Structural Steelwork in Action 5
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Structural Special Report Steelwork 02|04|15 >> in Action New Civil Engineer in association with BCSA and Tata Steel Showcasing innovative uses of steel, from transport to retail structures, plus the latest cost analysis. Contents | p02 Leeds Station | p04 Belfast Waterfront | p06 Costs| p08 Bradford Westfield | p10 The Curve, Slough Structural Steelwork in Action | Special report 04 | 2015 Complex: Cutaway of the new structure Making an entrance Leeds station entrance By Martin Cooper An eye-catching portal- leading around the station. It has been PROJECT TEAM as not to impede the flow of the river framed entrance estimated that up to 20% of the city’s during heavy rain. This has resulted in Main clients: Network Rail, West rail passengers will benefit from and the requirement for a steel transfer structure, built over Yorkshire Combined Authority will use the new entrance. structure at river deck level to support the River Aire, will help Architect: AHR Space for a new entrance south of the primary superstructure columns of Principal contractor: Carillion Rail alleviate passenger the station was extremely limited and the new entrance, as they do not align Structural engineer: Mott congestion at Leeds as the design had to incorporate access with the piers. MacDonald to the existing high-level concourse, a The transfer deck was the initial station. Steelwork contractor: William Hare location that straddles the River Aire phase of William Hare’s steel erection Steel tonnage: 370t was the only option. programme. The steel was installed via Big changes are afoot in Leeds as the It may be the right choice of location the on-site tower crane, which lifted the city takes on a new and dynamic but the new entrance’s site has members off barges and positioned post-industrial look. Although presented the project team with a host apartment blocks on two sides mean them between the new piers. manufacturing is still an important of challenges. the site is very constrained. The transfer deck is a series of source of employment in the greater “We’re building over water and so “The site also requires a large galvanized beams, positioned at 1.8m Leeds area, it is a different story in the we have river safety issues, and 63m-high tower crane which has been centres. The beams span 10.2m city centre, as banking, finance and subject to numerous wind stoppages,” between the new concrete piers and media companies dominate the explains Network Rail Project Manager cantilever a further 3.5m beyond the numerous new office developments. Luan Anderson. centre line of each pier providing Many of these new office schemes “The main reasons why a “We are also working next to and at support to the columns above as well have been built in an area to the south times over live rail lines, so some of our as support to an access and mainte- of Leeds station and in turn they have steel deck was specified work can only be done during nance deck around the perimeter of the created a demand for the new were the benefits brought by night-time possessions.” building base. pedestrian station entrance currently offsite fabrication and speed Before erecting the steel-framed The beams bear directly onto each under construction. of erection to reduce the entrance superstructure principal pier via a simple baseplate connection. The existing main entrance is contractor Carillion Rail had to install A series of beams cantilever 2.3m situated on the north side of the construction time above the piled foundations and two concrete beyond the southernmost primary station, and so commuters walking river” piers in the river (see box). beam to complete the curved plan from the south regularly cause John Svikis, Mott MacDonald The piers are positioned and aligned profile of the deck. pedestrian congestion on the pathways with the existing rail viaduct arches so “The main reasons why a steel deck 02 NCE in association with Tata Steel & the British Constructional Steelwork Association Structural Steelwork in Action | Special report 04 | 2015 RIVER WORK The location of the site means much of the work revolves around the River Aire. Carillion Rail has its main compound and an assembly yard about 1km downstream at Water Lane. Much of the project’s materials arrive at this yard and are then deliv- ered to the project by barge as this is the easiest way to access the site without negotiating the surround- ing narrow streets. “One of our initial tasks was to assemble a jack up barge and float it to the site,” explains Carillion project manager David Carlyle. “At 18m wide the barge provided a working platform for our 26t piling rig and an area from which we constructed the two concrete piers.” Steelwork contractor William Hare is also delivering all of its steel to the site via Water Lane, using a number of pontoons that can be Span: The structure is built above the River Aire. configured