How does a beam work?
Loads on a beam cause internal forces and deformation. Supports provide reactions that must be transferred through the building. Load and support positions affect behaviour. A cantilevering beam behaves differently from a simply supported beam.
Strength and stiffness
A beam must resist the relevant forces. Its deformation must also suit the use and finishes. A floor may move uncomfortably even where strength does not govern. A design therefore involves more than one check.
Do not overlook connections
The support assumed in the calculations must match construction. A rigid connection and one assumed to be pinned are not interchangeable. Record how the beam is supported, connected and, where necessary, laterally restrained.
Practical checklist
- Identify the loads carried
- Identify the supports
- Agree material choices
- Check the connection on the drawing
Assessing a beam without its supports does not give a complete picture of the structure.
Preparing your own project
Would you like this assessed for your home? See our information about steel structures. It explains which information is relevant to that brief. The project check helps you prepare your enquiry.
Unsure about a term? The structural glossary provides plain-language explanations and technical context. To understand how the documents are organised, explore our fictional example project .
Editorial guidance • updated 2 October 2026. General information, not a project-specific assessment.