Worker at a tower site

Revision H Tower Standard Q & A

Worker at a tower site

An Interview with William Garrett, PE

William Garrett, PE

An update to the Telecommunications Industry Association’s (TIA) Tower Standard published in October 2017. The new Revision H is anticipated to control tower building standards in most U.S. jurisdictions within two years. William Garrett is Chief Engineer for American Tower’s U.S. Tower Division. With 21 years of experience as a structural engineer, he also serves on the TIA Committee responsible for writing Revision H. William provided an inside look at the new standard by answering some commonly asked questions.

Q. What is TIA-222?

A. The TIA’s manufacturers and suppliers of global telecommunications networks are responsible for developing policy and technical standards―among which is the American National Standards Institute (ANSI) and Telecommunications Industry Association's (TIA) "Structural Standard for Antenna Supporting Structures and Antennas," also known as TIA-222. The TIA’s Engineering Committee TR-14 leads technical changes for this standard. The Tower Standard debuted in 1959, and its last update, Revision G, was published in 2006. Publication of TIA-222-H (Revision H) took place in October 2017.

Q. Why is Revision H important?

A. The TIA Tower Standard is technically complex and very important because it governs analysis and design criteria for tower structures in the U.S. While these criteria uphold the safety of tower structures, they also influence the calculation of equipment loads for tower structures, which can impact capital and operational costs, profitability and service quality for end customers. Implementing changes within Revision H will require serious engineering firepower―American Tower's skilled engineers can help.

Q. Can you describe the level of change Revision H will bring, when compared to the current standard?

A. TIA-222-H is an evolutionary change in improving the areas overseen by the TIA’s TR-14 subcommittees. The new standard takes into account current technology and information. Thus, one of the key items addressed within Revision H is the restriction of "grandfathering" compliance with older versions of the standard. Another change Revision H brings is the requirement of mount analyses. When a tower undergoes a structural analysis due to a changed condition, any related antenna mounts will also be required to have a structural analysis. Revision H does not require the mount analysis be performed by the same entity performing the tower analysis; it does require both analyses be performed prior to approval of the changed condition.

Q. For new collocations, what are some of the potential benefits?

A.

Greater flexibility, increased tower capacity, cost savings and safer sites
Greater flexibility, increased tower capacity, cost savings and safer sites

Q. When is compliance required with Revision H?

A. When TIA-222-H takes effect in January 2018, we will be equipped to begin application of the standard to our sites. It will also become the national standard recognized by the International Building Code (IBC). However, the timing with which Revision H will be required or not by a particular jurisdiction will depend on which version of the IBC has been adopted in that jurisdiction. Most jurisdictions in the U.S. lag no more than two years on IBC adoption. Given compliance to updates is happening more rapidly with today’s digital technologies, it is anticipated that by late 2019 compliance with TIA-222-H will likely be required in most of the country.

Highlights of Changes

Q. How will wind speeds and wind design be affected?

A. Wind affects tower design in a big way, particularly towers at higher elevations that tend to be unsheltered and exposed to extreme gusts and towers on open terrain near the coasts where wind does not break over obstacles. Revision H wind-loading criteria includes coefficients that equate wind pressure effects per altitude, resulting in more accurate wind pressures for towers at higher elevations. It also uses location-based wind speeds per the American Society of Civil Engineers (ASCE) 7-16 values, which are defined within the published wind maps in the 2016 edition of the ASCE’s "Minimum Design Loads for Buildings and Other Structures." This latest edition of the wind maps within ASCE-7 incorporates risk categorization into the wind speeds presented on the maps. In comparison to ASCE-7 2010 (the previous version of the wind maps) a slight wind speed reduction will occur in most areas of the U.S. Areas that may not see a reduction are hurricane-prone regions.

Q. What does a mount analysis entail?

A. Mount analysis, which involves considerable knowledge about mounts, mount connections and other structural components associated with antenna and dish placement on towers, will become a mandatory requirement within Revision H. Mount analysis was not required by past versions of the TIA Tower Standard. American Tower Engineering maintains a vast amount of mapped tower data and can help coordinate mount analysis for our customers.

Q. How does Revision H affect installation of modifications?

A. Under Revision H, installation of modifications will be required to meet the TIA-322 (standard focused on construction engineering) and the American Society of Safety Engineers (ASSE) A10.48 (standard focused on construction means and methods)―while both are existing standards, modification installations were not required to meet these standards under Revision G. These standards require engineered rigging plans for tower work based on the complexity of the modification or component installation. Tower installers will be required to arrange for and adhere to the engineered rigging plans for certain modifications; this will add to the safety of modifications and installations on American Tower assets.

Q. Will Revision H limit the ability to apply an acceptable overstress?

A. Revision H will eliminate this “gray” area by defining allowable overstress percentages. Building codes allow for certain situations where a structure at or near capacity may accept a minor, well-defined addition to loading without requiring structural modification. The TIA Tower Standard has not previously contained specific language defining this situation; however, Revision H will allow for existing infrastructure to run at 105% capacity.

Q. Is there new guidance on defining structure classification?

A. Structure class will now be referred to as Risk Category to better match ASCE-7 and IBC definitions. Within Revision H, wireless towers are defined explicitly as Risk Category II structures.

Q. How are seismic designs affected by Revision H?

A. For seismic design, the Equivalent Modal Analysis (EMA) method has been removed as a seismic analysis option to align with the IBC, which references certain acceptable seismic analysis methods for tower structures―EMA is not one of them. Revision G conflicted with the IBC by allowing the EMA method, and as American Tower adhered to this standard, site modifications could often be required to comply. By striking the EMA method, Revision H aligns itself with the IBC, which most jurisdictions follow, potentially allowing for less required modifications for compliance and more consistency across sites.

How American Tower Can Help

American Tower is equipped to begin application of TIA-222-H, when it takes effect in January 2018. With industry expertise and an in-depth understanding of Revision H, American Tower Engineering is ready to adhere to the more modern approach facilitated by the updated standard.

American Tower Engineering – Your Team for Excellence

American Tower’s in-house Engineering team offers your organization exceptional benefits, including many that can be difficult for service providers and enterprise customers to accomplish and produce.

Experienced team

  • In-house Engineering team
  • Control research, development and oversight of engineering processes, including technical analysis and design and analysis approach methodologies
  • Many staff hold seats on the TIA TR-14 committee and subcommittees (responsible for the creation of TIA-222)

Efficient processes

  • Internal Engineering and CAD resources
  • Proprietary tower analysis software
  • Ability to define issues with Radio Frequency (RF) interference or other RF-related issues prior to installation

Exceptional service

  • Internal resources allow for accurate and timely delivery of customer structural analysis, modification designs, Architectural & Engineering (A&E) drawings and RF reports/analyses
  • Staff with vast industry expertise to support your network development

To submit your own question, please contact us.

To secure a full copy of the TIA's new standard, please visit tiaonline.org

Engineering services in Illinois, New York, North Carolina and Michigan are provided through the associated firm A.T. Engineering Services, PLLC. Engineering services in Connecticut are provided through the associated firm A.T. Engineering Services, LLC.

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