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7c60059 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 | # RecrBeam Calculator
[](https://www.python.org/)
[](https://opensource.org/licenses/MIT)
[](https://www.concrete.org/)
[](https://github.com/TomSchimansky/CustomTkinter)
A professional desktop application for calculating the **Nominal Moment Strength (Mn)** of rectangular reinforced concrete beams per ACI 318 provisions.
## Features
- Native Windows desktop application (no browser/localhost required)
- Professional dark theme UI
- Real-time calculations as you type
- **Unit system toggle**: Imperial (psi, in) / SI (MPa, mm)
- **Visual diagrams**: Cross Section, Strain Distribution, Stress Block & Forces
- **Step-by-step equations**: Detailed calculation breakdown with OK/NG indicators
- Minimum steel area check per ACI 318
## Installation
### Prerequisites
- Python 3.9 or higher
- pip (Python package manager)
### Setup
1. **Clone the repository**
```bash
git clone https://github.com/algorembrant/RecrBeam-Calculator.git
cd RecrBeam-Calculator
```
2. **Create a virtual environment** (recommended)
```bash
python -m venv .venv
```
3. **Activate the virtual environment**
Windows (PowerShell):
```powershell
.\.venv\Scripts\Activate.ps1
```
Windows (Command Prompt):
```cmd
.venv\Scripts\activate.bat
```
macOS/Linux:
```bash
source .venv/bin/activate
```
4. **Install dependencies**
```bash
pip install -r requirements.txt
```
## Usage
### Run the Application
```bash
python app.py
```
The application will launch as a native desktop window.
### Input Parameters
| Parameter | Description | Imperial | SI |
|-----------|-------------|----------|-----|
| fc' | Concrete compressive strength | psi | MPa |
| fy | Steel yield strength | psi | MPa |
| Es | Modulus of elasticity | psi | MPa |
| Beta1 | Stress block factor | - | - |
| ecu | Ultimate concrete strain | - | - |
| b | Beam width | in | mm |
| h | Total beam depth | in | mm |
| d | Effective depth | in | mm |
| n | Number of bars | - | - |
| Ab | Bar area (each) | in2 | mm2 |
### Default Values (Example 4-1)
**Imperial:**
- fc' = 4000 psi, fy = 60,000 psi
- b = 12 in, h = 20 in, d = 17.5 in
- 4 bars at 0.79 in2 each (No. 8 bars)
**SI:**
- fc' = 20 MPa, fy = 420 MPa
- b = 250 mm, h = 565 mm, d = 500 mm
- 3 bars at 510 mm2 each
## Project Structure
```
RecrBeam-Calculator/
├── app.py # Main desktop application (CustomTkinter)
├── calculator.py # Beam calculation engine
├── test_calculator.py # Unit tests
├── requirements.txt # Python dependencies
├── README.md # This file
├── LICENSE # MIT License
├── MATLAB/
│ └── app.m # Original MATLAB implementation
└── Dump/
└── example_4_1.tex # LaTeX documentation
```
## Theory
Based on ACI 318 provisions for nominal moment strength:
### Key Equations
**Stress block depth:**
```
a = (As * fy) / (0.85 * fc' * b)
```
**Neutral axis depth:**
```
c = a / Beta1
```
**Nominal moment strength:**
```
Mn = As * fy * (d - a/2)
```
**Minimum steel area (Imperial):**
```
As,min = max(3*sqrt(fc')/fy * b*d, 200/fy * b*d)
```
## Running Tests
```bash
python -m unittest test_calculator -v
```
## Dependencies
- [CustomTkinter](https://github.com/TomSchimansky/CustomTkinter) - Modern UI framework
- [Matplotlib](https://matplotlib.org/) - Diagram plotting
- [NumPy](https://numpy.org/) - Numerical operations
## License
MIT License - see [LICENSE](LICENSE)
## References
- ACI 318-19: Building Code Requirements for Structural Concrete
- Example 4-1 and 4-1M from ACI 318 Design Handbook
## Citation
If you use this software in your research or project, please cite it as:
```bibtex
@software{recrbeam_calculator,
author = {algorembrant},
title = {RecrBeam Calculator: Nominal Moment Strength Calculator for Rectangular Beams},
year = {2026},
publisher = {GitHub},
url = {https://github.com/algorembrant/RecrBeam-Calculator},
note = {Based on ACI 318 provisions}
}
```
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