What it checks
The module designs a steel base plate subjected to axial load and moment. It evaluates the connection for both small and large eccentricity conditions, determining whether the load falls within the middle third of the base plate or requires a triangular stress distribution.
The design method follows AISC Design Guide 1, utilizing strength-based checks for bearing and anchor tension. The sequence of checks begins with determining the eccentricity ratio. If the eccentricity exceeds one-sixth of the axial load, the module calculates the triangular bearing length and maximum bearing stress. It then assesses the tension in the anchor rods to ensure they remain within their ultimate tensile capacity.
Inputs
- Anchor Configuration - Number of anchor rods carrying tension (integer), effective tensile stress area per rod (in²).
- Material Properties - Rod ultimate tensile strength futa (ksi), such as values for F1554 Gr36, Gr55, or Gr105.
- Load Parameters - Axial load and moment values that define the eccentricity and factored tension.
What it reports
- Eccentricity Status - A boolean flag indicating if large eccentricity governs (e > N/6).
- Bearing Length - The triangular bearing length Y (in), reported as zero when small eccentricity applies.
- Anchor Tension - Total factored anchor tension Tu (kips), reported as zero when small eccentricity applies.
- Bearing Stress - Maximum bearing stress under triangular distribution (ksi), reported as zero when small eccentricity applies.
- Anchor Demand Capacity Ratio - The DCR calculated as Tu divided by the product of rod count, phi, area, and futa.
- Anchor Adequacy - A boolean verdict indicating if anchor rods are adequate (DCR ≤ 1.0) or not required.
Code references
The engine cites AISC Design Guide 1 and ACI 318-19 §17.4.1. Specific calculations for the triangular bearing length reference DG1 §3.2. The module covers base plate bearing on concrete, plate bending cantilever lines, and anchor tension per these standards.
Limits
The module skips the anchor check if the number of tension rods is set to zero. The anchor tension DCR is reported as a maximum floating value when no rods are provided. The bearing length and anchor tension fields are set to zero when the eccentricity is small, indicating these specific large-eccentricity checks do not apply. Results are engineering aids; the engineer of record is responsible for the design.