What it checks
The module designs a slender concrete wall panel for out-of-plane bending using the alternative design procedure specified in ACI 318-19 §11.8. It applies the moment magnifier method to account for P-delta effects and evaluates the section using the cracked-section stiffness defined in Eq. 11.8.3.1c. The design method is strength-based, utilizing factored loads and nominal capacities. The sequence of checks begins with verifying the applicability of the slender wall method by confirming that the axial load ratio and moment capacity meet specific thresholds. The module then calculates the stability term and moment magnifier to determine the factored mid-height moment. Finally, it compares the magnified moment against the nominal moment capacity and checks the service deflection against the allowable limit.Inputs
- Geometry - Clear height (ft), overall wall thickness (in), and effective depth (in).
- Materials - Concrete compressive strength f'c (psi) and steel yield strength fy (psi).
- Reinforcement - Bar size designator, bar spacing (in), clear cover (in), and a flag for double mat reinforcement.
- Loads - Factored axial load (kips per ft of wall width) and factored out-of-plane pressure (psf).
- Parameters - Eccentricity factor for axial load (fraction of thickness).
What it reports
- Method Applicability - A boolean indicating if all conditions in §11.8.1.1 are satisfied for the slender wall method.
- Stability Term - The calculated stability term, which must be less than 1.0 for the wall to be stable under P-delta.
- Moment Magnifier - The magnification factor derived from the stability term per §11.8.3.1(b).
- Factored Moment - The magnified factored mid-height moment (kip·ft/ft) including lateral and eccentric axial effects.
- Nominal Capacity - The nominal moment capacity Mn (kip·ft/ft) and the factored capacity phi*Mn (kip·ft/ft).
- Moment Utilization - The ratio of the factored moment to the factored nominal capacity.
- Service Deflection - The out-of-plane deflection at service (in) calculated using the bilinear stiffness model.
- Deflection Limit - The allowable deflection limit (in) based on the clear height.
- Tension Control - A boolean indicating if the section is tension-controlled based on net tensile strain.
Code references
The engine cites ACI 318-19 §11.8 for the slender wall design, specifically using the alternative method with the moment magnifier. It references Eq. 11.8.3.1c for the cracked-section stiffness and Table 22.2.2.4.3. The checks for method applicability follow §11.8.1.1, while the deflection limit is taken from ACI §11.8.4.