The concrete in the core of a spiral column is subjected to a uniform confining stress σ3 of 270 psi. What will the compressive strength σ1 be? The unconfined uniaxial compressive strength is 3,800 psi.

A wall footing has the following conditions. Determine the moment capacity, Mn, of the footing. Assume the footing is 5 ft wide, the pressure that acts on the bottom of the footing is 5,200 psf, and the reinforcement is a #4 bar spaced every 12 inches.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 8 kips/ft.The wall is 12 in. thick.The footing is 12 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 = 3,200 psi and fy = 60,000 psi.

Concrete near the top of deep members tends to be weaker than the concrete lower down.

A wall footing has the following conditions. Determine the shear capacity, φVn, of the footing. Assume the footing is 7 ft wide, the pressure that acts on the bottom of the footing is 4,000 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 14 kips/ft, and the service live load is 7 kips/ft.The wall is 14 in. thick.The footing is 12 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.

A wall footing has the following conditions. Determine the pressure that acts on the bottom of the footing. Assume the footing is 5 ft wide.The bottom of the footing is at a depth of 3 ft below grade.The service dead load is 14.4 kips/ft, and the service live load is 6.2 kips/ft.The wall is 14 in. thick.The footing is 10 in. thick.The allowable soil pressure, qa, is 5,300 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 = 3,700 psi and fy = 60,000 psi.

A wall footing has the following conditions. Determine how much greater the factored load is than the unfactored load.The bottom of the footing is at a depth of 2 ft below grade.The service dead load is 13.1 kips/ft, and the service live load is 8 kips/ft.The wall is 12 in. thick.The footing is 10 in. thick.The allowable soil pressure, qa, is 4,100 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 = 3,400 psi and fy = 60,000 psi.

A wall footing has the following conditions. Determine how much greater the factored load is than the unfactored load.The bottom of the footing is at a depth of 5 ft below grade.The service dead load is 13.3 kips/ft, and the service live load is 6.7 kips/ft.The wall is 12 in. thick.The footing is 10 in. thick.The allowable soil pressure, qa, is 4,100 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 = 3,400 psi and fy = 60,000 psi.

A concrete block will eventually break if a constant load is applied at 75% to 80% of its ultimate compressive strength due to _______.

A concrete cube is subjected to biaxial loading. Estimate the compressive strength σ2 if σ1 = 0.8 times the tensile strength, in tension.

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 6,933 psf, and the reinforcement is a #6 bar spaced every 12 inches.The bottom of the footing is at a depth of 2 ft below grade.The service dead load is 8 kips/ft, and the service live load is 7 kips/ft.The wall is 14 in. thick.The footing is 15 in. thick.The allowable soil pressure, qa, is 5,500 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 = 3,200 psi and fy = 60,000 psi.