Revision H of ANSI/TIA-222 is Published
By Mark Malouf, PE, SECB, IPF, TR‐14 Committee – Task Group 3 Chair
- October 23, 2017
The ANSI/TIA‐222-H Standard, the “Structural Standard for Antenna Supporting Structures and Antennas and Small Wind Turbine Structures” is a revision of the TIA-222 Standard that builds on the changes introduced in the Rev G and enhances and expands them.
Loading and design strength provisions are revised to be in conformance with changes in the referenced source national standards. Several new annexes are added to address industry practice and requirements.
The new revision of the standard was published on October 19, 2017.
The changes in the upcoming ANSI/TIA‐222-H Standard are summarized as follows:
- Incorporates ASCE 7-16 Standard revised Wind maps with ultimate wind speeds based on risk category and the Wind and Ice Maps. The new wind maps are based on double the amount for wind reporting stations and for longer period of records and reflect better hurricane model simulations. The new maps are based on separation of thunderstorms for statistical analysis in non-hurricane areas and global exposure characteristic at weather stations.
- Updates the load factors to account for the ultimate wind speeds and adds a ground elevation factor.
- Enhances the definitions of the different Risk Categories to clarify associated structures and conditions for the different categories. Adds a new risk category.
- Enhances Section 2 (Loads) provisions including Exposure Categories based on surface roughness, more defined Risk Categories, expands Topographic effects approach using 3 methods – simplified, rigorous and site-specific, adds rooftop wind speed-up factor for buildings and refined appurtenances criteria for clusters.
- Updates and enhances the Seismic section 2.7 to be in conformance with ASCE 7-16 and ACI 318-14 standards to include the updated ground acceleration maps and simplified irregularities. Eliminates the exception for seismic loading analysis in low seismic regions and vertical seismic force analysis now required.
- Updates Section 4 (Design Strength) requirements for changes in the Steel Standard, AISC 360-16, revises the torsional/flexural buckling strength for double angles, bolt shear strengths, refined bracing effective length criteria, revised anchor rods interaction equations and adds a new section to address U-bolts design strength. For pole structures, refined the drag factor and the combined stresses and added port opening reinforcing and minimum flange/base plate strength requirements
- Updates Section 9 (Foundation and Anchorages) for changes to ACI 318-14. Clarifies resistance factors and enhances several provisions including direct embed foundations and ductility requirements in high seismic areas. and maximum eccentricities for mat foundations.
- Updates Section 10 (Protective Grounding) provisions with focus on impedance vs. ground resistance. Provides a new default TIA grounding.
- Updates Section 12 (Climbing Facilities) to be in sync with other safety standards including ASSE A10.48. Addresses obstruction to climbing facilities, fall protection anchorage strength. Clarifies factored strength requirements and provides climbing facility strength and dimensional requirements, including step bolts and their placement on latticed and tubular pole structures.
- Updates Section 15 (Existing Structures) by defining comprehensive structural analysis and feasibility study. Establishes the evaluation of changed condition requirement and the associated baseline appurtenances and proposed appurtenances configurations. Allows demand-capacity ratio up to 105% and adds an alternate approach using Target Reliabilities with load modification factors. Requires Modifications to existing structures to be inspected after installation.
- Addition of new Section 16 for Mounting Systems to address their criteria – load combinations that includes maintenance load, analysis models and application of forces, effective projected areas, seismic load effects and documentation requirements.
- Incorporates and enhances the Tubular Pole Base Plate from Revision G Addendum 3 as a new Annex Q and the Small Wind Turbine Structures from Revision G addendum 4 as a new Section 17.
- Addition of new annexes for Wind Induced Structural Oscillations (Annex M), New Initial Construction Inspection (Annex N), Existing Structures Modification Inspection (Annex O) and Tubular Pole Weld Toe Crack Evaluation (Annex P).
- Updates to the other sections and annexes to reflect changes in the main sections of standard.