CB

Circular Base Plate — Large Eccentric Loads (Interactive Calculator)

Implements the step-by-step procedure from your uploaded PDF (Procedure for the Analysis and Design of Circular Base plates with Large Eccentric Loads). See note at the end about assumptions and limitations. File referenced: uploaded PDF.

Inputs (Applied loads & plate/bolt geometry)

Vertical load, P (kN) Bending moment about x (kN·m) — use same axis as eccentricity Allowable bearing stress, F_p (kPa)

Plate diameter, N (mm) Number of anchor bolts (total) Bolt circle diameter (BCD) (mm)

Column centreline offset (A') — distance from column centreline to CG of tensile bolt group (mm). If left blank, computed automatically for symmetric half-circle tensile group.

If bolts are uniformly placed on a bolt circle and only bolts on the tension side react (conservative), the tool assumes bolts lying in the half-circle opposite the compressive segment. You can override A' above.

Trial / solver settings

Trial segment height, h (mm) — chord-to-arc height of bearing segment. (Or leave blank and use Auto-solve) Stopping tolerance for auto-solver (mm)

Allowable tensile capacity per bolt (kN) Max iterations for auto-solver

Results

Plate radius, R (mm)
Segment height, h (mm)
Central angle, θ (deg)
Segment area, Aseg (mm²)
Segment area, Aseg (m²)
Centroid of segment from chord (distance ychord) (mm)
Centroid of segment from circle center (mm) — towards arc
Resultant compression, Rc = Fp × Aseg (kN)
Total bolt tensile resultant, T = P − Rc (kN)
Computed A' used (mm)
Moment equilibrium check: Rc × xc vs T × A' (kN·mm)
Max bolt tension, Tmax (kN)
Allowable per bolt (kN)
Pass / Fail tensile check

Bolt tension distribution (list of bolts on tension side)

Notes: This tool follows the PDF procedure (uploaded file) to compute segment geometry and resultant compression, then derives bolt tensions assuming linear strain → tension variation with radial position. The auto-solver attempts to find the segment height h that satisfies moment equilibrium (Rc * x_c = T * A'). See endnotes for assumptions and recommended checks.

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Endnotes — assumptions, units & limitations

• This tool implements the circular segment geometry formulas (area and centroid) using standard relations: θ = 2 acos((R−h)/R), A = (R²/2)(θ − sin θ), centroid from center y = (4 R sin³(θ/2)) / (3(θ − sin θ)). These are the standard formulas used to evaluate the shaded compressive segment in the PDF.
• Units: P input in kN (converted to N), M in kN·m (converted to N·mm), N and h in mm. Fp is requested in kPa (kN/m²): conversion to N/mm² is done internally by multiplying by 1e-3.
• The auto-solver finds the segment height h that attempts to satisfy the moment equilibrium Rc * x_c = T * A'. A' is either user-entered or computed as the centroid of the tensile bolt group assuming bolts on a uniform bolt circle and that only bolts lying on the tension side (opposite the compressive segment) take tension (conservative). This mirrors the conservative approach in the PDF (anchor bolts in only one half of the circle considered).
• The bolt tension distribution uses a simple proportional rule: tension ∝ distance from neutral chord line (linear strain assumption). The PDF describes Tmax calculation from linear strain distribution; this tool implements a practical distributed approach consistent with that assumption. For rigorous professional design, use a full equilibrium/sectional analysis and check against code recommendations and anchorage details.
• Results must be validated against your code/standard (AISC, IS, or local design practice). This web tool provides engineering-level numeric assistance and follows the step sequence given in your PDF, but your project may require additional checks (anchorage capacity, shear, load combinations, fatigue, plate bending checks per eqn. 8/9/10 references in the PDF, and plate thickness design eqn referencing M_pl, F_b, etc.).
• If you want, I can (a) add explicit plate thickness calculation (use eqn. in your PDF, include bending moment per unit width Mpl and Fb), (b) allow arbitrary bolt coordinates to be entered, or (c) change Fp units to N/mm² directly. Tell me which extension you want and I will add it directly into this same HTML file.