Footing Size Calculator (Preliminary)

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Mechanical, Civil & Structural Engineering — Statics/Dynamics, Strength of Materials, Machine Design, Civil, HVAC, Vibration

Tranche

tranche-5

Evidence ID

t5-131

Ledger rows

1

No ledger note is attached.

Review findings

The algebra is correct for preliminary sizing under a centered axial load, positive allowable pressure, compatible units, and a square footing assumption. Verdict is NEEDS_REVIEW because the specification leaves the load basis, gross-versus-net pressure convention, unit contract, and applicability constraints ambiguous. The existing honest label is appropriate but should explicitly state that self-weight, eccentricity/moments, settlement, shear, stability, code minimums, and constructible rounding are excluded.

Formula and scope findings

• A_req=P/qallow is the standard preliminary formula only for a concentric axial load and a uniformly distributed allowable bearing pressure; the specification does not state those constraints.
• The formula does not account for footing self-weight, overburden, eccentricity, moment, shear, settlement, sliding, overturning, or code-required minimum dimensions and rounding.
• The square-footing dimension formula is valid only when a square plan shape is explicitly selected; rectangular footing dimensions are not determined by the provided formulas.

Unit assumptions

• P and qallow must use compatible force units, with qallow expressed as force per unit area.
• Examples using kN and kPa rely on 1 kPa=1 kN/m², so P/qallow produces m².
• Examples using N and kPa require converting qallow from kPa to N/m² before division.
• The calculation assumes P is the load basis appropriate for comparison with the stated allowable soil pressure, but the specification does not identify whether P is service, factored, net, or gross load.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The plain formula has no stated input validation or load-sign convention. Zero or negative allowable pressure can cause division-by-zero or invalid negative areas, zero load produces a nonphysical zero footing, and a signed compressive load can produce an undefined square root.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "P": 600,
    "P_unit": "kN",
    "qallow": 200,
    "qallow_unit": "kPa",
    "shape": "square"
  },
  "expected_outputs": {
    "required_area": 3,
    "required_area_unit": "m²",
    "square_side": 1.73205,
    "square_side_unit": "m"
  },
  "working": "1. Since 1 kPa=1 kN/m², qallow=200 kN/m². 2. A_req=P/qallow=600 kN ÷ 200 kN/m²=3 m². 3. Square side=√A_req=√3 m=1.73205 m."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json