View source for Moberly Leisure Centre and Prime Place, Kensal Rise, London

==Article in [http://www.newsteelconstruction.com/wp/wp-content/uploads/digi/NSCMay2017digi/index.html#/18/ NSC May 2017]==
{{#image_template:image=File:Moberly_Leisure_Centre-1.jpg‎|align=right|wrap=true|caption=Cellular beams form the Centre’s roof|width=400}}
'''[[Trusses|Trusses]] span sporting haven'''<br>
A series of storey-high [[Trusses|trusses]] create the [[Residential_and_mixed-use_buildings#Podium structures|transfer deck]] between a leisure centre and a [[Residential_and_mixed-use_buildings|residential scheme]] in London.<br> 

Replacing a number of old Victorian buildings, North Westminster will soon have a new community sports centre offering an array of [[Leisure_buildings|leisure facilities]] including two pools and an eight-court badminton hall. Known as the Moberly Leisure Centre, the project, which is currently under [[Construction|construction]] in Kensal Rise, west London, also includes a substantial residential element known as Prime Place, which consists of 56 rooftop [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]] and 15 townhouses.

Steelwork is playing a central role in the job as the leisure centre is a large [[Braced_frames|steel-framed]] structure that supports the light gauge steel-framed [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]] above. Explaining why a steel solution was chosen for the project’s design, AECOM Principal Engineer Lloyd Bickle says: “We needed [[Leisure_buildings#Ability to span long distances|long spans]] for the sports areas and steel [[Steel_construction_products#Cellular beams|cellular beams]] offered the most efficient solution. Meanwhile, parts of the roof need to act as a [[Residential_and_mixed-use_buildings#Podium structures|transfer structure]] spanning over the relatively large open areas of the leisure centre to support the load bearing walls of the [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]] above. Steel [[Trusses|trusses]] can span these distances picking up the required load with the necessary stiffness.”

Work on the project began during April last year (2016) with main contractor Willmott Dixon removing a large amount of asbestos, prior to demolishing the existing buildings and clearing the site.

Steelwork [[Construction#Steel erection|erection]] kicked off towards the end of last year, and has progressed in a sequential manner starting at the southern end of the site. Explaining why this sequence was necessary, Willmott Dixon Construction Manager Stuart Rooney says: “When the steelwork [[Construction#Steel erection|erection]] began, we were still doing groundworks as well as pouring the concrete for the basement and pool areas on the north side of the site. Working this way kept the project on schedule.”
{{#image_template:image=File:Moberly_Leisure_Centre-3.jpg‎|align=left|wrap=true|caption=Model of the main steelwork, excluding the [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]]|width=300}}
The leisure centre is a two-storey structure, albeit with a 9m-high floor-to-ceiling height in most areas. It is a large [[Braced_frames|braced frame]] with [[Braced_frames#Vertical bracing|bracing]] located along elevations and within the [[Concept_design#Concrete or steel cores|core]] areas. Interestingly, all of the leisure centre’s main [[Concept_design#Concrete or steel cores|cores]] were changed from concrete to steel in order to speed up the programme.

The ground floor area contains a 25m-long six-lane swimming pool, a learner pool with a moveable floor, a multi-use hall for boxing and gymnastics, changing rooms and a café, as well as the main entrance and reception. This floor also includes a [[Single_storey_industrial_buildings#Mezzanines|mezzanine]] level which will accommodate community and meeting rooms.

One part of the scheme, positioned along the main Chamberlayne Road elevation, is however a separate and independent steel frame. Containing a 225m<sup>2</sup> retail unit with two [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]] above, this area has been designed as an independent structure so that it can be isolated from the leisure centre’s adjoining first floor gym to mitigate any potential [[Acoustics|acoustic]] transfer. As well as the gym, the first floor of the leisure centre contains three exercise/dance studios and an eight-court sports hall with seating for 500 spectators.
{{#image_template:image=File:Moberly_Leisure_Centre-4.jpg‎|align=right|wrap=true|caption=View of the completed Centre with the [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]] above|width=250}}
Westok [[Steel_construction_products#Cellular beams|cellular beams]] have been installed to form the [[Leisure_buildings#Ability to span long distances|long span]] column-free areas on the ground and first floors. Spanning the pools and the gymnastics hall, a series of 15.3m-long × 900mm-deep beams, each weighing 2.3t, has been used. Spanning the first floor sports hall, and forming part of the leisure centre’s roof, is a series of 38m-long × 1.261m-deep beams, each weighing 15t. These beams are cranked at both ends to form a feature mansard roof.

The long span areas of the project are all centrally-positioned within the overall scheme. Forming an L-shape around these areas and extending along the two main elevations on Chamberlayne Road to the west and Kilburn Lane to the north, the [[Braced_frames|steel frame]] is formed by a more traditional beam and column structure. This part of the structure accommodates changing rooms and other facilities that do not need large open-plan spaces.

Above this L-shaped part of the structure sit the project’s [[Residential_and_mixed-use_buildings#Light steel framing|light gauge steel-framed]] apartments and their roof gardens. The units are a mixture of one and two-bedroom [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]], containing either one or two bathrooms. Rising to a maximum height of four levels, the [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]] are in a stepped formation falling to a single level of units in the south and east of the project.
{{#image_template:image=File:Moberly_Leisure_Centre-5.jpg‎|align=left|wrap=true|caption=[[Residential_and_mixed-use_buildings#Light steel framing|Light gauge steel]] is [[Construction#Steel erection|erected]] to form the [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]]|width=250}}
There are 30 different configurations of apartment and consequently their column lines seldom match the regular 6m × 6m column [[Concept_design#Floor grids|grid pattern]] in the leisure centre. As well as the [[Residential_and_mixed-use_buildings#Light steel framing|light gauge framework]], a total of 30t of hot-rolled steel columns have been used to form the [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]].

