Learning objectives
In this lesson
- A spectrum summarizes peak oscillator response by period.
- Corner periods mark shape transitions.
Engineering explanation
A response spectrum plots peak response of idealized single-degree-of-freedom oscillators exposed to a defined motion. Each point represents a natural period; the curve is not a time history and its peaks do not occur simultaneously. Short-, intermediate- and long-period regions express different response characteristics, while corner periods mark transitions in the prescribed shape. Damping assumptions and vertical components must follow the applicable source. This lesson intentionally provides no unverified numerical spectrum definition.
Concept exercise
Concept diagram: response-spectrum regions
Trace a hypothetical natural period to its spectral ordinate. Do not infer project values.
Short-period region
Stiff systems may attract high acceleration.
Intermediate region
The prescribed shape commonly contains a high-demand transition or plateau.
Long-period region
Flexible systems shift interpretation toward displacement-sensitive response.
Key takeaways
What to carry forward
- A spectrum summarizes peak oscillator response by period.
- Corner periods mark shape transitions.
- Damping and vertical-action rules are source-dependent.