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Medium Duty Modular Bracing System

A medium duty hydraulic bracing system for cofferdams up to 13.5m wide

  • For cofferdams, basements and tanks
  • Supports excavations up to 13.5m wide
  • One system fits many excavation sizes
  • Temporary works design available
  • Nationwide delivery

The Medium Duty Modular Bracing System is a hydraulic bracing frame for sheet piled excavations from 2.7m to 13.5m across. Wide clear spans give excellent access into the pit, leaving room to dig, lower in a tank or build a chamber below ground.

Typical applications

  • Attenuation tanks and storm water storage
  • Cofferdams for reinforced concrete structures
  • Basements
  • Pump stations and wetwells
  • Culverts and large diameter pipework
  • Deep manholes

How the system works

The frame sits inside the excavation as a ring of pre-cambered beams. Your crew can assemble it at the design level, then pump the double-acting rams out until the frame bears on the sheets all the way round. Pre-loading it this way is intended to keep the frame tight against the sheets and to limit ground movement outside the excavation.

The beams carry a slight inward curve, called pre-camber. That curve is designed to straighten under load rather than sag, so the frame can hold its line and span further between supports. Those wider spans are what give you the clear opening: room to dig, drop in a tank or build a structure without legs and struts in the way.

Modular and adaptable

The kit is a small set of standard parts: hydraulic rams, fixed extensions in 1.0m, 2.5m and 5.0m lengths, a telescopic mechanical unit, and walers. Combine them differently and you get the eight frame sizes, each covering its own band of the 2.7m to 13.5m range. The full span table is under Specification.

On wider excavations we can pair it with our Heavy Duty Modular Bracing System, which spans up to 21.5m.

Design and support

Frame levels, leg configurations and pre-load should all come from a design rather than be worked out on site. Our in-house engineers can produce temporary works designs to BS 5975, with drawings and calculations. Talk to us before you order and we can size the scheme around your excavation.

What is a hydraulic bracing system?
A steel frame with built-in hydraulic rams, designed to support the sides of a sheet piled excavation. The rams extend to press the frame against the sheet piles or trench sheets, holding back the ground so the excavation can keep its shape while your crews work inside it.
When do I need a bracing frame rather than a trench box?
A trench box suits a linear trench you work along; a braced cofferdam suits a hole you work inside. Once an excavation is too wide, too deep or the wrong shape for boxes, sheet piles with a hydraulic bracing frame can give you a clear, supported working area.
How much load can the medium duty system take?
The allowable loading is up to 150kN/m on beam lengths up to about 4.3m, and it reduces as the spans get longer. Our engineers can check the frame against the actual ground and water pressures at your site as part of the temporary works design.
Why are the beams curved?
The curve is pre-camber, built in deliberately. The beams are designed to straighten as the frame takes load rather than sag under it, which helps the frame hold its intended line and allows wider clear spans between supports.
How is the frame installed?
Components can be laid out at the excavation, lifted in by excavator or crane on chain slings, pinned together and then pumped up against the sheets. Your crew can then dig on below the frame to the design depth. Removal runs in reverse, releasing the pressure in a controlled sequence while the excavation is backfilled. The design documentation sets the actual sequence for your site.

Hire the Medium Duty Modular Bracing System

For help selecting leg configurations, a temporary works design or current hire rates, contact your nearest depot and we can put an engineer on it.

Questions? Talk to SEL about the Medium Duty Modular Bracing System

Our team is responsive, experienced and happy to help.

The rest of our bracing range, from manhole frames to the largest cofferdams