LAYER 26 Zone A
Zone B
The weight of the layers of the column from layer 15 - 26 is added to the self-weight of the chair in Zone A calculated in the previous section. Combined with the weight of the person distributed within Zone A, the bearing on this layer of the column is determined.
The weight of layers 15 to 25 are added to the previously determined self-weight to determine the total bearing in Zone B onto the outer ring of layer 26.
Zone ALayer 15 = 24 966 mm AColumn = 9 130 mm2 2
P(layers 16-25)
[from AutoCAD file]
= (9 130 mm2 x 4.1x10-6 kg/mm2 x 9.8 m/s2 ) 10 layers = 0.37 N x 10 layers = 3.7 N
Zone BCLayer15-25= 828 268 mm2 P(layers 15-25)
= 828 268 mm2 x 4.1x10-6 kg/mm2 x 9.8 m/s2 = 33.2 N PZone B = 33.2 N + 29.1 N = 62.4 N
P(layers 15)
Zone BCLayer26 = 68 054 mm2
P(layers 1-14)
= 9.27 N
FC
Pperson
= 588 N (Zone A15/ Zone AC15) = 588 N (24 966 mm2 / 42 342 mm2 ) = 588 N (0.5896) = 346 N
= 24 966 mm2 x 4.1x10-6 kg/mm2 x 9.8 m/s2 = 1.0 N
PZone A = 3.7 N + 1.0 N + 9.27N + 346 N = 360 N FC =P/A = 360 N / 9 130 mm2 = 0.0394 MPa = 39.4 kPa Comparing this to the allowable bearing stress for plywood, the member is found more than adequate in compression. 2 340 kPa >> 39.4 kPa
[from AutoCAD file]
=P/A = 62.4 N / 68 054 mm2 = 9.16 x 10-4 MPa = 916 Pa