Pressio (GBP Calculator)
Outrigger ground bearing pressure · support engineering · applied researchHow much pressure does a crane outrigger put on the ground?
The rule of thumb divides the load by the mat area. The calculator below solves what the rule ignores: mat bending and soil response. The calculation really runs, in your browser. Drag and see where the rule is wrong.
Inputs
- σ max on ground
- —kPa
- P/A rule
- —kPa
- 45° dispersion
- —kPa
- σ min (linear model)
- —kPa
- Max settlement
- —mm
- Lift-off
- —
- ΠG · Πk
- —·—
- ΠS · regime
- ——
σmax / P/A = —
—
Euler–Bernoulli beam on a Winkler–Pasternak foundation, 1D canonical case, free ends, outrigger strip load plus mat self-weight. Contact pressure p = k·w − G·w''.
ΠG = G·L0²/EmIm · Πk = k·L0⁴/EmImTwo numbers govern the response. ΠS = ΠG / 2√Πk marks the boundary between solution families: below 1, oscillatory; above, non-oscillatory.
Didactic, linear, static model, solved by finite differences on every adjustment. It does not describe failure, plasticity or transverse effects and does not replace design. Values of k and G depend on geotechnical calibration. Formulation from the paper "Mat–soil contact pressure in outrigger-stabilized cranes: the critical regimes method", by Alexandre Viana Trein and Nilson Cardoso de Lemos. [[VERIFY: published or under review? link or DOI]]
- Client and sector
- Heavy lift and outrigger support engineering. [[VERIFY: client, or in-house product]]
- Problem
- Choosing mats and outrigger support with geometric rules (P/A, 45° dispersion) that see neither mat bending nor soil response. Punch-through and settlement under outriggers are recurrent causes of serious heavy-lift incidents.
- What was done
- Django web application with a deterministic engine for preliminary mat sizing, plus an Euler–Bernoulli beam solver on a Winkler–Pasternak foundation, with lift-off handling and parametric maps in the (ΠG, Πk) plane. The calculator above is this calculation, running in your browser. [[VERIFY: development time]]
- Evidence
- Paper 1 of a series of 4 (20 pages, two authors). Solver validation run of 18 Jan 2026: 203 cases, 178 passed every criterion, 25 failed the differential-equation criterion. [[VERIFY: does the run match the current solver?]]
- Result
- [[VERIFY: use in a real project, number of analyses, mat or over-design savings]]
- What was left out
- Linear, static, 1D model. No validation against executive design and no certification. Soil parameters depend on field calibration. Research in progress: analytical solution, finite-element verification and effective support length are the next parts.
