Column Design
Reinforced concrete columns carry axial loads and sometimes bending moments. Columns are classified as short (no buckling) or slender (buckling considered). Interaction diagrams show the relationship between axial load (Pn) and moment capacity (Mn) for a column. Spiral columns have higher ductility than tied columns. Tie spacing and lap splice requirements are specified in building codes.
Knowledge Check
1.A short tied column has gross area Ag = 200,000 mm², Ast = 4,000 mm², f'c = 35 MPa, and fy = 420 MPa. What is the nominal axial capacity (Pn)?
2.What is the minimum longitudinal reinforcement ratio for a reinforced concrete column?
3.The maximum longitudinal reinforcement ratio for a column is typically:
4.Which type of column provides greater ductility?
5.What is the minimum number of longitudinal bars required in a circular tied column?
6.The maximum spacing of ties in a column is limited to:
7.A slender column is one where:
8.In a column interaction diagram, the vertical axis represents:
9.The second-order (P-Δ) effects in slender columns are caused by:
10.What is the purpose of the 0.80 factor in the formula Pn = 0.80 × [0.85 × f'c × (Ag - Ast) + Ast × fy] for tied columns?