Due to Poisson’s ratio, the diameter of the reinforcing bar decreases as it is loaded in tension and both the bond the adhesion and the friction between it and the concrete are lost.

For economy, some of the bars can be terminated or cutoff where they are no longer needed.

Compression-development lengths are considerably longer than tension-development lengths, because some force is transferred to the concrete by the bearing at the end of the bar.

In a pull-out test, a concrete cylinder containing the bar is placed on a stiff plate and a jack is used to pull the bar out of the cylinder.

Use ACI 318-14 Table 25.4.2.2 to determine the development length for the straight tension bars (no hooks) in a rectangular beam with b = 18 in. and d = 23 in., four uncoated No. 8 Grade 60 bars placed in the bottom of the beam, and No. 4 Grade 40 stirrups located every 8 in. along the span. Assume 7,000-psi normal-weight concrete and a clear cover of 1.5 in.

Assuming Vs does not exceed 4sqrt(f’c)bwd, the maximum spacing for vertical stirrups in the following beam is _____. Let b1 = 21 in., b2 = 10 in., d = 39 in., h1 = 6 in., h2 = 29 in., h3 = 9 in., and t = 6 in. There are six No. 7 longitudinal tension bars and No. 4 stirrups at 9 in. o.c.

Determine the transverse reinforcement index, Ktr, for a rectangular beam with b = 16 in. and d = 24 in., four epoxy-coated No. 9 Grade 60 tension-reinforcement bars placed in the bottom of the beam, and No. 4 Grade 60 stirrups located every 12 in. along the span. Assume 4,000-psi normal-weight concrete and a clear cover of 2 in.

In a pull-out test, a concrete cylinder containing the bar is placed on a stiff plate and a jack is used to pull the bar out of the cylinder.

Which type of reinforcement is frequently used in bridge decks?

A rectangular beam with cross section b = 16 in., h = 26 in., and d = 23.5 in. supports a total factored uniform load of 1.10 kips/ft, including its own dead load. The beam is simply supported with a 24-ft span. It is reinforced with five No. 5 Grade 60 bars, three of which are cutoff between midspan and the support and two of which extend 10 in. past the centers of the supports. The concrete strength is 3,000 psi (normal weight). The beam has Grade 60 No. 3 stirrups satisfying ACI 318-14 Sections 9.7.6.2.2 and 9.6.3.3. The strength of the five bars is φMn = 156 kip-ft, and the strength of the remaining two bars is φMn = 64.29 kip-ft. If the distance from the support to the theoretical cutoff point is 6.793 ft, determine the distance from the support to the actual cutoff point (i.e. use ACI 318-14 Section 9.7.3.3).