Columns

 

Column vs Short Column

buckling possible, no buckling

CE 120 short column

 

 

Stress Parallel-to-Grain

f_c = P/A ≤ F'_c
T_u ≤ F'_cnA

use trial size

 

 

Gross vs Net Area

If reduced area (hole) is at braced point...

1. use A_g to check for stability between braces
2. use A_n for f_c with no adjustment for stability

If reduced area is unbraced...

1. use A_n to check for stability
2. use A_n for f_c with no adjustment for stability

 

 

Adjusted Design Values

F'_c = F_c(C_D)(C_M)(C_t)(C_L)(C_F or C_V)(C_fu)(C_c)(C_i)(C_r)(C_P)
F'_cn = F_cK_F(Φ_c)(λ)(C_M)(C_t)(C_L)(C_F or C_V)(C_fu)(C_c)(C_i)(C_r)(C_P)

C_F for compression only applies to Dimension Lumber

 

 

Buckling

l_e/r replaced by l_e/d for rectangular cross sections

r = radius of gyration
d = least dimension of cross section

Euler critical buckling stress

F_cr = π²E / (l_e/r)²

Yliner stress

F_cE = 0.822E'_min / (l_e/d)²

 

 

Crushing

F*_c = F_c(C_D)(C_M)(C_t)(C_L)(C_F or C_V)(C_fu)(C_c)(C_i)(C_r)(C_P)
F*_cn = F_cK_F(Φ_c)(λ)(C_M)(C_t)(C_L)(C_F or C_V)(C_fu)(C_c)(C_i)(C_r)(C_P)

no C_P

 

 

Interaction Between Buckling and Crushing

F_cE / F*_c
F_cEn / F*_cn

0 ≤ c ≤ 1

c = 0.80 for sawn lumber 
c = 0.85 for round timber poles and piles 
c = 0.90 for structural glued laminated timber or structural composite lumber
c = 1.00 for ideal material loaded under ideal conditions

 

 

Column Inspections