Adjustment Factors for Bolts
NDS table 10.3.1
Base Conditions
- 10-year duration
- initially dry and remains dry
- normal temperature
- only one bolt per row
- spacing provisions are satisfied
Wet Service Factor, CM
"It is necessary for the designer to understand the material if it is to be used properly."
shrinkage & swelling across the grain + cross-grain tension → bolt arrangement
little shrinkage along the grain
free movement of the bolts across the grain
slotted holes in steel
NDS section 10.3.3
see footnote 3
be careful of shrinkage in dry climates
Group Action Factor, Cg
"each bolt in a row does not carry an equal portion"
Cg ↓ as number of bolts in a row ↑
does not apply to D < 1/4-in.
factors
- n = number of bolts in a row
- N = number of bolts in a connection
- ratio of member stiffnesses
- diameter
- row spacing
- load/slip modulus
Geometry Factor, CΔ
find smallest CΔ for connection
base spacing dimensions (no adjustments) & minimum permitted spacings