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

Tied columns are used when ductility is important or where high loads make it economical to utilize the extra strength from the higher φ factor.

Determine the required splice length for the epoxy-coated longitudinal bars in the following tied column made of lightweight 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 = 18 in.Clear cover to ties = 1.5 in.Number of longitudinal bars = 14Size of longitudinal bars = No. 7Size of ties = No. 3Concrete strength = 7,500 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 40,000 psi

A simply supported beam with dimensions of b = 16 in., h = 28 in., d = 25.5 in., and L = 20 ft supports a uniform service (unfactored) dead load of 1.766667 kips/ft including its own self weight plus a uniform service (unfactored) live load of 1.0 kips/ft. The concrete is normal-weight concrete. The beam is reinforced with 5 No. 8 bars. The concrete strength is 3,400 psi, and the yield strength of the reinforcement is 60,000 psi. Determine the maximum applied bending moment due to the combined service loads (dead plus live), Ma.      

Spirals are normally made from Grade-_____ steel.

Designers should compute the interaction diagram for the least favorable bar orientation in a circular column because they have little to no control over how the bars are actually installed.

Compute the maximum bar spacing, s, to control for cracks in a one-way slab with 1.5 in. of clear cover and f​y​ = 70 ksi.

Weakening of concrete near the top of a column is due to upward migration of water in the fresh concrete.

Column ties increase the unsupported length of the longitudinal bars, thus reducing the danger of buckling.

Spiral columns are often used in situations where ductility is unimportant.