Source: https://guthlabs.ai/docs/instruments/unit-weight-self-weight-load-calculator-structural-members/implementation/

instrument implementation / implementation-contract

# Unit Weight / Self-Weight Load Calculator (Structural Members) implementation

A source-bound implementation contract for Unit Weight / Self-Weight Load Calculator (Structural Members); deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t5-191

**Effect**: Computation or source lookup only

## Input and validation requirements

- Reject or clearly handle negative, non-finite, or missing density, weight density, area, and gravitational acceleration values.

- A zero area produces zero self-weight and should be accepted or explicitly defined as an invalid geometry boundary; negative area must be rejected.

- Do not apply g to γ because γ already includes gravitational acceleration.

- Unit mismatches, especially mm² versus m² and N/m³ versus kN/m³, can cause errors by factors of 10⁶ or 1000.

- The calculator should identify the load direction as downward and should not imply that the scalar magnitude alone fully defines a structural load.

- No division-by-zero operation is present in the stated formulas, but any later conversion or derived calculation must guard against zero denominators.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "density_rho": 7850,
    "density_unit": "kg/m³",
    "area_A": 0.01,
    "area_unit": "m²",
    "g": 9.80665,
    "g_unit": "m/s²"
  },
  "expected_outputs": {
    "w": 769.822025,
    "w_unit": "N/m",
    "w_kN_per_m": 0.769822025
  },
  "working": "w=ρ·A·g\n=7850 kg/m³ × 0.01 m² × 9.80665 m/s²\n=78.5 kg/m × 9.80665 m/s²\n=769.822025 N/m\n=0.769822025 kN/m"
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/unit-weight-self-weight-load-calculator-structural-members/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/unit-weight-self-weight-load-calculator-structural-members/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/unit-weight-self-weight-load-calculator-structural-members/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`