Table 4 Tephra sliding coefficients for monopitch and simply pitched roofs
From: Laboratory tests to understand tephra sliding behaviour on roofs
Roof type | Tephra type | Low pitch | Medium pitch | Steep pitch | Equation | |
|---|---|---|---|---|---|---|
Monopitch or simply pitched, with pitch = α
| Coarse-grained (Pumice or scoria) | α ≤ 15° µcoarse = 1 | 15° < α < 35° µcoarse = (35 – α)/20 | 35° ≤ α µcoarse = 0 | (1) | |
Fine-grained (Ash) | α ≤ 20° µfine = 1 | 20° < α < 35° µfine = (35 – α)/15 | 35° ≤ α µfine = 0 | (2) | ||
Wet ash < 20 cm thicka | α ≤ 30° µfinewet = 1 | 30° < α < 35° µfinewet = (35 – α)/5 | 35° ≤ α µfinewet = 0 | (3) | ||
