What it checks
The module designs a CMU pilaster, defined as the thickened column inside a masonry wall that takes wall reactions, axial load, and out-of-plane moment together. It evaluates the member under combined loading conditions using the specified masonry compressive strength and steel yield strength.
The design method applies strength-based checks using factored loads and resistance factors. The sequence of checks implied by the inputs involves assessing the member's capacity against the factored axial load, factored uniaxial moment acting about the weak axis, and factored shear. The module accounts for the effective length factor to adjust for end conditions in the stability assessment.
Inputs
- Geometry - Nominal pilaster width parallel to the wall (inches), nominal pilaster depth perpendicular to the wall (inches), and unbraced or effective height (feet).
- Stability - Effective length factor k, with values corresponding to pin-pin, fix-pin, or fix-fix end conditions.
- Materials - Specified masonry compressive strength f'm (psi) and steel yield strength fy (psi).
- Reinforcement - Rebar size number, number of vertical bars, and approximate bar placement distance from face to bar centroid (inches).
- Loads - Factored axial load Pu (kips), factored uniaxial moment Mu (kip·ft) acting about the weak axis, and factored shear Vu (kips).
- Factors - Resistance factor phi for axial and flexure, and phi_shear for shear.
What it reports
- Axial Capacity - The module evaluates the member's resistance to the factored axial load Pu, comparing it against the calculated capacity using the specified phi factor.
- Flexural Capacity - The module assesses the resistance to the factored uniaxial moment Mu, which acts about the weak axis of the pilaster, using the specified phi factor.
- Shear Capacity - The module checks the resistance to the factored shear Vu, comparing it against the calculated capacity using the specified phi_shear factor.
- Combined Loading - The results reflect the interaction of axial load, moment, and shear, ensuring the pilaster can sustain the simultaneous demands of wall reactions and out-of-plane forces.
- Stability Adjustment - The effective length factor k is applied to the unbraced height to determine the effective length used in the stability checks.
Code references
The engine cites TMS 402-22 §9.3 for pilaster design. It also references TMS §9.1.4.1 for the resistance factors phi for axial and flexure, and phi_shear for shear. The bar area lookup utilizes ASTM A615 nominal bar area values from the SHAPE database.
Limits
The module assumes the moment acts about the weak axis of the pilaster, specifically bending in the plane of the wall about the b dimension. It does not account for biaxial bending or moments about the strong axis. The bar area lookup relies on a local table for #3–#11 bars with a 0.20 fallback value. Results are engineering aids; the engineer of record is responsible for the design.