Understanding the Specifications

Before we can design the layout and functionality of an access floor we must first determine the load capacity and tolerance. To do this we must ask:

1. What will the floor be used for? For example cable management or air plenum.

2. What is the environment and purpose of the building? For example general office area, gaming area, education facility etc.

3. What equipment will be placed or rolled onto the floor on a routine basis. For example racks, safes, cabinets etc.

4. Are there any foreseeable changes that might change the concept of the original floor? For example a small computer room being changed into a heavy duty compacts room.

Once these questions have been resolved, we may then select the loading grade of the panel. But in order to understand the different load tolerances, we must define what loads the access floor and pedestals will incur. 

Concentrated Load
A load is applied over a 25 x 25mm steel indentor onto the panel at its weakest point. Once the load has been removed, the deflection or permanent set of the indentor movement must not exceed 2.5mm.

Ultimate Load
A load is applied over a 25 x25mm steel indentor onto the panel until the system fails structurally. The ultimate load should be three times the concentrated load.

Uniform Load
Static force equally applied over the panel, and is typically imposed by stationary furniture.

Uniform load is tested by applying a load over a 1m² area. Once the load has been removed, the deflection or permanent set of the indentor movement must not exceed 2.5mm.

Impact Load
The effects or deformation of an access panel, when subjected to heavy loading being dropped onto it. A panels impact load is tested by dropping a weight from 900mm onto a 25 x 25mm steel indentor.

Supporting Heavy Loads

In situations where heavy loads need to be supported, it is important that all information relating to that equipment is considered before any decision is made, regarding the suitability of a specific raised floor system.
In some circumstances, it will be sufficient to use a panel with a higher load rating to accomodate for the extra load. However, there are alternatives.

Rolling Load
The durability of deformation of an access floor system when exposed to commercially anticipated caster traffic using a specified load. Rolling loads are defined by the number of passes, size and hardness of the wheel, and the combined weight of the cart and it's contents on each wheel.

When testing rolling loads, a load is rolled back and forth across the panel which is applied through 3 different size wheels.

The understructure of the access floor system is the major supporting element. As a result, careful attention needs to be paid to the type of understructure you specify for your project.

Loads that are to be considered in Understructure Support are:

Overturning Movement
Is a lateral load applied to the pedestal due to:

1. Rolling load traffic.

2. Underfloor work due to cable installation.

The pedestals ability to resist overturning movement is determined by:

1. Its attachment method to the structural slab.

2. Size and thickness of the base plate.

3. Pedestal tube size.

Axial Load
Is a vertical load applied to the centre of the pedestal due to concentrated, rolling, uniform and other loads applied to the surface of the access floor panel.

Seismic Load
Is a combination of vertical and lateral movement, usually in the form of earthquakes and plates shifting. When designing an access floor in a location with high seismic activity, it is critical to have a firm understanding of the seismic requirements of the access floor and understructure from the onset to avoid replanning or reinstallation of an appropriate system to cater for these needs.