Mounting frames, antenna mounts, platforms, etc, shall not be considered as a stiffness irregularity. Method 4 shall be used when the horizontal distance from the base of the structure to any guy anchor point exceeds ft [ m]. An importance factor I shall be determined from Table based on the structure classification listed in Table Determine an appropriate seismic analysis procedure method for the structure from Table Determine the maximum considered earthquake spectral response acceleration expressed as a ratio to the acceleration due to gravity at short periods Ss and at 1 second S1 from 2.
Determine the Site Class based on the soil properties at the site in accordance with Table Modification factors Fa and Fv, based on the Site Class, shall be determined from Tables and respectively.
The design spectral response acceleration at short periods SDS and at 1 second SD1 shall be determined in accordance with 2. Analogy: Rock Site Class A vs. Not a part of the standard. Consider Issues such as — Redundancy — Economic loss — Cost of the structure is inversely proportional to increasing the serviceability requirements of the structure. Section 3. An elastic three-dimensional truss model made up of straight members pin connected at joints producing only axial forces in the members.
An elastic three-dimensional frame-truss model where continuous members legs, K-type bracing horizontals without plan bracing are modeled as 3-D beam elements producing both moments and axial forces in the members while the remaining members which are subjected primarily to axial loads may be modeled as 3-D truss elements producing only axial forces in the members.
Analysis Techniques — What is acceptable? An elastic three-dimensional beam-column model producing moments, shears and axial forces in the pole structure. Unless the analysis model considers second order effects within each element, the minimum number of beam elements shall be equal to five per pole section and the maximum beam element length shall not exceed 6 ft.
Note: Due to modeling complexity e. An elastic three-dimensional beam-column where the mast is modeled as equivalent three-dimensional beam-column members supported by cables represented either as non-linear elastic supports or cable elements.
This analysis produces moments, shear and axial forces in the mast, which results in individual member forces. An elastic three-dimensional truss model where individual members of the mast are modeled as straight members connected at joints producing only axial forces in the members.
The cables are represented as cable elements. An elastic three-dimensional frame-truss model where continuous members legs of the mast are modeled as 3-D beam elements producing both moments and axial forces in the members while other members may be modeled as 3-D truss members.
If not what then? Articulation Articulation at both ends of guy assemblies shall be provided for assemblies consisting of non-metallic guys with rigid end connections such as end sockets or similar devices that do not include low frequency dampers.
Articulation shall provide a minimum 10o rotation in both the vertical and the horizontal directions Guy Dampers For guyed masts with structure heights above ft [ m], high frequency dampers shall be provided for cables with rigid end connections such as bridge sockets or similar devices unless otherwise determined by a site-specific analysis.
Values of initial tension beyond these limits may be used provided consideration is given to the sensitivity of the structure to variations in initial tension. The design ambient temperature may be adjusted based on site-specific data. It was the most comprehensive tower standard to date. Design philosophy changed to limit state design from allowable stress design. TIAG also expanded the safety requirements, received international recognition and was referenced in the International Building Code and adopted for use as a base code standard by most jurisdictions in the United States, Bain said in his TIA post.
TIAH provides the industry with critical guidance regarding minimum load requirements and design criteria. View Disclaimer. Response : The table was a unit conversion table. This lead to confusion. Some interpreted the table to represent load combinations. The table listed conversion from Imperial to Metric units. Since conversions were provided in Annex M the tables were removed to avoid confusion.
Removal of the tables had no impact on the design ice thickness and basic wind speed to use for a given location. The ice thickness zones are indicated by solid lines and wind speed zones are indicated by dotted lines. The tables cannot be used as a substitute for the values indicated on the maps. The wind speeds adjacent to ice thicknesses in the conversion tables are irrelevant. The data is simply presented from lowest to highest value and does not specify the wind speed appropriate to consider with a given design ice thickness.
Again, it is important to note that the table is literally a conversion of values, i. Each column is a separate conversion list, not a load combination. About WirelessEstimator. Share Search. Response : TIAG addresses all communication structures regardless of the material used. We do a lot of work on the Atlantic coastline, and these changes would be most beneficial to our clients. Any interpretation of this would be greatly appreciated.
ASCE wind speeds have been reduced in the hurricane coastal areas based on new research. In addition, hurricane coastal areas are now considered as exposure D based on research which has indicated that the roughness of the ocean is more representative of exposure D conditions. In the current version of revision G and previous versions of ASCE 7 the roughness of the ocean was believed to be more representative of exposure C conditions. Sections 2. For example, section 2.
Also, in determining this average height, are all surrounding peaks in a two mile radius included, or only those along the lines of multiple wind directions? For example, we have encountered locations in which using the average height of surrounding peaks to determine the topographic category yields a category 1.
However, along a particular 2 mile upwind path the topography clearly suggests a category 3 or 4. Should the topographic category be determined based on a single wind direction, i. Are the peak heights of the surrounding terrain features measured from the lowest point within the two mile radius?
I restated and numbered each of my questions below to make them easier to reference in your response. In section 2. In determining this average height, are all surrounding peaks in a two mile radius included, or only those along the path of a particular wind direction?
Should the base of a crest height measurement be taken from that point where the slope exceeds 0. Finally, Section 2. Is this correct?
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