In tall buildings, lower strength concrete is generally used in the columns to reduce their size.

Determine the maximum pitch, s, for the spirals in the following circular column.Column diameter, h = 22 in.Clear cover to spirals = 1.5 in.Number of longitudinal bars = 8Size of longitudinal bars = No. 8Size of spiral = No. 4Concrete strength = 6,500 psiYield strength of longitudinal bars = 60,000 psiYield strength of spiral = 60,000 psi

Determine the maximum pitch, s, for the spirals in the following circular column.Column diameter, h = 24 in.Clear cover to spirals = 1.5 in.Number of longitudinal bars = 8Size of longitudinal bars = No. 6Size of spiral = No. 3Concrete strength = 6,500 psiYield strength of longitudinal bars = 60,000 psiYield strength of spiral = 60,000 psi

In seismic regions, ties are normally spaced closed together.

Tied columns are more ductile than spiral columns, giving tied columns a lower strength-reduction factor.

In tall buildings, higher strength concrete is generally used in the columns to reduce their size.

Determine the location of the neutral axis, c, for the following tied column when the largest strain in the concrete is 0.003 and the strain in the tension reinforcement is 0.003.b = 16 in.h = 20 in.Clear cover to ties = 1.5 in.Number of longitudinal bars = 6Size of longitudinal bars = No. 8Size of ties = No. 3Concrete strength = 3,500 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 40,000 psi

In nonseismic areas, tied columns are used more extensively.

Because designers have little control over the arrangement of the bars in a circular column, the interaction diagram should be computed for the least favorable bar orientation.

Misalignment of columns from floor to floor can cause eccentricities in columns.