Building an Interactive I-Beam Dimensions Diagram with HTML, CSS & JavaScript

Beamchart — Sat, 19 Sep 2026 20:30:36 +0000

Engineering diagrams don't always need complex libraries or expensive visualization software.

Sometimes, HTML, CSS, SVG, and a little JavaScript are enough to turn a static technical illustration into an interactive learning resource.

In this tutorial, we'll explore how to build an interactive steel I-beam cross-section that helps users understand four important dimensions:

Overall depth (d)
Flange width (bf)
Web thickness (tw)
Flange thickness (tf)

The goal is to create a lightweight, responsive visualization that works across desktop and mobile devices.

Why Use SVG?

SVG is useful for technical diagrams because it remains sharp at different screen sizes and allows individual elements to be styled and controlled with JavaScript.

For this project, we'll use SVG to represent the beam cross-section and illustrate its dimensional measurements.

Each dimension will have an interactive control that displays its corresponding explanation.

How the Interaction Works

We'll create a simple JavaScript object containing information about each dimension.

When a user selects a measurement, JavaScript will:

Identify the selected dimension.
Highlight the corresponding measurement in the diagram.
Update the title and explanation.
Update the active button state.

The result is an educational tool that makes technical terminology easier to explore.

Building the Diagram

The project uses three technologies:

HTML: Provides the page structure and dimension controls.

CSS: Handles the responsive layout, typography, colors, and active states.

JavaScript: Controls the interactive behavior.

Insert the complete working code and a live CodePen demonstration here before publishing.

Explore the Full Steel Beam Reference

This diagram illustrates the terminology used in structural steel reference tables.

For actual steel beam sizes, dimensions, weights, section properties, and weight calculations, explore BeamChart.

The website provides structural steel reference information based on AISC Shapes Database v16.0.

Final Thoughts

Interactive diagrams are a practical way to make complex technical information easier to understand.

By combining SVG with straightforward JavaScript, developers can build useful educational tools without introducing unnecessary dependencies.