Blog

The strength reduction factor for tension controlled spiral columns is _____.

Spiral columns have lower ductility giving more warning before a failure.

A rectangular beam has a cross section of b = 16 in., h = 28 in., and d = 25.5 in. It is reinforced with three No. 7 Grade 60 bars. The concrete strength is 5,200 psi (normal weight). The beam has Grade 60 No. 3 stirrups. Determine the assumed modulus of elasticity of the concrete, Ec.

Why is the concrete near the top of a column weaker than the concrete in the rest of the column?

Compute the maximum bar spacing, s, to control for cracks in a one-way slab with 2.4 in. of clear cover and f​y​ = 68 ksi.

A rectangular beam has a cross section of b = 14 in., h = 24 in., and d = 21.5 in. It is reinforced with three No. 7 Grade 60 bars. The concrete strength is 6,400 psi (normal weight). The beam has Grade 60 No. 3 stirrups. Determine the neutral axis location of the cracked beam (measured from the top of the beam).

Determine the required splice length for the epoxy-coated longitudinal bars in the following tied column made of normal-weight 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 = 28 in.Column thickness, h = 16 in.Clear cover to ties = 1.5 in.Number of longitudinal bars = 6Size of longitudinal bars = No. 8Size of ties = No. 3Concrete strength = 9,000 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 40,000 psi

Compute φVn for the cross section shown. Assume f’c = 7,000 psi, fyt = 60,000 psi, b1 = 32 in., b2 = 11 in., d1 = 7 in., d2 = 15 in., and that there are three No. 8 longitudinal tension bars and No. 4 stirrups at 10 in. o.c.

For a transformation on a reinforced concrete beam, the _______ of concrete is considered when a crack is formed. When there is no crack, the _______ of the concrete is considered.

The minimum number of longitudinal bars in a circular column is eight.