Blog

Σ(Ti + 10)ti is the equation for concrete _______.

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 5,040 psf, and the reinforcement is a #7 bar spaced every 12 inches.The bottom of the footing is at a depth of 3 ft below grade.The service dead load is 13 kips/ft, and the service live load is 6 kips/ft.The wall is 16 in. thick.The footing is 16 in. thick.The allowable soil pressure, qa, is 4,500 psf.The soil has a density of 130 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 concrete cube is subjected to biaxial loading. Estimate the compressive strength σ1 if σ2 = 0.2 times the compressive strength, in compression.

Drying shrinkage occurs without the loss of moisture due to hydration reactions inside the cement matrix.

The concrete containing Type I cement in a structure is cured for 4 days at 75°F, followed by 2 days at 60°F. Use the maturity concept to estimate its strength as a percentage of the 28-day strength under standard curing. Maturity is defined as M = Σ(Ti + 50)(ti) where Ti is in degrees F and ti is in days.

A longer yield plateau signifies a _______ brittle material.

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 4 ft below grade.The service dead load is 14.1 kips/ft, and the service live load is 7 kips/ft.The wall is 14 in. thick.The footing is 13 in. thick.The allowable soil pressure, qa, is 5,500 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 = 3,100 psi and fy = 60,000 psi.

A wall footing has the following conditions. Determine the critical bending moment, Mu, at the face of the wall. Assume the footing is 4 ft wide and the pressure that acts on the bottom of the footing is 7,000 psf.The bottom of the footing is at a depth of 2 ft below grade.The service dead load is 14 kips/ft, and the service live load is 7 kips/ft.The wall is 16 in. thick.The footing is 13 in. thick.The allowable soil pressure, qa, is 5,800 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.

Prolonged moist curing leads to the lowest concrete strength.

The concrete containing Type I cement in a structure is cured for 2 days at 54°F, followed by 5 days at 63°F. Use the maturity concept to estimate its strength as a percentage of the 28-day strength under standard curing. Maturity is defined as M = Σ(Ti + 50)(ti) where Ti is in degrees F and ti is in days.