LED Wall Ballast Simulator

How it works. The wind pushes on the whole screen at half its height plus 0.1 m. The screen, the back frame and the ballast try to hold it down about the toe of the base. Following the sheet: wind force × arm × safety factor = screen + frame + ballast moments. With wind from the rear the toe is under the screen (screen arm 0, frame arm 0.46 m, ballast arm 0.862 m). With wind from the front the toe is at the rear of the base (screen arm 0.922 m, frame and ballast 0.46 m). Wind pressure is ½·1.25·v² (the sheet's table). The sheet's wind scale is the Beaufort scale, and picking a Beaufort force here uses the top of its speed range (force 6 is 13.8 m/s). Angled wind counts by cos θ. Outdoors, gusts raise the design wind to the peak speed, and the animation replays them. Indoors, wind is not the real load. Air in a hall hardly moves, so the sheet's wind scale really stands in for sideways loads nobody has measured: a draught, a bump, a wobbling floor. Here you can pick them one by one. A door gust is air at your speed for a few seconds. A knock is a push at one height shared by a few bases (the ergonomic limit for a whole-body push is about 23 kgf, and a braced person can reach about 70 kgf; CCOHS). Stage sway moves the deck back and forth by a few millimetres, so every mass feels the acceleration (2π·f)²·amplitude. An earthquake shakes the ground; the Greek seismic zones design for 0.16, 0.24 and 0.36 g (Greek National Annex to Eurocode 8), and a rigid object on an upper floor feels up to 2.5 times the ground (EN 1998-1, 4.3.5). The code minimum is the sideways load that temporary-works rules such as BS 5975 ask for when nothing else is known: 2.5% of the vertical load, a stand-in for out-of-plumb and rough handling. For shaking the force on each mass is its weight times the acceleration, so the ballast itself is shaken too, and the wall can tip either way: the screen side is the weak one, because the screen's weight sits at the front toe. With "Auto" the ballast goes where it helps most: at the rear end for a forward tip, in the middle when the load can come from both sides. The safety factor is the ratio of the tipping acceleration (or push, or gust) to yours, as in the sheet. It treats the load as steady, so it is cautious for short loads: the animation also lets the wall rock, and a brief gust or push that lifts the wall can leave it standing. A sudden load on a strapped wall can double the strap's pull, which the static number does not show. Straps and stage. A strap, cable or truss is a spring from the screen to an anchor. The wall is also a cantilever that bends, so the strap only pulls as hard as the wall moves it, plus the lift of the base. The program finds the largest wind the wall can take before a strap reaches its rated load or the wall passes its tipping point. On a stage it checks two ways of failing and shows the worse: the wall tipping on the deck, and the stage and wall tipping together about the stage edge. Assumptions. Straps are hand-tight with no slack: a loose strap lets the wall start to fall before it pulls and then takes a shock load, so keep them tight. Bending stiffness is illustrative (about two 50×50×3 aluminium posts 0.38 m apart per base), set it to your frame in Advanced. Ratchet straps stretch up to 7% at rated load (EN 12195-2), steel cable 0.4%, a truss 0.03%. Steeldeck stage decks are rated about 7.5 kN/m². Frame strength, cabinet locks, anchors and ground are not checked. Sliding is an extra check; the sheet assumes enough friction. Beaufort 1 in the sheet's table lists 0.14 N/m² for 1.5 m/s, which should be 1.4, so 1.4 is used here. Cabinet weights come from Unilumin datasheets (Uslim4 13 kg, Uslim2 7.8 kg, USlim-O3 14.8 kg, USlim-O4 32 to 34 kg) and a distributor listing (UGC 5.6 kg). This is a rough reference. As the sheet itself says, it cannot replace a structural simulation or a practical test. Use it to see how a wall reacts and to size a first guess, and have a qualified rigger or engineer approve any real installation.