Think of heavy lifting and the first picture in your mind may be of a big Demag or Manitowoc crawler crane lifting a massive vessel at a refinery. But the pictures on these pages give just a taste of the various solutions for placing a heavy load: mobile crane, barge crane, hydraulic gantry and jacking systems.
Mobile cranes
Ainscough Crane Hire of the UK was brought in by building contractor Arren Building Concepts (ABC) to carry out a big lift at Ipswich Town Football Club’s Portman Road stadium. The main roof truss for the new North Stand was 92m long and weighed 117t. The cranes required to dual lift the huge truss into place were Ainscough’s 800t Demag AC 2000 (production name: AC 650) and 500t Demag AC 1600. Ainscough also supplied a man basket, an extensive selection of lifting equipment and a team of experienced personnel.
The cranes were set up on a road outside the stadium. The AC 2000 was rigged with 120t of counterweight, with 50.5m of main boom and superlift. The AC 1600 was rigged with 140t of counterweight and 45.1m of boom.
Once both machines were rigged and all final checks had been carried out the cranes raised the truss in unison at a 20m radius to its final height and held it in position while it was connected by ABC operatives.
Barge cranes
Dutch company Smit was towing sailing ships from the sea to the harbour of Rotterdam as long ago as 1842. Since then it has developed a range of maritime services including heavy lift, for which it has a range of floating cranes.
The company’s sheerlegs Taklift 5, which has a lifting capacity of 400t, sailed up the River Thames late last year to visit central London to erect steelwork for the new footbridge adjacent to the Hungerford rail bridge at Charing Cross. Working for the main contractor Costain Norwest Holst joint venture, the sheerlegs erected steel pylons in a continuous six night cycle. As the work required possession of the railway bridge, work was restricted to nights.
The pylons, each weighing about 45t, support the concrete footbridge and were fabricated by Butterley Engineering down river and transported to site by barge. Then, Taklift 5 lifted each pylon off the transport barge, rotated it to the vertical using its two main lifting blocks and moved across the river under its own propulsion to the bridge to install it in position. A high height hook was needed to reach over the deck launching gantry and a long outreach was needed to place the A-frame pylon onto the Embankment. For these reasons the crane was fitted with its 33m fly jib.
‘Using a sheerlegs meant that all steel work could be installed from the river which reduced onland congestion and also meant no expensive or complicated temporary works were necessary,’ explains Smit sales manager Rutger Kouwenhoven.
Having completed the up river pylons, Smit will soon be returning in 2002 to install the pylons for the other footbridge.
(This footbridge over the Thames should not be confused with the Millennium footbridge 2km downstream which opened in July 2000 and was immediately closed for more than 18 months for remedial works because it was prone to swaying if too many people walked across it at the same time. The Wobbly Bridge, as it is more commonly known, was designed by Sir Norman Foster and Ove Arup & Partners, and cost £18m ($27m) to build and £5m ($7.5m) to put right.)
Hydraulic gantries
Sometimes cranes are not enough. To move a heavy load takes heavy duty trailers and, if there is no access for a mobile crane or no headroom for a boom, a hydraulic gantry may be used for the lifting. Sometimes it is just easier to use a gantry system. Such a project was carried out last year by Transpesa Della Volpe of Brazil for Enron’s thermal power plant in Cuiabá, Argentina.
Transpesa was responsible for getting the main components of a turbine and generator from Buenos Aires to Cuiabá, where they would be assembled. Most of the journey was by river barge but on reaching the landing stage near Cuiabá it was necessary to build up an intermediate ramp between the barge ramp and the jetty to allow the turbine and generator to be rolled off. To remove the loads from the barge Transpesa used a transport set composed of a prime mover and 16 axles with a capacity of 30t per line (480t total).
After removal from the barge, the first transport set travelled approximately 2km to the transshipment area, where the second transport set with 16 axle lines, girder bridge, another 16 axle lines, and two prime movers were located. These were to be used to transport the components along a highway to the jobsite at Cuiabá.
In the transshipment area the turbine and generator were off-loaded by use of a Lift Systems 34PT500LT hydraulic telescopic Power Tower gantry with capacity of 500 US tons. The turbine and generator were set on wood cribbing during assembly of the transportation set around them.
In Cuiabá this transport set was disassembled and the turbine and generator were transshipped to another transporter set (the same one which was used to remove the components from the barge) to enable manoeuvring inside the jobsite and bring the components closer to their foundations. The Lift Systems Power Tower was used again to make this transfer.
The Power Tower was used once again at the final destination to unload the components from the transport set, take them inside the building and set them on their foundations.
Jacking systems
When the airline Virgin Atlantic wanted a new hanger at London’s Heathrow Airport last year, the construction timetable was restricted. To meet the programme it was decided to construct the roof on the ground and then lift the entire structure, as a single section weighing 560t, up to the top of the building.
PSC, now called Fagioli PSC, had done this kind of thing before, notably in a similar development for British Airways, and so was called upon to provide a lifting solution.
The main contractor for the £32m ($48m) hanger project was Interserve Engineering Services, while PSC Fagioli was working to the structural steelwork specialist Rowen Structures Ltd.
The roof was initially lifted 6m in September 2001 using PSC’s hydraulic strand jacking equipment and was held in position for several weeks while additional permanent steelwork was added. The main lift was then carried out using a computer control system that was completed during a one day operation in December.
Eight L600 jacks were used for the lift, connected in pairs to each column with L50 tie back jacks attached to the cantilever beam of each column. L15 jacks were available for use as storm guys.
The use of the jacking system reduced the critical construction period by eight weeks and had the added benefit of not interfering with the airport’s radar. This meant that work was allowed to continue in normal working hours rather than restricted to the night time 23.00 to 06.00 period when there are no takeoffs or landings at Heathrow.
