Adjustment Factors for Bolts

 

NDS table 10.3.1

 

 

Base Conditions

1. 10-year duration
2. initially dry and remains dry
3. normal temperature
4. only one bolt per row
5. spacing provisions are satisfied

 

 

Wet Service Factor, C_M

"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

1, 2, 3, 4, 5, 6

 

NDS section 10.3.3

see footnote 3

 

be careful of shrinkage in dry climates

 

 

Group Action Factor, C_g

"each bolt in a row does not carry an equal portion"

C_g ↓ 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

 

NDS tables 10.3.6A to 10.3.6D

 

 

Geometry Factor, C_Δ

find smallest C_Δ for connection

base spacing dimensions (no adjustments) & minimum permitted spacings

• end distance
• edge distance
• center-to-center distance
• row spacing

angled connections