Most compression members in concrete are only subjected to uniaxial loads.

The strain will be unequal in the steel and concrete that are bonded together in a symmetrical column subjected to a concentric axial load.

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

Determine the maximum axial strength φPn,max for the following tied column.Column width, b = 20 in.Column thickness, h = 28 in.Number of longitudinal bars = 14Size of longitudinal bars = No. 6Size of ties = No. 4Concrete strength = 3,000 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 60,000 psi

Columns with only two layers of steel and a low steel ratio typically have interaction diagrams composed of straight lines.

ACI 318-14 Section 25.7.2.1 specifies that ties shall consist of a closed loop of deformed bar.

Columns with only two layers of steel and a high steel ratio typically have interaction diagrams composed of relatively straight lines.

Compute the axial compressive strength Pn and moment capacity Mn of the following tied column when the largest strain in the concrete is 0.003 and the strain in the tension reinforcement is 0.003. Note that you should not include φ in the answer and that you should not consider Pn,max.b = 14 in.h = 22 in.Clear cover to ties = 1.5 in.Number of longitudinal bars = 6Size of longitudinal bars = No. 7Size of ties = No. 3Concrete strength = 5,000 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 40,000 psi

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

Reinforced concrete is not elastic and has a compressive strength that is much higher than its tensile strength.