Working with Curved Forms
The Washington State History Museum in Tacoma, USA, is a visually powerful example of the bending strength of APA Plyform. Curved forms were integral to achieving the architectural design – and were used to form its eleven concrete arches, each 55ft. high.
APA Plyform is stronger than conventional plywood, with an exterior bond classification. See APA’s Concrete Forming Design/Construction Guide. The tighter the radius of curvature, the thinner the plywood needs to be to bend to the required shape.
The table below provides the minimum radii to enable APA Plyform panels to be bent while dry. Tighter radii can be developed by special selection of panels or by wetting or steaming them.
|
Minimum Bending Radii for APA Plyform panels – these values are based on the physical properties of non-overlaid Douglas fir |
|||||
|---|---|---|---|---|---|
|
Panel sizing in inches and mm |
Across The Grain |
Parallel to The Grain |
|||
| Panel Performance Category
|
Equivalent Thickness in mm |
ft. |
mm |
ft. |
mm |
|
1/4 5/16 3/8 1/2 5/8 3/4 |
6.4 7.9 9.5 12.7 15.9 19.1 |
2 2 3 6 8 12 |
0.610 0.610 0.915 1.828 2.438 3.658 |
5 6 8 12 16 20 |
1.524 1.828 2.438 3.658 4.877 6.096 |