height, type and complexity of the structure, and if an engineering file number or a full set of design plans is available for design analysis. The following table provides budgetary pricing for a standard re-analysis.
| Self Support
Additional load cases for different antennas and heights can be 30% to 40% of the original price. Multiple cases for a structure can bring reduced pricing, however, all requests must be made with the original re-analysis order. For additional information, see Retrofitting Engineering .
An average cost for a water tank structural analysis is $2,500, the same amount that is typically charged for an antenna mount design and detail drawings, or a steel, antenna and coax mapping.
With additional information you might reduce your costs
Some engineering firms and manufacturers have detailed questionnaires that must be completed before they can provide the re-analysis, but each tower has its unique types of appurtenances, antenna and line configurations and other concerns that must also be provided.
Submit as much information as possible, especially ice and design loading standards. Wireless Estimator has provided an ABOUT WIND SPEEDS reference database, but it’s strongly suggested that you check with the local licensing authority. They have the ability to exceed national standards, plus there are special wind loading areas within a county.
Provide as much information as you can so that an accurate analysis can be done. Otherwise, your engineer is going to make assumptions that seldom favor the structure’s loading capabilities.
If you’re providing the engineer with a tower mapping due to non existent drawings, make sure that you provide accurate wall thicknesses for tubular members.