Blog

To account for the effect of accidental moments, the ACI Code specifies that the maximum load on a column must not exceed 0.85 times the axial-load capacity of tied columns and 0.8 times the axial-load capacity of spiral columns.

A common example of a column that supports axial forces and bending about two perpendicular axes is a(n) _______.

A wall footing has the following conditions. Determine the required development length, ld, for the reinforcement. Assume the footing is 3 ft wide, the pressure that acts on the bottom of the footing is 7,333 psf, and the reinforcement is a #8 bar spaced every 12 inches.The bottom of the footing is at a depth of 5 ft below grade.The service dead load is 9 kips/ft, and the service live load is 7 kips/ft.The wall is 12 in. thick.The footing is 15 in. thick.The allowable soil pressure, qa, is 6,000 psf.The soil has a density of 120 lb/ft3.The concrete has a density of 150 lb/ft3.The concrete cover has a thickness of 3 in.f’c = 3,300 psi and fy = 60,000 psi.

A wall footing has the following conditions. Determine the required cross-sectional area of shrinkage and temperature reinforcement. Assume the footing is 5 ft wide, the pressure that acts on the bottom of the footing is 5,920 psf, and the reinforcement is a #4 bar spaced every 12 inches.The bottom of the footing is at a depth of 5 ft below grade.The service dead load is 14 kips/ft, and the service live load is 8 kips/ft.The wall is 10 in. thick.The footing is 14 in. thick.The allowable soil pressure, qa, is 5,400 psf.The soil has a density of 110 lb/ft3.The concrete has a density of 150 lb/ft3.The concrete cover has a thickness of 3 in.f’c = 3,700 psi and fy = 60,000 psi.

A wall footing has the following conditions. Determine the pressure that acts on the bottom of the footing. Assume the footing is 4 ft wide.The bottom of the footing is at a depth of 3 ft below grade.The service dead load is 11.8 kips/ft, and the service live load is 6.1 kips/ft.The wall is 16 in. thick.The footing is 15 in. thick.The allowable soil pressure, qa, is 5,900 psf.The soil has a density of 110 lb/ft3.The concrete has a density of 150 lb/ft3.The concrete cover has a thickness of 3 in.f’c = 4,000 psi and fy = 60,000 psi.

A wall footing has the following conditions. Determine the distance to the neutral axis, c, measured from the top of the footing. Assume the footing is 4 ft wide, the pressure that acts on the bottom of the footing is 4,599 psf, and the reinforcement is a #6 bar spaced every 12 inches.The bottom of the footing is at a depth of 5 ft below grade.The service dead load is 6 kips/ft, and the service live load is 7 kips/ft.The wall is 16 in. thick.The footing is 16 in. thick.The allowable soil pressure, qa, is 4,200 psf.The soil has a density of 115 lb/ft3.The concrete has a density of 150 lb/ft3.The concrete cover has a thickness of 3 in.f’c = 4,000 psi and fy = 60,000 psi.

A wall footing has the following conditions. Determine the required development length, ld, for the reinforcement. Assume the footing is 6 ft wide, the pressure that acts on the bottom of the footing is 4,733 psf, and the reinforcement is a #8 bar spaced every 12 inches.The bottom of the footing is at a depth of 4 ft below grade.The service dead load is 13 kips/ft, and the service live load is 8 kips/ft.The wall is 12 in. thick.The footing is 11 in. thick.The allowable soil pressure, qa, is 4,000 psf.The soil has a density of 125 lb/ft3.The concrete has a density of 150 lb/ft3.The concrete cover has a thickness of 3 in.f’c = 3,900 psi and fy = 60,000 psi.

Use the interaction diagrams found in Appendix A of the textbook to determine whether the following circular spiral column can safely support a load of Pu = 254 kip and Mu = 229.0 kip-ft.h = 18 in.fc’ = 4 ksify = 60 ksiγ = 0.9ρg = 0.01

A wall footing has the following conditions. Determine the critical bending moment, Mu, at the face of the wall. Assume the footing is 5 ft wide and the pressure that acts on the bottom of the footing is 4,880 psf.The bottom of the footing is at a depth of 2 ft below grade.The service dead load is 11 kips/ft, and the service live load is 7 kips/ft.The wall is 10 in. thick.The footing is 11 in. thick.The allowable soil pressure, qa, is 4,600 psf.The soil has a density of 125 lb/ft3.The concrete has a density of 150 lb/ft3.The concrete cover has a thickness of 3 in.f’c = 3,400 psi and fy = 60,000 psi.

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 = 12 in.h = 22 in.Clear cover to ties = 1.5 in.Number of longitudinal bars = 6Size of longitudinal bars = No. 8Size of ties = No. 3Concrete strength = 2,500 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 60,000 psi