# Snow zones map – Italy

## What are the Italian snow zones according to Eurocode 1 ?

On the map of the national annex, the Italian territory is divided by provinces into three snow zones identified from 1 to 3. The snow zone 1 is subdivided into two to account for the Alpine or Mediterranean influence.

Zone | I-M | I-A | II | III |
---|---|---|---|---|

Characteristic value of snow on the ground without elevation
s_{k,0}
| 1.50 kN/m^{2} | 1.50 kN/m^{2} | 1.00 kN/m^{2} | 0.60 kN/m^{2} |

## How to determine the influence of elevation on the ground snow load in Italy ?

Distinct variation laws must be applied depending on each zone.

Snow loads are calculated as follows:

### Up to 200m:

\[\displaystyle s_{k} = s_{k,0}\]### Above 200m:

*Zone I-M*

*Zone I-A*

*Zone II*$}$

*Zone III*$}{\displaystyle$

where A is the elevation of the site.

## How to adjust the ground snow load according to return period in Italy ?

\[\displaystyle s_{n} = s_{k} \cdot \left[ \frac{ 1 – V \cdot \frac{\sqrt 6 }{\pi} \cdot [\ln(-\ln(1-P_{n})) + 0.57722] } {(1 + 2.5923 \cdot V)} \right]\]- P
_{n}is the annual probability of exceedence :

- dwl is the design working life, in years.
- V is the coefficient of variation of annual maximum snow load with V=0.2 for a recurrence interval less than 50 years and V=0.6 for a recurrence interval greater than 50 years.
- It should not be applied for annual probabilities of exceedence greater than 0,2 (i.e. return period less than approximately 5 years).

## Example of results given by the software Eurocodes Zoning

### B1 – Localization

- Coordinates in World Geodetic System 1984 (WGS84) 10.5188° , 43.7455°

Address 56011 Calci, Toscana

### B2 – Elevations

Coordinates | 10.5181°, 43.7303° | 10.5198°, 43.7596° | 10.5198°, 43.7596° | 10.5179°, 43.7901° |
---|---|---|---|---|

Elevations | 60m | 798m | 798m | 109m |

Obstacle effective height H | 738m | 689m | ||

Slope actual length
L_{u} / L_{d}
| 3261.4m | 3379.8m | ||

Slope angle Φ | 22.6% | 20.4% | ||

Horizontal distance site/top x | 1571.5m | |||

Elevation at the place of construction | 216m |

### B3 – Building

- Type of building: monumental building
- Design working life category: 50 years
- Max height: 10m
- Orientation from North: 15°

### B4 – Terrain categories

Sectors | 1 | 2 | 3 | 4 |
---|---|---|---|---|

Categories | C | C | B | B |

Sectors | 1 | 2 | 3 | 4 |
---|---|---|---|---|

Sector definition | from 330 ° to 60 ° | from 60 ° to 150 ° | from 150 ° to 240 ° | from 240 ° to 330 ° |

Distance to shore | > 100 km | > 100 km | 21.3 km | 19.5 km |

Exposure category | III | III | III | III |

### C1 – Snow

UNI EN 1991-1-3 Appendice nazionale 24/09/2010

- Zone : III(s
_{k,0}= 0.6 kN/m²) - Criteria for zoning : Pisa, Toscana
- Characteristic value of snow on the ground at the relevant site : s
_{k,216}= 0.613 kN/m² - Ground snow load with a return period of 50 years : s
_{50 ans}= 0.613 kN/m²

### C2 – Wind

UNI EN 1991-1-3 Appendice nazionale 24/09/2010

- Zone : 3(v
_{b,0}= 27.0 m/s) - Criteria for zoning : Pisa, Toscana

Sectors | 1 | 2 | 3 | 4 |
---|---|---|---|---|

Sector definition | from 330 ° to 60 ° | from 60 ° to 150 ° | from 150 ° to 240 ° | from 240 ° to 330 ° |

Value of the basic wind velocity from the map
v_{b,0}
| 27.0m/s | |||

Elevation above which wind velocity increases
v_{b,0}
| 500m | |||

Fundamental value of the basic wind velocity
v_{b,0}
| 27.0m/s | |||

Shape parameter K | 0.138 | |||

Exponent n | 1 | |||

Annual probability of exceedence p | 0.02 | |||

Probability factor
c_{prob}
| 1.0 | |||

Directional factor
c_{dir}
| 1.0 | 1.0 | 1.0 | 1.0 |

Basic wind velocity
v_{b}
| 27.0m/s | 27.0m/s | 27.0m/s | 27.0m/s |

Reference roughness length
z_{0,II}
| 0.05m | |||

Roughness length
z_{0}
| 0.1m | 0.1m | 0.1m | 0.1m |

Terrain factor
k_{r}
| 0.2 | 0.2 | 0.2 | 0.2 |

Height above ground z | 10.0m | |||

Minimum height
z_{min}
| 5.0m | 5.0m | 5.0m | 5.0m |

Roughness factor
c_{r(z)}
| 0.921 | 0.921 | 0.921 | 0.921 |

Obstacle type | isolated hills | |||

Exposure type | downwind | – | upwind | – |

Factor depending on the type and dimensions of the obstacle
s _{max}
| 0.444 | 0.0 | 0.282 | 0.0 |

Orography factor
^{*} c_{o(z)}
| 1.181 | 1.0 | 1.128 | 1.0 |

Mean wind velocity
v_{m(z)}
| 29.4m/s | 24.9m/s | 28.0m/s | 24.9m/s |

Turbulence factor
k_{l}
| 1.0 | 1.0 | 1.0 | 1.0 |

Standard deviation of the turbulence
σ_{v}
| 5.4m/s | 5.4m/s | 5.4m/s | 5.4m/s |

Turbulence intensity
I_{v(z)}
| 0.184 | 0.217 | 0.193 | 0.217 |

Air density ρ | 1.25kg/m^{3} | |||

Exposure factor
c_{e(z)}
| 2.706 | 2.138 | 2.532 | 2.138 |

Peak velocity pressure
q_{p(z)}
| 1233.0N/m^{2} | 974.0N/m^{2} | 1153.8N/m^{2} | 974.0N/m^{2} |

Peak wind velocity for Serviceability Limit States
v_{p(z),SLS}
| 159.9km/h | 142.1km/h | 154.7km/h | 142.1km/h |

Peak wind velocity for Ultimate Limit States
v_{p(z),ULS}
| 195.8km/h | 174.1km/h | 189.4km/h | 174.1km/h |