to suit the length and (Inset) The portal frame takes shape weight of the steel members. was specified were the benefits FOOTBRIDGES“xxxxxx” weekend rail possessions. The eastern brought by offsite fabrication and speed There are two external footbridges stiffened deck plates and secondary truss spans 17.7m and is 1.9m deep, of erection to reduce the construction that provide access for passengers sections. while the western truss spans 19.5m time above the river, which was from the east and west riverbanks The eastern bridge will be brought and is 2.3m deep. considered to be a positive health and into the new entrance as well as two to site as one fully completed element To help support the concourse safety decision,” says Mott MacDonald further bridges/ramps leading into and craned into position, while the extension, a new column has been project manager Jon Svikis. the viaduct arches. western bridge will arrive in two introduced on platform 15 on top of the Holorib metal decking, fabricated pieces. This is due to the crane lifting existing Victorian masonry viaduct. and cut to size offsite, spans between The eastern footbridge spans 9.5m, capacity restrictions. The shorter This has meant one of the viaduct’s the beams and provides formwork from while the western bridge spans section will be temporarily propped, arches had to be strengthened with which to safely fix reinforcement and 12.8m. Both are welded structures before the larger one is lifted into four plate girder ribs arranged in a cruci- pour a 160mm deep concrete floor comprising two primary box sections position. The two will then be spliced form. The steelwork is packed tightly to slab. Pockets were left in the slab ready supporting an arrangement of together insitu above the river. the existing masonry arch using high to receive the superstructure columns strength cementicious grout. and vertical bracing. The steel sections are 365mm deep Extending from the transfer deck is a frame, thereby minimising the overall of the individual frames, as well as via and 325mm wide, fabricated from new suspended floor and escalator pit cladding build-up and maximising the the 20m-high braced lift shafts that are 45mm plate for the flanges and 25mm that extends through the existing internal space available,” says Svikis. positioned to the north adjacent to the plate for the webs. Each of the four ribs masonry arch. The floor structure The portals are a maximum of 20m existing masonry viaduct. There are 11 is bolted into the existing masonry pier comprises two upstand trusses that tall, with a horizontal span of frames at river deck level; and nine at the springing point, via 1m deep span 15m and are 2.1m deep. approximately 12.5m. Each frame more extending above three existing haunches and 40mm thick end plates. Sitting on the transfer deck, the comprises two vertical legs and a railway lines to form the connection As well as the access points from the entrance superstructure is a series of curved arch section of varying radii of with the high level concourse. high level concourse, low level access to portalised arches at 1.8m centres. between 2.8m and 12.3m. This involves construction of a new the new entrance will be provided by “The close spacing is to allow the Generally the frames are being “Ticket Barrier level” above platforms two footbridges (see box) spanning structural zone to be minimised, reduce erected in four pieces. The frames are 15,16 and 17, crossing three electrified from both banks of the river and ramps the load on each transfer beam at river braced out of plane via a series of SHS railway lines. The new ticket barrier leading into Dark Neville Street within deck level, and to allow the sweeping, members, forming an inherently stable level concourse is hung from two the viaduct arches. curved roof geometry to be achieved “diagrid type” structure. In plane primary trusses that span across the Leeds station southern entrance is without the need for a secondary stability is provided via moment action lines. These were installed during due to be completed this autumn. NCE in association with Tata Steel & the British Constructional Steelwork Association 03 Structural Steelwork in Action | Special report 04 | 2015 Rapid addition Belfast Waterfront extension By Martin Cooper A steel-framed “This is a very fast-track extension to the Belfast programe, mainly due to our Waterfront conference funding obligations” and entertainment Kieran Mooney, venue will not only Belfast City Council allow it to host larger events but will boost the wider local consist of two exhibition and economy. conference spaces. Hall 1 incorporates Halls A, B, C and D, that can be used Tight spot: The site is constrained by a 2 Work is progressing at pace on the as one large 1,850m area, or neighbouring hotel and the River Lagan biggest single project in Belfast’s sub-divided via retractable walls into £150M investment programme, itself four smaller spaces.