Calculation Methodology

Structured workflow for engineering calculation documents. Covers phases 1-5 (authoring); phase 6 hands off to calculation-report for rendering.

6-Phase Workflow

Section Reference Table

Each section has a dedicated reference file in sections/ with purpose, schema fields, required content, quality checklist, example snippet, and common mistakes.

Phase-to-Section Mapping

Phase 1 — Problem Definition

Populate sections 01 (Metadata) and 02 (Scope). Establish document control, define the calculation objective, and bound the scope with explicit inclusions, exclusions, and validity ranges. No computation occurs in this phase.

Phase 2 — Input Gathering

Populate sections 03 (Design Basis), 04 (Materials), 05 (Inputs), and 06 (Assumptions). Every input must have a traceable source. Material properties must reference certificates or code tables. Assumptions must state whether they are conservative or best-estimate and justify why.

Phase 3 — Method Selection

Populate section 07 (Methodology). Select the governing standard and edition. Confirm applicability to the problem geometry, load regime, and material. Present equations in symbolic form before substituting numeric values.

Phase 4 — Computation

Populate sections 08 (Calculations) and 09 (Outputs). Execute the method step-by-step with clause references at each step. Record intermediate results with units. Summarize results with pass/fail status and utilization ratios.

Phase 5 — Validation

Populate sections 10 (Sensitivity), 11 (Validation), 12 (Verification), and 13 (Conclusions). Perform sensitivity sweeps on key parameters. Validate against benchmarks or alternative methods. Record independent check details. State the adequacy conclusion with governing check identification.

Phase 6 — Reporting

Populate sections 14 (Charts), 15 (Data Tables), and 16 (References). Finalize visualizations and citation list. Then trigger the calculation-report skill to render the structured YAML into HTML/PDF output.

Handoff to calculation-report:

# After all sections are populated:
# 1. Validate YAML structure against schema
# 2. Invoke calculation-report skill with the calc YAML path
# 3. Review rendered output for formatting issues

Quality Checklist — Commonly Missed Items

These items are the most frequent causes of calculation rejection in engineering review, drawn from EFCOG, DNV, Structures Centre, and Caltrans guidance:

Problem Definition (Phase 1)

• Calculation objective states what is being proved, not just what is computed
• Exclusions are explicit — reviewers should not guess what is out of scope
• Validity range specifies temperature, pressure, and geometry limits

Input Gathering (Phase 2)

• Every input has a source reference (not just a value)
• Units are consistent throughout — no mid-calculation unit changes
• Material partial safety factors match the code edition cited
• Assumptions are numbered and each has a justification sentence

Method Selection (Phase 3)

• Standard edition year is stated (not just the standard number)
• Applicability limits of the method are checked against actual parameters
• Equations appear in symbolic form before numeric substitution

Computation (Phase 4)

• Each calculation step cites the specific clause or equation number
• Intermediate results are shown (not just final answers)
• Hand-check or order-of-magnitude sanity check is present

Validation (Phase 5)

• At least one independent validation method is used
• Sensitivity analysis covers the top 3 most uncertain parameters
• Verification record includes checker name and date
• Conclusion explicitly states which check governs the design

Reporting (Phase 6)

• All referenced standards appear in the reference list with edition
• Charts have axis labels, units, and titles
• Data tables state units in column headers, not in cell values

Usage

# Typical invocation pattern:
# 1. Agent loads this skill when a calculation task is identified
# 2. Work through phases 1-5, populating section YAML
# 3. At phase 6, hand off to calculation-report for rendering
#
# For section-specific guidance, read the relevant file:
#   .claude/skills/engineering/calculation-methodology/sections/01-metadata.md

Research Sources

This skill synthesizes calculation documentation best practices from:

• EFCOG (Energy Facility Contractors Group) — calculation note guidance
• DNV (Det Norske Veritas) — recommended practices for documentation
• Structures Centre — structural calculation note templates
• Eng-Tips — practitioner discussions on calculation quality
• Caltrans — bridge design calculation documentation standards