Derby WTW Bio-Energy Plant

Project Brief

We were asked to design a multi-service support bridge that could carry both water, gas, & air pipework and cable containment, spanning 15 metres from the bio plant into a digester tank, 10 metres off the ground for a bio-energy plant in Derby.

Solution

In the majority of cases a bridge of this size would be fabricated on-site using traditional steel but we designed this bridge from modular secondary steelwork saving the contractor time and money.

The primary challenge was designing a bridge that could support the dead load of the services, totaling nearly 2500kg, and any forces from the flow of water through the pipework. Due to the location of the pipe bridge we took into consideration dynamic forces such as wind and snow loading and combined load calculations to ensure the structure is fit for purpose. To reduce the risk of undue stress on the structure we braced to three supporting pairs of legs, which were themselves both tied and braced in the other direction. Suspended from the bridge were 14 trapeze brackets to support 900kg of cable containment, which were all hot dip galvanised protecting against corrosion.

Last but most certainly not least, we specified resin studded chemical anchors which were fixed into the concrete.

The bridge was part assembled in our workshop and due to the secondary modular steelwork used it was able to be assembled relatively quickly once arriving on-site, saving the contractor time and money. The final product used a mix of both Framo 160 and Framo 80 sections, chosen because of their high strength, and adjustability, and flexibility when compared to traditional steelwork.

The pipe bridge was pre-fabricated in-house and delivered to the site for installation.