A depressed arch is an arch whose rise (height) is small relative to its span, making it much flatter than a semicircular arch. The ratio between height and width determines how “depressed” the arch appears.
Features
A depressed arch comes in several forms, depending on the curvature used.
- Segmental arch: a portion of a circle with a shallow curve
- Basket arch: made up of several circular arcs with different radii
- Elliptical arch: based on an ellipse
- Low rise-to-span ratio, giving a flat appearance
The main drawback of a depressed arch is that it generates greater horizontal thrust on the supports. The arch pushes outward more strongly than a semicircular arch, so heavier resistance is required in the form of buttresses or sturdy abutments.
Application
The depressed arch is mainly used where little building height is available.
- Wide wall openings where a tall arch will not fit
- Bridges with a low clearance height
- Doors and windows with limited height above the opening
- Spans where a flat, clean appearance is desired
Related terms
- Arch
- Basket arch
- Segmental arch
- Lintel
- Buttress
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