Columns are typically built with different amounts of reinforcement in the two faces parallel to the axis of bending.

Determine the maximum axial strength φPn,max for the following circular spiral column.Column diameter, h = 26 in.Number of longitudinal bars = 10Size of longitudinal bars = No. 10Size of spirals = No. 3Concrete strength = 7,000 psiYield strength of longitudinal bars = 60,000 psiYield strength of spirals = 60,000 psi

Determine the required splice length for the galvanized longitudinal bars in the following tied column made of normal-weight concrete. Assume that some of the longitudinal bars are in tension and that the connection should be designed as a Class B contact lap splice. Use ACI 318-14 Table 25.4.2.2 to calculate the development length, and assume that the ties satisfy the Code minimum.Column width, b = 22 in.Column thickness, h = 12 in.Clear cover to ties = 1.5 in.Number of longitudinal bars = 12Size of longitudinal bars = No. 9Size of ties = No. 4Concrete strength = 5,000 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 40,000 psi

When a column is under compression, the column shortens and contracts laterally.

What does the vertical axis of a typical interaction diagram for reinforced-concrete column represent?

Determine the maximum axial strength φPn,max for the following tied column.Column width, b = 28 in.Column thickness, h = 12 in.Number of longitudinal bars = 12Size of longitudinal bars = No. 8Size of ties = No. 3Concrete strength = 4,000 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 40,000 psi

Spiral reinforcement acts to restrain the longitudinal expansion of the column core under high axial loads and delays the failure of the core, making the column more ductile.

A point inside an interaction diagram represents a combination of P and M that will cause failure.

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 = 24 in.Clear cover to ties = 1.5 in.Number of longitudinal bars = 6Size of longitudinal bars = No. 9Size of ties = No. 3Concrete strength = 5,500 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 40,000 psi

To minimize splice lengths, choose the smallest practical bar size and the highest practical concrete strength.