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Due to how tedious the strength calculations can be for reinforced concrete columns, it is generally preferred to use interaction diagrams to design them.

A rectangular beam has a cross section of b = 18 in., h = 30 in., and d = 27.5 in. It is reinforced with three No. 5 Grade 60 bars. The concrete strength is 6,100 psi (normal weight). The beam has Grade 60 No. 3 stirrups. Determine the cracking moment, Mcr.

Rust does not cause cracks to expand because it occupies the same volume as the metal from which it is formed.

The textbook author recommends the use of 180° stirrups throughout, except in certain cases where 90° stirrups are needed to prevent overlap.

Tied columns have lower ductility giving less warning before a failure.

In a typical construction cycle, the reinforcement and concrete for the columns are placed after the reinforcement and concrete for the beams and slabs in a floor system above it.

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

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

Strength limit states deal with collapse of the structure, whereas serviceability limit states deal with disruption of the use of the structure but not collapse.

Determine the maximum axial strength φPn,max for the following tied column.Column width, b = 20 in.Column thickness, h = 24 in.Number of longitudinal bars = 4Size of longitudinal bars = No. 8Size of ties = No. 4Concrete strength = 7,000 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 60,000 psi