One of the most important but often overlooked components of a trench drain system is the load bearing frame. This is the typically a metal component at the top of the trench drain that takes all the abuse from the traffic. When this frame is properly selected it will take the loading applied to it and properly distribute the load to the surrounding concrete. This frame also must be evaluated for environmental concerns and aesthetics to ensure it works with all aspects of the design.
Load Bearing Frame Selection
Standards
There are several published documents about proper design of the load bearing frame. It is relevant to understand these standards before continuing with this discussion. These standards are typically developed to ensure the design community gets a minimum level of quality that protects the design intent without having to be an absolute expert in each and every field. Dura Trench believes the EN1433 (formerly known as DIN) standard for trench drains is probably the most defined and well written. This standard is our principle of design and notes the following:
- Edge and contact surface protection is mandatory for trench drains of classes D to F and recommended for class C.
- For load classes D through F, the edge and contact surface shall be secured against disconnection of the channel units by traffic (e.g. by anchors.)
- Trafficked edges and contact surfaces between channel bodies and gratings or covers shall be either cast iron, galvanized steel, or stainless steel.
- The trafficked edges shall meet a specified thickness.
- Class C frames shall be 0.078″ thick at trafficked edges and 0.039″ thick at grate seat.
- Class D frames shall be 0.157″ thick at trafficked edges and 0.078″ thick at grate seat.
- Class E and F according to design but not less than class D.
- The grate and edge height shall be +/- 1mm in height.
Frame Design
Dura Trench believes that the frame is the heart of the trench drain system. This component takes the load from the traffic. The frame is also cast in the concrete so you only get one chance to get it right. We see heavy load class grating specified without any frame all to often.
Dura Trench frames are designed to allow contact between the concrete and the frame. This contact is called the bearing area. This bearing area is what separates our products from many on the market. Many trench drain systems commercially available transfer the traffic loads into their channels. They do this by having frames that sit directly on top of their channel walls with no interaction with the surrounding concrete. When you purchase this type of system the channel material becomes extremely important because it is now a part of the structural integrity of the design. In many cases these compressible plastic materials are directly under the frame allowing flexing and eventual failure of the channel wall or the surrounding concrete. Dura Trench frames overhang the trench body and transfer the loads to the surrounding concrete. Our frames do not put those loads into the channel body.
Another common industry problem is a lack of concrete anchors or poorly designed anchors. There are many products on the market today that don’t have any anchors at all, some companies have them but have reduced their diameter to save cost thereby reducing their efficiency, or made them so short or at improper angles for shipping purposes that they are ineffective. Dura Trench does not skimp on this extremely critical component.