Wind action evaluation on vaulted roofs


The present article explains how to determine wind loads on vaulted roofs at the Eurocode 1. Specifically, we will show how to use Figure 7.11 from EN1991-1-4, which provides the external pressure coefficients on vaulted roofs with rectangular base:

We will consider a structure with following dimensions:

f = 2,51m

h = 3,20m

d = 9,60m

The developed length of the vaulted roof will be split into 4 equal parts, for zone A, zone B (repeated twice) and zone C:

For each of these zones, the external pressure coefficient (Cpe10) is read on a graph, depending on the f/d and h/d ratios.

In our case:

f/d = 2,51 / 9,60 = 0,26

h/d = 3,20 / 9,60 = 0,33

  • For zone A

We start on the f/d axis until we reach the two diagrams related to zone A:

  • For h/d = 0, we read Cpe10,A = +0,42
  • For h/d ≥ 0,5, we read Cpe10,A = +0,16

We then perform a linear interpolation because in our case, 0 ≤ h/d ≤ 0,5:

For h/d = 0,33, we get: Cpe10,A = +0,25

  • For zone B

We start on the same position on f/d axis, but this time, we reach the zone B diagram.

We read: Cpe10,B = -0,96

  • For zone C

We read: Cpe10,C = -0,40

In the end:

For zone A => Cpe10,A = +0,25

For zone B => Cpe10,B = -0,96

For zone C => Cpe10,C = -0,40

Starting from version 2021, vaulted roofs at the Eurocode 1 are covered by the climatic generator of Advance Design.

Wind actions, whether 2D or 3D, are instantly generated:

As prescribed in the Eurocde 1, roof is divided into 4 equal zones.

The name of each zone as well as their Cpe value can even be displayed with a dedicated annotation:

Conclusion

The evaluation of wind action on vaulted roofs by reading the graph from the Eurocode 1 can be tedious, with a high risk of error.

Fortunately, in Advance Design, this process is fully automated. Wind forces are created instantly, and they can be updated in a single click whenever a modification is made on the building.

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