Braced construction is a structural system that resists horizontal loads through separate stabilising elements such as diagonal bracing or a stiff core, whereas unbraced construction relies on rigid moment connections between beams and columns for its stability.
Every building must resist not only vertical loads but also horizontal forces from wind, imperfections and, in some regions, earthquakes. The way this lateral stability is provided defines whether a frame is braced or unbraced.
The two systems
- Braced: stability comes from diagonal braces, shear walls or a stiff core. Beam-to-column joints can be simple pinned connections.
- Unbraced: stability comes from stiff, moment-resisting joints between beams and columns, so the frame itself resists sway.
Application
The choice affects layout, cost and connection design.
| Aspect | Braced | Unbraced |
|---|---|---|
| Lateral stability | Bracing or core | Rigid joints |
| Connections | Simple, pinned | Moment-resisting |
| Open floor plan | Bracing may obstruct | Fully open possible |
Braced frames are efficient and economical but the bracing can limit openings and layout. Unbraced frames keep the plan open but require heavier members and more complex connections. Many buildings combine both approaches, using a braced core with otherwise flexible framing.
Related terms
- bracing
- stability
- structure
- column
- truss
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