# Concrete Beam

Simple-span rectangular reinforced concrete beam, checked per ACI 318 for flexure, minimum steel, and concrete shear under a uniform gravity load (1.2D + 1.6L).

## Files

- `input.yaml` — geometry, loads, materials, and reinforcement; units are carried in the values.
- `calc.py` — computes the demands and capacities, writes `results.json`, and regenerates the cross-section figure.
- `beam_section.py` — renders the cross-section as native Typst (`assets/beam-section.typ`), drawn to a fixed schematic cover.
- `test_concrete_beam.py` — pytest checks of the demands, flexure, minimum steel, shear, reinforcement geometry, and the generated figure.
- `concrete-beam.typ` — report; compiles to `concrete-beam.pdf`.

`As` is derived from the provided bars (`n_bars`, `bar_size`).

## Usage

Edit `input.yaml`, then:

```sh
python3 calc.py                  # writes results.json and assets/beam-section.typ
python3 -m pytest                # checks the calculation and the generated figure
typst compile concrete-beam.typ  # builds concrete-beam.pdf
```

`calc.py` must be run before compiling so the figure matches the current inputs; the tests fail if `assets/beam-section.typ` is stale.

## Requirements

Python 3 with `pyyaml`, `pint`, `pytest`; Typst.