Shear stresses will exist in those parts of a beam where the moment is constant from section to section.

A 123-mm-long beam supports a load of P = 40 N at midspan. The cross section is rectangular with width b = 29 mm and height h = 60 mm. Determine the magnitude of the horizontal shear stress at the centroid of the cross section.

Compute φVn for the cross section shown. Assume f’c = 4,000 psi, fyt = 60,000 psi, b = 14 in., d = 23 in., and that there are four No. 7 longitudinal tension bars and No. 4 stirrups at 9 in. o.c.

Assuming Vs exceeds 4sqrt(f’c)bwd, the maximum spacing for vertical stirrups in the following beam is _____. Let b = 13 in. and d = 61 in. There are four No. 9 longitudinal tension bars and No. 3 stirrups at 6 in. o.c.

If φVc = 43 kip and Vu = 54 kip, are stirrups required?

Compute φVn for the cross section shown. Assume f’c = 4,000 psi, fyt = 40,000 psi, d = 22 in., w = 16.5 in., t = 4 in., and that there are four No. 8 longitudinal tension bars and No. 3 stirrups at 6 in. o.c.

A continuous beam’s flexural reinforcement must extend at least _____ from the point where it is no longer needed to resist tension. Assume f’c = 4,000 psi, fyt = 40,000 psi, d = 30 in., w = 20.5 in., and t = 6 in. There are five No. 6 longitudinal tension bars and No. 5 stirrups at 7 in. o.c.

If φVc = 27 kip and Vu = 56 kip, are stirrups required?

A beam has dimensions of b = 18 in., h = 24 in., and d = 21.5 in. and is reinforced with 2 No. 6 bars. The concrete strength is 9,400 psi, and the yield strength of the reinforcement is 60,000 psi. Determine the strength Mn for this beam.

When faced with severe architectural restrictions on the dimensions of a beam, a designer may be forced to use a doubly reinforced section.