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Glossary

TermDefinition
AISC 360-16American Institute of Steel Construction specification for structural steel buildings — used for member capacity checks
ASDAllowable Stress Design — design method using unfactored loads with a single safety factor (used by TIA-222-F)
BOMBill of Materials — weight and quantity summary per member type and section
Bracing PatternArrangement of diagonal and horizontal members within a tower panel (Types 1–4)
CaAppurtenance force coefficient — relates appurtenance shape to wind force
CfForce coefficient — relates tower solidity ratio to wind force per TIA-222-H Table 2-8
DOFDegrees of Freedom — independent displacement components per node (6 for 3D: 3 translations + 3 rotations)
EPAEffective Projected Area — wind-catching area of a structure adjusted for solidity and member shape (m²)
FEMFinite Element Method — numerical technique for structural analysis by dividing the structure into elements
FSTDesign Wind Force on Structure = qz × Gh × EPA (kN)
GhGust effect factor — accounts for dynamic wind amplification due to turbulence
KdWind directionality factor — reduces wind load for structures unlikely to experience maximum wind from all directions
KeGround elevation factor — adjusts air density for site elevation above sea level
KzVelocity pressure exposure coefficient — defines how wind speed increases with height based on terrain
KsRooftop speed-up factor — accounts for wind acceleration over rooftop edges for rooftop-mounted structures (TIA-222-H Section 2.6.6)
KztTopographic factor — amplifies wind pressure for towers on hilltops, ridges, or escarpments
LRFDLoad and Resistance Factor Design — design method using factored loads and resistance factors (used by TIA-222-G and TIA-222-H)
P-DeltaSecond-order analysis — accounts for the effect of gravity loads acting on the deformed structure geometry
RrRound member reduction factor — reduces the effective projected area of round members relative to flat members
ServiceNormal operating conditions — used for deflection and serviceability limit checks
Solidity RatioRatio of solid member area to gross panel area on a tower face (ε = Asolid / Agross)
SSTSelf-Supporting Tower — freestanding lattice tower without guy wires
TIA-222-FANSI/TIA-222-F (1996) — ASD-based structural standard for antenna supporting structures; uses unfactored loads and no Kd/Kzt/Ks/Ke factors
TIA-222-GANSI/TIA-222-G (2006) — LRFD-based standard; introduced 3-second gust wind speeds and 1.6W load factor
TIA-222-HANSI/TIA-222-H (2018) — Current LRFD-based standard; 1.0W load factor with recalibrated wind speeds, added Ke and Ks factors
UltimateExtreme (factored) conditions — used for strength limit state checks
Unity RatioUnity Check Ratio = Demand / Capacity. Must be < 1.0 for a member to pass structural checks