B.3 Pressure coefficients for rectangular plan buildings
B.3.1 General
(2), (3), (4), (5) describe the use of external global and local pressure coefficients. In Diamonds you can choose between global and local by selecting the relevant tab-page.
Diamonds will apply cpe,1 when the loaded area is smaller than 1m². Diamonds uses the formula given in Figure B.1 for interpolation between cpe,1 and cpe,10.
B.3.2 Vertical walls
(4) Diamonds uses the approach in Figure B.3 c) to calculate the reference height when h>b.
The effect of this rule is clearly visible in the direction left > right (or vise versa) but not in front > back. This is because Diamonds uses a surface load generator on bars-function to determine wich bars bear which part of the surface load due to zone D. And only one value is shown for the entire bar. Thus the effect is smeared out.
(10) NOTE the provisions given in D.3.2 are not implemented in Diamonds.
(11)) NOTE2 funnelling effects between adjacent buildings can occur. The national annex can provide guidance. This is not implemented in Diamonds.
B.3.3 Flat roofs
(1) any roof with an inclination between -5° and 5° will be seen as a flat roof in Diamonds.
(6) the external local pressure coefficients from Table B.4 (NDP) are implemented in Diamonds.
Diamonds only supportes the local pressure coefficients for sharp eaves only! Even though it is possible to model parapets in Diamonds!
(7) the resulting pressure coefficient on the parapet should be determined using C.4.2. This is not implemented in Diamonds.
B.3.4 Mono pitched roofs
(10) Diamonds uses Table B.6 to determine the external global pressure coefficients. But the original value in the orange cell is not compatible with the graph in Figure B.10. We suspect a typo in the Table. Thus we adjusted the original value to the orange value in the table below.
| Pitch angle α | Zones Fup, Flow, G, H | Zone I |
| cpeg | cpeg | |
| 5° | −0,9 | −0,37 |
| 15° | −1,1 | −0,7 |
| 45° | −1,1 | −0,9 |
| 75° | −1,1 | −0,5 |
B.3.5 Duo pitched roofs
(4) Diamonds uses Table B.9 to determine the external global pressure coefficients for the direction θ=0°. But the original values in the orange cells are not compatible with the graph in Figure B.12. We suspect a typo in the Table. Thus we adjusted the original value to the orange values in the table below.
| Pitch angle α | Zones F, G, H | Zones I, J |
| cpeg | cpeg | |
| −75° | −0,5 | −0,93 |
| −60° | −0,5 | −0,85 |
| −15° | −1,0 | −0,6 |
| −5° | −0,86 | −0,6 |
| 5° | −0,73 | −0,6 |
| 0,07 | ||
| 5° ≤ α ≤ 15° | −1,0 + (α + 15°)/75° | −0,6 |
| α/75 | ||
| 15° | −0,6 | −0,6 |
| +0,2 | ||
| 15° ≤ α ≤ 30° | −1,0 + (α + 15°)/75° | −0,6 + (α − 15°)/100° |
| α/75° | ||
| 30° | −0,4 | −0,45 |
| +0,4 | ||
| 30° ≤ α ≤ 45° | −0,4 + (α − 30°)/37,5° | −0,6 + (α − 15°)/100° |
| α/75° | ||
| 45° | 0,0 | −0,3 |
| +0,6 | ||
| 75° | +0,8 | −0,3 |
(5) Diamonds uses Table B.10 to determine the external global pressure coefficients for wind from the direction θ=90°. But the original value in the orange cell is not compatible with the graph in Figure B.13. We suspect a typo in the table. Thus we adjusted the original value to the orange values in the table below.
| Pitch angle α | Zones F, G, H | Zones I, J |
| cpeg | cpeg | |
| −75° | −1,0 | −0,8 |
| −30° | −1,0 | −0,8 |
| −5° | −0,83 | −0,58 |
| 5° | −0,83 | −0,49 |
| 15° | −0,9 | −0,4 |
| 30° | −1,0 | −0,4 |
| 75° | −1,0 | −0,4 |
B.3.6 Hipped roofs
Not supported by Diamonds.
B.3.7 Multispan roofs
B.3.8 Vaulted roofs
Not supported by Diamonds.
B.3.9 Pressure on walls or roofs with more than one skin
Not supported by Diamonds.