To support the irregular [[Residential_and_mixed-use_buildings#Light steel framing|light steel frames]], a [[Residential_and_mixed-use_buildings#Podium structures|transfer structure]] has been designed to sit between the leisure centre and the residences. Formed with a series of 4.6m-deep [[Trusses|trusses]], they vary in length, with the longest measuring 19m and weighing 14t. The deep [[Trusses|trusses]] also create useable space within their depth, a de-facto second floor of the leisure centre, where plant equipment will be accommodated.

“The majority of the project’s steelwork was [[Construction#Steel erection|erected]] using the site’s two [[Construction#Tower cranes|tower cranes]], but the [[Trusses|trusses]] were too heavy and had to be installed using a 350t-capacity [[Construction#Mobile cranes|mobile crane]],” says Mifflin Construction Project Director Nigel Jones. The [[Trusses|trusses]] had to be [[Fabrication#Handling and transportation|brought to site]] in small sections and then assembled on the ground, with each one requiring nearly 1,000 bolts.

The majority of the project’s steelwork will not be on view within the completed scheme. The only exceptions are the [[Steel_construction_products#Cellular beams|cellular beams]] and a series of perimeter [[Steel_construction_products#Structural hollow sections|CHS columns]] that form the two main elevations beneath the [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]].

The project is due to be complete by Spring 2018.

==Transfer [[Trusses|trusses]]==
''By David Brown, SCI''<br>
{{#image_template:image=File:Moberly_Leisure_Centre-2.jpg‎|align=right|wrap=true|caption=[[Trusses|Trusses]] support the rooftop [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]]|width=400}}
The steel [[Trusses|trusses]] used at the Moberly leisure centre are storey height [[Trusses#Warren truss|Warren trusses]], carrying plant loading in addition to the [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]] above. The development of the truss solution illustrates some of the [[Trusses#Aspects of truss design for roofs|design aspects]] to be carefully considered. Design loading might be thought to be straightforward, but in reality can often be a moving target as the design develops. At Moberly leisure centre, the [[Leisure_buildings#Flexibility and adaptability|flexibility]] of a steel solution meant that the final solution of [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]] above could be revised, but this also meant that the loads were changing – perhaps a common challenge in the fast-moving world.

Deflection is always important in every structure and often checked under variable actions only. With [[Residential_and_mixed-use_buildings#Podium structures|transfer trusses]], the deflection due to permanent actions may have a significant effect on the supported structural elements and so is a situation to be carefully investigated. At the leisure centre, the impact of the [[Construction|construction]] programme had to be considered, as some [[Construction|construction]] was proceeding prior to all the permanent loads being applied to the [[Trusses|trusses]]. The fit-out below the [[Trusses|trusses]] was to be completed before the [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]] above were [[Construction#Steel erection|erected]], so details to accommodate the anticipated deflection had to be incorporated in the fit-out below the [[Trusses|trusses]].

Given the span and depth of the [[Trusses|trusses]], welded [[Fabrication|pre-fabrication]] in sections and [[Construction#Site bolting|bolted assembly on site]] was necessary, as would be the case for all very large elements. [[Design|Design]] and detailing should be then affected by the need to bolt sections together – a typical first choice is to provide [[Moment_resisting_connections#Bolted end-plate splices|end plate type splices]] at a node point in the compression chord (at a location also restrained out of plane), and [[Moment_resisting_connections#Bolted cover plate splices|cover plate type splices]] in the tension chord. This assumes that reversal will not take place – which is unlikely with [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]] on top of the [[Trusses|trusses]]. Generally, [[Preloaded_bolting|pre-loaded assemblies]] are likely to be used in the tension splices to avoid any unexpected additional deflection.

The [[Trusses|trusses]] at the Moberly leisure centre were analysed assuming pinned joints, which is to be recommended for simplicity. Even without applied moments, the joints in a transfer truss will probably involve considerable local strengthening. If the truss members (including the internals) are [[Steel_construction_products#Standard open sections|UC sections]], a good starting position is to consider that the axial load in an element is in proportion to the cross sectional area. A single UC flange will therefore be carrying approximately 40% of the axial load in the member, and it can be helpful to consider how this load is transferred to the chord. As the flange of the internal member is generally perpendicular to the web of the chord, local strengthening is probably inevitable.

A longer discussion on the use of [[Trusses|trusses]] appears in the [http://www.newsteelconstruction.com/wp/wp-content/uploads/digi/NSCMarch17digi/index.html#/23/ March issue of NSC]

{|class="wikitable" width="400" 
|-
|'''Architect'''||Roberts Limbrick
|-
|'''Structural Engineer'''||AECOM
|-
|'''Steelwork Contractor'''||Mifflin Construction
|-
|'''Main Contractor'''||Willmott Dixon
|-
|'''Main Client'''||Westminster City Council / Prime Place
|}

[[Category:Case studies – Leisure buildings]]
[[Category:Case studies – Residential and mixed-use buildings]]