Performance criteria such as design loads and safety factors are often over-looked when evaluating an access flooring system. The PSA specification and now referred to as MOB PF2 PS/SPU outline a method of test for structural performance. This ensures compliance and provides guidance as to working areas where each floor grade may be used. Testing on under-structure evaluates the performance of the system as it will be used once installed. This is important because some materials used to make access floors show little or no visible damage before failing. A panel which fails without warning can be very dangerous in the event that it is overloaded.
Different materials fail in different ways. The chart below compares steel with concrete, two common materials used in access floor panels. As you can see steel will bend significantly before failing, providing additional warning and safety.
Yield Point – The yield point is the load at which permanent damage to the system begins to occur
Ultimate Load – The maximum load that can be applied to the system without failure or failing through the floor.
Design Load 1 – The safe working load that can be applied to the system determined by choosing the smaller value of the ultimate load divided by a safety factor of two or the yield point.
Design Load 2 – The multiple of the design load to the ultimate load.