Reinforcement Spacing Limits
This section discusses the spacing limit checks that are implemented within the RAM Concrete Wall module and the assumptions made by the program when performing the necessary checks. The table provides a summary of the sections of ACI 318-11 covering spacing limits that have been implemented within the program.
| Code Section | Limit Check | Referenced Code Sections |
|---|---|---|
| 7.6.1 | Minimum clear bar spacing | - |
| 7.6.5 | Maximum bar spacing in walls | - |
| 14.3.1 | Maximum spacing of horizontal shear reinforcement in walls | 11.9.9.3, 11.9.9.5 |
| 14.3.5 | Maximum spacing of vertical shear reinforcement in walls | - |
| 7.10.5.2 | Maximum vertical spacing of ties in walls | - |
| 21.9.2.1 | Maximum reinforcement spacing in walls | - |
When checking maximum spacing limits, the RAM Concrete Wall module uses the nominal reinforcement spacing; that is, the spacing identified in the Bar Pattern. When checking minimum spacing limits, the RAM Concrete Wall module uses the true reinforcement spacing considering the way the bars have been placed by the program. This is done so that the most appropriate value of spacing is used in comparison to each code prescribed limiting value.
It is important to note that when spacing checks are performed for a Section Cut, only the bars normal to the Section Cut will be evaluated for spacing compliance. Thus, in order to check horizontal bars for compliance in a Wall Panel it is necessary to include at least one vertical Section Cut that intersects the Wall Panel.
Chapter 7
Section 7.6 of ACI 318-11 specifies spacing limits for reinforcement. The RAM Concrete Wall module checks ACI Sections 7.6.1 and 7.6.5 within ACI 7.6. The design process will produce failures if the Bar Pattern or Manual Reinforcement used for a Wall Panel results in bar spacings that violate either of these limits.
For ACI Section 7.6.5, the wall thickness used for the check is the gross section thickness of the Wall Panel to which the Bar Pattern or Manual Reinforcement has been assigned. Since each Wall Panel is a constant thickness entity, and each Wall Panel has only a single Bar Pattern, there is no ambiguity as to the appropriate value of thickness to use in this calculation.
Chapter 14
The RAM Concrete Wall module checks Section 14.3.1 of ACI 318-11, which specifies the minimum horizontal and vertical reinforcement in walls. This section mandates that the spacing of horizontal and vertical shear reinforcement in walls complies with ACI Sections 11.9.9.3 and 11.9.9.5, respectively.
Each of the Wall Panels that intersect the Section Cut is checked separately for these provisions using the respective Wall Panel gross section thickness and Bar Pattern. The parameter lw in 11.9.9.3 and 11.9.9.5 is taken as the length of the Wall Panel, and the parameter h is taken as the average height of the Wall Panel. For example, for the Wall Panel shown in Figure below, lw = 25’ and h = 14’. If the Wall Panel has a sloping top and/or bottom edge, the average of the heights at the start and end of the Wall Panel is used for h.
The module also considers Section 14.3.5 of ACI 318-11.