ACI 318-14 Section 25.7.2.1 specifies that ties shall have a center-to-center spacing not exceeding the least of 12db of longitudinal bar, 48db of tie bar, and smallest dimension of member.

A rectangular beam has a cross section of b = 18 in., h = 30 in., and d = 27.5 in. It is reinforced with two No. 7 Grade 60 bars. The concrete strength is 7,600 psi (normal weight). The beam has Grade 60 No. 3 stirrups. Determine the gross moment of inertia, Ig, for the beam.

If a column qualifies as a short column, the effects from slenderness can be ignored.

People exercising can cause vibration problems in buildings.

Almost universally, all of the longitudinal bars in a column are the same size.

Tied columns may be any shape required.

Cracks in a member increase the member’s moment of inertia, thereby decreasing the member’s stiffness.

Use the interaction diagrams found in Appendix A of the textbook to determine whether the following rectangular tied column with bars in 4 faces can safely support a load of Pu = 240 kip and Mu = 80.0 kip-ft.b = 24 in.h = 20 in.fc’ = 4 ksify = 60 ksiγ = 0.75ρg = 0.03

For tied columns in nonseismic regions, ties are spaced roughly the width of the column apart.

A simply supported beam with dimensions of b = 18 in., h = 28 in., d = 25.5 in., and L = 23 ft supports a uniform service (unfactored) dead load of 2.225 kips/ft including its own self weight plus a uniform service (unfactored) live load of 1.4 kips/ft. The beam is reinforced with four No. 8 Grade 60 bars. The concrete strength is 6,700 psi (normal weight). The beam has Grade 60 No. 3 stirrups. Using the effective moment of inertia, determine the immediate mid-span deflection of the beam due to the combined service loads (dead plus live).The effective moment of inertia Ie = 11,798 in.4.