Sections 7.7.2.2 and 9.7.2.2 Reinforcement Spacing Limits for Class C Members

See Sections 7.7.2.2 and 9.7.2.2 Minimum Reinforcement of Flexural Members (Non Prestressed) .

The following procedure is used to determine the maximum bar spacing:

The maximum fs in the cross section is determined, including all bonded tendons in the tension zone and all bar positions.
For bonded PT in tension zone, an effectively reinforced width is calculated:
$w_{i} = \min (\begin{matrix} \frac{600, 000}{max f_{s}} - 2.5 cci \\ \frac{480, 000}{max f_{s}} \end{matrix}) \frac{2}{3} NumberOfDucts$
This width is subtracted from the total tension face width, and the rebar spacing is calculated using the remaining width.
A stress limit is calculated using re- arranged equation for deformed bars and wires (Table 24.3.2) and compared with the fs calculated in the first step.
Rebar is added and all steps are repeated until fs is within the calculated stress limit.

If tendons are used to reduce the required tension face reinforcement width, the tendon Δfps will be limited to 36 ksi in accordance with 24.3.2.2. Rebar will be added until this limit is met.

If any tendon w_i or any required bar spacing is negative the bar or tendon is deemed ineffective for controlling crack width and is ignored.

In the unusual circumstance where no bars or tendons are in the tension zone, no rebar will be added.