# concrete design

1. True or false: ACI only permits tension-controlled failure modes in columns.

1. What is the φ factor for a spiral column?

1. Name the 4 principles used to calculate the strength of a column.

1. How do the equilibrium equations for a column have to be adjusted compared to the equilibrium equations for a beam?

1. In addition to axial load and the primary bending moments from the applied loads, what other effect must long (slender) columns be designed for?

1. How does ACI classify a column as long or short?

1. In a short column, what factors control the maximum load supported?

1. Describe what causes the secondary P-Δ moment in a long column.

1. Name three types of columns.

1. Describe a composite column.

1. True or false: ties increase the strength of a column.

1. Are tied or spiral columns better for earthquake-prone areas?

1. Why is the failure mode of a spiral column more ductile than the failure mode of a tied column?

1. What is the equation for axial load capacity of a reinforced column?

1. Why is the capacity reduction factor φ smaller for a column than for a beam?

1. Why does the ACI Code limit the design capacity of an axially loaded column to 80 or 85 percent of its actual strength?

1. What are the maximum and minimum percentages of steel that ACI permits a column to be reinforced with?

1. From a practical standpoint, what is the minimum possible column dimension?

1. What is the smallest size tie permitted by the ACI Code for the column shown? What would be the required spacing of those ties?

1. True or false: the confining effect of spiral reinforcement causes the concrete compressive strength to increase.

1. Define plastic centroid.

1. When is the column capacity reached (i.e. when does failure occur)?

1. True or false: Columns with axial load plus bending moment can have one side of the column cross section in tension and one side in compression.

1. True or false: Columns with axial load plus bending moment can have all of the column cross section in compression.

1. What is an interaction diagram?