ConcreteDesignPy

A Python library and web application for reinforced concrete structural design per NSCP 2015 and ACI 318-19.

Disclaimer: This is an internal tool for Albert Pamonag Engineering Consultancy (APEC). All results must be verified by a licensed professional engineer. The developers assume no liability for errors or misuse.

Features

Beam Design

• Flexural Capacity — Strain compatibility method with iterative neutral axis solver, strength reduction factor (phi) plot per ACI 318-19 Table 21.2.2
• Shear Strength — Concrete and steel shear capacity, stirrup spacing design with Excel export (ACI 318M-14)
• Torsion Design — Combined shear-torsion interaction checks
• Deflection — Immediate and long-term deflection with effective moment of inertia

Column Design

• P-M Interaction — Strain compatibility analysis with Plotly interaction diagrams, load combination overlay
• Minimum Flexural Strength — Column-to-beam strength ratio verification

Analysis Tools

• Moment-Curvature — Dual-mode M-phi analysis:
  • Quick (6-Point) — Closed-form key points (cracking, yield, ultimate) per ACI 318-19
  • Advanced (Incremental) — Hognestad parabolic concrete model with fiber-layer approach, axial load support, 60-point smooth curve
• Mander Confined Concrete — Full Mander, Priestley & Park (1988) model with 13-step transparent report, biaxial confinement (Fig. 5), Plotly stress-strain curves, and confinement effectiveness charts
• Joint Shear — Verification for special moment frames (Section 422.7)

Detailing

• Development Length — Hook geometry for deformed bars and stirrups (Section 425)
• Alternative Inertia — Effective moment of inertia per Section 424.2.3.5

Web Application

• Flask-based interactive calculators
• Plotly charts for all visualizations (M-phi diagrams, P-M interaction, stress-strain curves, section analysis)
• MathJax-rendered calculation reports with full formula substitution
• Print-ready output with engineering notation

Installation

pip install -e .

Dependencies

• Python 3.8+
• Flask
• NumPy
• Gunicorn (production)
• openpyxl

Running Locally

python run.py

Then open http://localhost:5000 in your browser.

Project Structure

concretedesignpy/
├── calculators/          # Backend calculation modules
│   ├── beam_moment.py    # Flexural capacity (neutral axis solver)
│   ├── beam_shear.py     # Concrete & steel shear strength
│   ├── beam_torsion.py   # Torsion design checks
│   ├── beam_deflection.py
│   ├── column_interaction.py  # P-M interaction diagram
│   ├── column_flexural.py     # Min flexural strength ratio
│   ├── joint_shear.py
│   ├── mander.py              # Confined concrete model
│   ├── moment_curvature.py    # M-phi analysis
│   ├── development_length.py  # Hook geometry
│   ├── alternative_inertia.py
│   ├── rebar_layout.py        # Section rebar coordinates
│   └── diagrams.py            # SVG diagram generators
├── webapp/
│   ├── app.py            # Flask application factory
│   ├── routes/           # API endpoints (beam, column, section, joint, mander)
│   ├── templates/        # Jinja2 HTML templates with MathJax
│   └── static/           # CSS & JavaScript
├── Procfile              # Railway/Heroku deployment
├── railway.json          # Railway config
├── requirements.txt      # Python dependencies
└── setup.py              # Package setup

API Endpoints

See the Wiki — API Reference for the full list of 17 POST endpoints.

Code Standards & References

• NSCP 2015 — National Structural Code of the Philippines
• ACI 318-19 / ACI 318M-14 — American Concrete Institute
• ACI SP-17 — Design Handbook
• Mander, Priestley & Park (1988) — Theoretical stress-strain model for confined concrete, J. Structural Engineering, ASCE, Vol. 114, No. 8
• Hognestad (1951) — A study of combined bending and axial load in reinforced concrete members, University of Illinois Bulletin No. 399

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature-name)
3. Commit your changes
4. Submit a pull request

License

MIT License. See LICENSE for details.