Accidents caused by storms occur time and again. Recently, in the summer of 2019 parts of an LED wall happened to fall into the crowd during a concert. This was caused by severe gusts of wind. The reason for these accidents usually coheres with a wrong and poor installation.
When LED walls come into use outdoors, several factors need to be considered: how and where is the wall positioned? Could the wind blow around the screen and cause a pull? Is the construction prepared for changing wind directions? And in case of emergency, how fast could the wall be dismantled?
Especially strong fusts can influence the performance and the structural integrity of a screen. What exactly happens with an LED wall that gets hit by a gust of wind depends on many, often rather complicated factors: how heavy and big is the wall and how is it wired? From which direction, and how strong is the wind blowing? How deep are the single panels? Could other nearby structures have an influence?
Wind force and standards
An LED wall is exposed to a higher load the higher it hangs. The standards for temporary constructions by DIN EN 13814 divide into four sectors: 0 to 8 meters, 8 to 20 meters, 20 to 35 meters, and 35 to 50 meters of height. The form of the construction hereby has direct influence onto the aerodynamic resistance, thus how much wind hits the structure.
Furthermore, it is to consider that the wind load can depend on the geographic location. Germany is divided into four wind zones: rather mountainous regions in the south are usually wind zones 1 or 2, the coast area belongs to wind zones 3 or 4.
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! The velocity pressure is determined with the fundamental value of the reference speed in 10 meters of height with an air density of ρ=1,25 kg/m³
! The conversion of the dynamic pressure in kg/m2 happens under the consideration of the acceleration due to gravity of 9,81 m/s2.
The stated value hereby refers to rigid structures. With so called non-rigid structures, e.g. a hanging LED wall, a dynamic interaction in form of swinging can occur between the wind and the construction. To what extent does that play a role for the safety of the wall?
Is an LED wall even allowed to swing?
If an LED wall starts swinging, the dynamic pressure onto the screen, the supporting system, and the single cabinet connections increases. A hanging LED wall is allowed to swing as long as the load increase for the LED cabinets as well as for the supporting structure is considered, and none of the components are damaged by the swinging.
Special caution is required with guyed constructions. Here, big internal forces can develop and they can quickly lead to an overload of the supporting structure and the LED cabinets. Constructions that are put into operation without a wind technical limitation in general need to be supported horizontally by the according parts.
Stable and safe despite a fast installation – does that work?
Weather can be unpredictable. If there is not even a gentle breeze blowing during the installation, the conditions might change quickly still. What demands should therefore be made on an LED wall for outdoor use?
Firstly, stability must be ensured. When more LED cabinets are connected to a big screen, they influence transverse forces and bending moment. The LED wall and all the other components need to be able to withstand these forces.
! Allowed bending moment with LED walls: 1 kNm to 6kNm
Otherwise the installation should be to complete as fast as possible. Time is money, and not only in exceptional circumstances are event technicians happy about a quick and easy construction and dismantling.
Less effort, more stability – our new Tri-Frame system
We developed our new Tri-Frame system based on these two prerequisites that comes as standard with the P4+WH Pro Outdoor series.
Most of the common LED screens are with their slim design not robust enough to defy wind effects. Therefore, it is usually necessary for outdoor projects to have an additional structural support like a beam or a traverse.
Our Tri-Frame catches wind load due to its depth and guarantees a safe and especially a quick construction and dismantling. Hereby the single cabinets are no longer secured with butterflies and stabilised with pipes, but by bolt connections with a truss system on the back of the individual cabinets. The traverses on the frames increase stability and enable extensive constructions without the necessity to intercept the structure horizontally several times. The depth to the back wall created by the Tri-Frame hereby leads to a significantly higher stability of the overall construction.