Concrete Wall Design: The American Concrete Institute (ACI) 318-19 is the current standard for the design of concrete structures. It includes a number of changes from the previous version, ACI 318-14, for concrete wall design. Some of the significant changes include:
- The maximum grade of reinforcement steel is now 80 ksi, up from 60 ksi in ACI 318-14.
- The minimum reinforcement ratio for walls is now 0.015 times the gross area of the wall, up from 0.012 times the gross area in ACI 318-14.
- The simplified method for shear design has been removed. The alternate simplified method is now the only method that is allowed for walls with a height-to-thickness ratio of less than 2.
- The equations for calculating the effective moment of inertia in deflection checks have been updated.
In addition to these changes, there are a number of other minor changes to the concrete wall design provisions in ACI 318-19. These changes are intended to improve the accuracy and safety of the design process.
- Maximum grade of reinforcement steel: The maximum grade of reinforcement steel is now 80 ksi, up from 60 ksi in ACI 318-14. This change is intended to allow the use of higher-strength steel, which can result in more economical designs.
- Minimum reinforcement ratio: The minimum reinforcement ratio for walls is now 0.015 times the gross area of the wall, up from 0.012 times the gross area in ACI 318-14. This change is intended to improve the ductility of walls.
- Simplified method for shear design: The simplified method for shear design has been removed. The alternate simplified method is now the only method that is allowed for walls with a height-to-thickness ratio of less than 2. This change is intended to make the shear design requirements more consistent with the requirements for other structural elements.
- Effective moment of inertia: The equations for calculating the effective moment of inertia in deflection checks have been updated. The updated equations are more accurate than the equations in ACI 318-14.
These are just some of the changes in ACI 318-19 related to concrete wall design. For more information, please refer to the code itself.
Here is an example of how to design a concrete wall according to ACI 318-19. Consider a wall with a height of 12 feet and a thickness of 8 inches. The concrete has a compressive strength of 4000 psi and the reinforcement steel has a yield strength of 60000 psi.
The first step is to calculate the required reinforcement ratio. The minimum reinforcement ratio is 0.015 times the gross area of the wall, which is 0.015 * 12 * 0.5 = 0.09. Therefore, the required reinforcement ratio is 0.09.
The next step is to calculate the amount of reinforcement required. The area of reinforcement required is the product of the reinforcement ratio and the gross area of the wall, which is 0.09 * 12 * 0.5 = 0.54 square inches.
The final step is to select the size and spacing of the reinforcement bars. The reinforcement bars should be at least No. 5 bars, and the spacing should be no more than 12 inches.
This is just a simple example of how to design a concrete wall according to ACI 318-19. The actual design process may be more complex, depending on the specific requirements of the project.