# Wind Flow on Laterally Open Structures According to DIN 1055-4

## Technical Article on the Topic Structural Analysis Using Dlubal Software

### Technical Article

Since wind on laterally open structures is not addressed in the Eurocode, the 4 cases of the German DIN 1055, Part 4 are referenced.

#### Building with only One Open Side

In the first case, wind flows in RWIND Simulation are applied to a building that has only one open side. There, the wind blows into the building.

Positive cp values indicating pressure inside the building are displayed in red. Suction areas on the outside are displayed in blue.

The next animation shows wind flows at a 90° angle.

Here, only negative pressure, or suction, occurs inside the building.

Then, the wind blows from behind the building; that is, at an angle of 180°.

Again, suction occurs inside on all surfaces.

#### Building with Two Adjacent Open Sides

In the second case, the wind flow is applied to a building with two adjacent open sides.

With a 0° wind direction, pressure occurs on the inner surfaces.

Now, the structure is analyzed at a 90° flow angle.

Only the exterior surface where the wind blows undergoes pressure. All other internal and external surfaces are subjected to suction forces.

#### Building with Two Opposite Open Sides

Now, we look at what happens when two opposite sides can be considered as open; that is, at least 30% of the sides considered to be open are fully open.

All inner surfaces undergo suction at a 90° angle.

The situation is different when a wind load is applied in a non-orthogonal direction. Also, this load case could potentially govern for the structural design and should be considered.

By evaluating the cp values in RWIND, it becomes clear that inside pressure and suction areas are opposite, and thus the resulting loads have the same direction.

#### Building with Three Open Sides

Finally, a building that is open on three sides is calculated in RWIND Simulation. Only one wall is considered to be closed.

As expected, a positive pressure is generated on the surfaces inside the building at a 0° flow angle, visible by the red color.

According to this regulation, the governing load case for maximum suction forces inside is the non-orthogonal wind blowing at a 135° angle.

In this model, only negative pressure forces are generated on the structure's internal side.

The last case to be examined is a structure open on three sides with a 180° flow angle.

In this scenario, negative internal pressure (that is, suction) is generated as well.

#### Dipl.-Ing. (FH) Andy Kohl

Marketing & Public Relations

Mr. Kohl is responsible for public relations, especially video marketing.