Steel and Timber Tower at RRH Benbecula

Location:Isle of Benbecula, Outer Hebrides

Sector:Defence

Service:Fabrication and Installation of Structures

LARS Communications has recently completed the design, fabrication and installation of a 40m steel and timber tower on the Isle of Benbecula in the Outer Hebrides.

OBJECTIVE

LARS Communications was the principal contractor on the project, responsible for the design, build and installation of the new 40m tower, including the sourcing of the timber specialists, Berkshire-based McCurdy & Co.

Tower Design, Build and Installation

The new steel and timber tower was designed by LARS’ design partners, MFDCI Limited, and built-in sections in the in-house fabrication workshop at LARS’ Carnforth base. The timber section, required to reduce radar reflection at the RAF site, was built at McCurdy & Co’s Berkshire base.

Installation of the Structure

Section 1:

  • The assembly of the structure will be in accordance with the GA drawings and with the use of crane.
  • The first section will be face built on the floor then lifted onto 2 of the stub legs utilising spreader beam. The legs will be bolted to splice plates and tightened.
  • A temporary brace will then be attached on 2 sides adjacent to face. (See Drawing)
  • The face can then be climbed and the crane slings/chains can be removed
  • The opposite face of the tower will then be lifted up with the 2# top horizontal braces attached and temporarily secured to prevent it swinging around.
  • The face will then be lifted onto the stub legs utilising the spreader beam and bolted to splice plates and tightened.
  • The Top 2 Horizontals will then be lifted up pivoting on the bolt and attached to the opposite leg.
  • The temporary brace can now be removed
  • All infill tower members can now be installed.
  • Ladder can now be installed and anchored to the concrete base

Section 2:

  • The tower will be assembled on its side in accordance with the GA drawings
  • Across the K-bracings on 4 sides a temporary brace will be installed.
  • Temporary feet extensions will be added to the bottom of the 4 legs
  • The section will then be lifted and turned vertical with the use of the crane
  • All temporary braces and feet can now be removed.
  • The tower will then be lifted and landed on top of section 1
  • A team of climbers will ascend the tower to connect and bolt the 2 sections together
  • Section 1 can now have the bolts tightened

Sections 3 and 4 were carried out repeating the sequence used in section 2.

Timber Section 1:

  • The Timber section will arrive already assembled
  • Lift section on top of the steel tower 22m and connect the 2 together as per GA drawing
  • Connect ladder interface
  • Connect earth tape to steel tower lug

A full bolt check was undertaken by a team of riggers working in an orderly manner around the structure.

On completion of the works, a safe to climb certificate was issued. All packing material and installation waste was bagged and boxed up and removed from the site. No material was left on site other than those forming part of the installation. All waste was disposed of responsibly, in accordance with environmental guidelines.

Scope of works:

  • Provision of detailed design
  • Fabrication of 22m steel lattice tower (in sections)
  • Fabrication of 18m timber section
  • Pre-deployment activities
  • Provision and installation of a new tower structure
  • Construction of steelwork frame segments
  • Stair installation
  • Installation of GRP handrails, GRP decking and flooring panels
  • Davit installation
  • Installation of demountable platform frame
  • Installation of demountable decking and hand rail
  • Full bolt check
  • Installation of timber section – lift timber section on top of the steel tower and connect the two together
  • Connect ladder interface
  • Connect earth tape to steel tower lug
  • Safe to climb certificate issued
  • On completion of all works, the site was cleared of all materials and waste and the site left in a clean and tidy condition
  • All redundant materials are disposed of in an environmentally responsible manner

Outcome

This was another upgrade as part of Project HYDRA and presented a unique challenge – our first part steel, part timber tower. Working closely with our design partners, MFDCI Limited and McCurdy & Co., the specialists responsible for the reconstruction of Shakespeare’s Globe Theatre in London, we worked diligently and collaboratively, delivering the project smoothly, on time and on budget.

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