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Weston-Super-Mare's pier rises from the ashes

A fire in the summer of 2008 destroyed the historic pavilion on Weston-super-Mare’s pier. Rising from the ashes, with a build programme of just 49 weeks, a bigger pavilion is getting ready to open in the summer. Jessica Rowson reports.

The pier at Weston-super-Mare, which extends 400m into the Bristol Channel, is a much loved icon at the small seaside town. But a fire in July 2008 totally destroyed its Grade-II listed, 105-year-old pavilion.

Little was left of the mostly timber construction at the end of the pier apart from its piles, which jutted upwards from the sea, and the connecting gridwork of primary deck beams.

The fire was devastating news for the pier’s new owner.

“We bought the pier in February [2008] and started a refurbishment programme,” says pier owner Kerry Michael. “We invested £2M between February and July. In July we had the fire and lost the pavilion. The fire lasted little over an hour but destroyed the entire building and contents to the point that it couldn’t be recognised.

John Sisk worked on site in all weather conditions

The new pier has a rebuild programme of only 49 weeks

“It had contained 400 slot machines but there was no trace of them after the blaze. We carried away wheelbarrows of coins all melted together.”

Since then, no time has been lost bringing forward proposals for a new pavilion, at a cost of £26M. The floor space of the new building will almost double the size of the pavilion from 0.5ha to 0.9ha spread over three floors. It will include bigger and better rides plus a 90m high panoramic tower.

Before work could start on rebuilding the pavilion, the deck of the pier had to be reconstructed to provide a working platform.

The pier’s primary beams managed to withstand the fire without too much damage but the smaller secondary beams spanning between the primaries needed to be replaced.

This proved a challenge as the piles for the pier has settled differentially over the years, distorting the shape of the original primary beams

“The primaries are all funny shapes,” says contractor John Sisk’s senior contract manager Richard Sutton. “They go up and down as the piles have settled.”

The floor space of the building will nearly double in size

The floor space of the building will nearly double in size

To overcome the irregularity of the structure, Sisk did a thorough survey and then proposed a detail which would allow for flexibility when fixing.

“We fixed a cleat [a steel plate welded onto the web of the beams] with holes predrilled along the primary beam to give a constant detail,” says Sutton. “We then lowered the [secondary undrilled] beams, clamped them in place and drilled the holes insitu for the connection.”

Sandwich plate system (SPS) panels - light, thin structural floor panels made from two metal plates bonded with a polyurethane elastomer core − are being used for the pier deck flooring. These sit on the grid of steel beams.

The system exerts a load of just 1kN/m² so there is no danger of it overloading the existing 105 year old pier structure. Yet it is robust enough to carry heavy loads, including small mobile cranes.

“It’s a direct replacement for heavy engineering technology,” says SPS developer Intelligent Engineering regional director Giles Pendleton. “It’s about a quarter of the thickness and a third of the weight of a concrete alternative.”

The panels were first used in the marine industry and have only been used in civil engineering applications in the last few years, after extensive acoustic and fire testing.

Panels sit on a grid of steel beams

Panels sit on a grid of steel beams

The installed SPS panels provide an immediate load platform for mechanical equipment, materials and people. As a section of floor is completed, work can begin on the main structure.

“It’s a simple structure, with no propping and no curing,” says Pendleton. “It’s instantly available.” Landing the SPS panels opened up the project and provides a working platform. A Unic spider crane is now working off the panels to erect the steelwork of the main pavilion.

The panels are 10m by 2m and are connected to each other on all four sides by bolted on shear plates, forming a continuous deck. “No specialist installation is needed − it’s a bolted solution like Meccano,” says Pendleton.

The first SPS panels were delivered at the end of last September and the last for the pavilion was placed before Christmas. In total approximately 200 panels − or 4,000m² − of SPS will be used to create the floor plate.

At the same time as the deck is being completed, work is progressing on the pavilion superstructure, with the first piece of steel erected last October.

The Grand totals of the Weston-Super-Mare pier

  • £26M: Cost of bigger and better pavilion
  • 400m²: Of SPS will be used to create the floor plate
  • 105 years: Age of existing pier structure

 

The new pavilion will be considerably bigger than the old one and so new piles have been installed between the existing piles to support it. The existing piles will carry the load of the ground floor deck only and the new piles will go through the ground floor deck and carry the load of the new pavilion above.

“What we wanted to put back was much heavier, so the piles survived, but they were useless for the new building,” says Michael.

“We installed 68 new piles for the new building and the deck sits on the original piles. The new piles come through the deck and the new building sits on them.”

Piling contractor Commercial Marine Piling drove these new tubular steel piles − typically with a 457mm diameter − into the sea bed using a 180t crawler crane on a 1,500t spud leg barge. It finished this part of the job last July.

The piles are cantilevering out of the seabed by 10m and the piling tolerance is typically +/-75mm. The construction team had two challenges − to bring the line of the piles back to where they should be and to stop the piles moving.

Artists impression of the new Grand Pier

An artists impression of the new Grand Pier

John Sisk surveyed the position of the new piles and fabricated bespoke pile head extensions which could be clamped onto the top of the pile and used to bring the base plate for the superstructure column back into line where needed. Similar to the primary beam cleat detail, the base plate on the top of the pile head extension where the superstructure column will sit is not predrilled − the column is carefully guided into place and drilled on site to ensure fit.

“The fabrication of the pile head extensions accounts for the pile being out of position,” says Sutton. “They were all bespoke. Also having no holes in the base plate [and drilling holes when the column is in place] helps to get over the lack of waggle.”

The pile head extension is the same diameter tube as the metal pile to which it is attached and is fixed onto the pile with a collar that clamps the two together. This collar, which is level with the deck, also clamps onto the deck, providing a restraint at the top for the previously cantilevering pile, preventing further movement.

This is the only point at which the new pavilion is connected to the existing structure, as otherwise they are two independent structures. The collar is fixed with a 8mm rubber gromit, so that while it prevents the pile from moving. It also allows for differential settlement of the new piles relative to the old pile.

 

Access challenge

Snow covers the Weston-Super-Mare pier

Snow covers the Weston-Super-Mare pier

John Sisk started on site shortly after being awarded the contract and worked off cranes on weather susceptible barges in a bid to get going as soon as possible.

“Craneage was a difficult aspect,” says Sisk senior site manager Michael Tipton. “We used cranes off barges due to the quick lead in time of the project but in bad weather we couldn’t use them.”

Key equipment included two spud leg crane barges − one 500t with an 80t crawler crane and the other 1,500t with a 180t crawler crane on board − supplemented by a jack up barge loaded with an 80t mobile crane from the beach.

During bad weather, the barges had to shelter − initially at Cardiff Dock on the other side of the Bristol Channel, and then in a deep water anchor site. Now that a jack up barge is on site, weather has been less of a concern.

Getting an 80t crane onto the jack up barge 240m out to sea was a challenge. The pier was too weak to hold the crane so instead John Sisk used sand to create a ramp, 20m long and 3m high to allow the crane to drive from the shore to the barge. “The ramp was the quickest method to put the crane on the barge,” says senior contract manager Richard Sutton.

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