Laterally loaded pile analysis, in your browser.
The FHWA COM624P p-y finite-difference method — the same approach as LPILE and RSPile, validated against both — with every curve exposed and every input explained. No install, no dongle.
PileCalc solves the classic beam-on-nonlinear-foundation problem: EI·y'''' + Px·y'' + Epy·y = W, discretized by finite differences with the secant soil modulus iterated to convergence. Deflection, slope, moment, shear and soil reaction are reported at every node, with the governing extremes located automatically.
The p-y model library covers the published criteria engineers actually specify: Matlock (1970) soft clay, Welch & Reese (1972) and Reese-Cox-Koop (1975) stiff clay, Reese (1974) and API / O'Neill-Murchison (1983) sand, Reese (1997) weak rock, plus elastic subgrade and fully user-defined curves.
Five head boundary conditions
Shear–moment, shear–slope (fixed head), shear–rotational stiffness, deflection–moment and deflection–slope — the full COM624P set.
Layered profiles & sloping ground
Layered soils with direct or Georgiadis equivalent-depth treatment (the LPILE/RSPile approach), ground slope corrections, and a free length above grade.
Static and cyclic loading
Cyclic p-y degradation per each model's published criteria, with cycle counts where the model uses them.
Nonlinear EI and group shadowing
Cracked-section analysis via integrated moment–curvature, and p-multipliers for pile-group shadowing.
Validated against published benchmarks
Every figure below is produced by the engine on the cited published problem — closed-form solutions, design-manual tables, or independent codes — and reproduced by the test suite on every release.
COM624P / LPILE p-y finite-difference method
| Quantity | PileCalc | Reference | Agreement |
|---|---|---|---|
| Groundline deflection, long pile on constant subgrade (y₀ = 2Pβ/k)Hetényi (1946), Beams on Elastic Foundation — closed form | 0.9999 × | 1.0000 × (exact) | within 0.01% |
| Maximum moment, same case (Mₘₐₓ = 0.3224·P/β)Hetényi (1946) — closed form | 0.9998 × | 1.0000 × (exact) | within 0.02% |
| Head deflection, API-sand single layer (D 0.5 m, H 100 kN)RSPile 2018 / LPILE verification problem #1 | 7.33 mm | 7.3 mm | within 0.5% |
| Max moment, elastic pile on linear subgrade (D 1 m, L 24.4 m)Liang et al. (2014) exact series / RSPile Verification 5 | 792.2 kN·m | 792.1 kN·m | within 0.1% |
| Head moment, fixed-head pile on linear subgrade (D 1 m, L 24.4 m)Liang et al. (2014) exact series / RSPile Verification 5 | −581.1 kN·m | −581.0 kN·m | within 0.1% |
| Head deflection, elastic (Winkler) subgrade with shear + moment headIndependent-code verification example (printed output table) | 0.102107 in | 0.10210683 in | within 0.001% |
| Max moment, same elastic-subgrade caseIndependent-code verification example (printed output table) | 347,146 in·lb | 347,145.8 in·lb | within 0.001% |
| Groundline deflection, P-delta beam-column under 100 kip axial thrustIndependent-code verification example (printed output table) | 0.13171 in | 0.13172273 in | within 0.007% |
| Max moment, same P-delta caseIndependent-code verification example (printed output table) | 3,101,232 in·lb | 3,101,138 in·lb | within 0.003% |
The numbers, published
PileCalc's engine is checked term-by-term against the reference codes. A representative sample of the benchmarks — every intermediate value is visible in the app so you can reproduce them yourself.
Lateral pile analysis: common questions
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