View source for Bond Street development, Chelmsford, Essex

==Article in [http://www.newsteelconstruction.com/wp/wp-content/uploads/digi/NSCApri2016digi/index.html#/12/ NSC April 2016]==
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'''Essex gets retail therapy'''<br>
A large [[Braced_frames|steel-framed]] retail and [[Leisure_buildings|leisure development]] is set to invigorate Chelmsford city centre.<br> 

The Bond Street retail and [[Leisure_buildings|leisure development]] will transform Chelmsford city centre when it opens later this year, adding new traditional shopping streets that will integrate with the rest of High Street area. Nestled on the banks of the River Chelmer, the scheme forms phase two of a much larger city centre regeneration scheme that previously included the [[Construction|construction]] of three blocks of riverside [[Residential_and_mixed-use_buildings#Residential buildings in urban areas|apartments]] (see [http://www.newsteelconstruction.com/wp/flexible-steel-forms-riverside-apartments/ NSC November 2007]).

This latest development comprises a large John Lewis (the first in Essex) anchor department store, three other mixed [[Retail_buildings|retail blocks]], a multi-screen digital [[Leisure_buildings#Theatres and auditoria|cinema]], landscaped public spaces and a 275-space underground [[Car_parks|car park]] that covers nearly half of the project’s entire footprint.

Steel [[Construction|construction]] is playing a leading role in the building of the Bond Street scheme, as all of the structures are [[Braced_frames|steel-framed]] with the exception of the [[Leisure_buildings#Theatres and auditoria|cinema]] block, which is a hybrid building. It consists of a two-level concrete lower part, which will house restaurants, supporting a [[Braced_frames|steel-framed]] upper level accommodating the [[Leisure_buildings#Theatres and auditoria|cinema]] complex.

The site was previously occupied by a large city centre surface [[Car_parks|car park]] and so, when work began early last year, there was no demolition required. Instead a large earthmoving programme kicked off the development as the underground [[Car_parks|car park]] was excavated.

Working in areas that had previously been excavated and piled, [[Design|design]] and build steelwork contractor Caunton Engineering began the [[Construction#Steel erection|erection]] process with the John Lewis store. The 11,148m<sup>2</sup> John Lewis store consists of three trading levels – ground, first and second. For ease of programme this [[Braced_frames|steel-framed]] structure was the first to be [[Construction#Steel erection|erected]].
{{#image_template:image=File:Bond_Street_development_Chelmsford-2.jpg‎|align=left|wrap=true|caption=The [[Braced_frames|steel-framed]] [[Leisure_buildings#Theatres and auditoria|cinema]] sits atop a concrete podium|width=300}}
“It’s the furthest from the site’s access point and so it made our job less challenging to work on this building first and then work our way out of the site by way of the other buildings,” says Caunton Engineering Contract Manager Adrian Downing. Caunton’s [[Construction#Steel erection|erection]] sequence was also dictated by the groundworks programme, as excavation and piling work had to precede the steelwork. Another reason behind this store being [[Construction#Steel erection|erected]] first is the fact that it is the development’s anchor and potentially it will need the longest fit-out programme before it is ready to open.

The store is based around a 9m × 10.2m [[Concept_design#Floor grids|grid pattern]] for all of its levels except the uppermost retail floor where alternate rows of columns have been omitted to give a more [[Retail_buildings#Flexibility| open-plan area]].

Forming a pitched roof over this top retail floor are two rows of 21m-long × 1,800mm deep [[Trusses|trusses]]. Caunton brought the [[Trusses|trusses]] to site in two pieces and then after [[Construction#Site bolting| bolting]] them together they were lifted into place using one 50t-capacity [[Construction#Mobile cranes| mobile crane]].

Block One, which houses 10 double-height retail units and is structurally attached to the John Lewis store forming one large [[Braced_frames|braced frame]], was the next structure to be [[Construction#Steel erection|erected]]. The same 9m × 10.2m [[Concept_design#Floor grids|grid]] is also used to form Block One as well as the adjacent Block Two [[Retail_buildings|retail building]]. This [[Concept_design#Floor grids|grid]] was deemed to be the most efficient for both the [[Retail_buildings|retail buildings]] and the underground [[Car_parks|car park]], which sits beneath all of these blocks.

The majority of the columns forming the [[Car_parks|car park]] extend up into the retail floors. However, there are a number of instances where this is not possible. For example, many of the Block One and Block Two columns above basement level have been relocated into partition walls to create an [[Retail_buildings#Flexibility|open-plan shop area]]. This means a number of large transfer beams have been installed at ground floor level. Typically these transfer beams are 914UB [[Steel_section_sizes|section sizes]] of various weights, and some span up to 18m and support two columns up to roof level.

An uncovered pedestrian mall separates John Lewis/Block One from Block Two, while another mall, positioned at right angles to the first, separates these buildings from the [[Leisure_buildings#Theatres and auditoria|cinema]] structure. “The position of these malls and the fact that they do not run perfectly straight also meant that we had to install a number of transfer structures within the ground floor area,” says Caunton Engineering Project Engineer Gavin Christie.
<gallery widths=300px heights=250px> 
Image:Bond_Street_development_Chelmsford-4.jpg|View of the [[Leisure_buildings#Theatres and auditoria|cinema]] and River Chelmer from the John Lewis store
Image:Bond_Street_development_Chelmsford-5.jpg|The upper floor of the John Lewis store features a larger open-plan [[Concept_design#Floor grids|grid pattern]]
</gallery>
The [[Leisure_buildings#Theatres and auditoria|cinema]] was possibly the most complex [[Braced_frames|steel frame]] to be [[Construction#Steel erection|erected]] and required more than 1,000 individual sections. Sitting atop two concrete levels, the steelwork is based nominally on a 6m-perimeter [[Concept_design#Floor grids|grid]], although this changes slightly to accommodate the structure’s shape that incorporates a bull-nose feature at one end and a rounded point at the other.

“The [[Construction#Typical erection rates|piece count]] was so high because there is a complicated cantilevering roof feature that wraps around the bull-nose,” explains Caunton Engineering Senior Structural Engineer Colin Winter. “It slopes and widens to a maximum depth of 3m and required a lot of [[Single_storey_industrial_buildings#Secondary steelwork|secondary steelwork]].”

The steelwork for the [[Leisure_buildings#Theatres and auditoria|cinema]] is tied into a couple of stair [[Concept_design#Concrete or steel cores|cores]], as installing bracing was not an option due to the lack of areas in which to put it. Both ends of the [[Leisure_buildings#Theatres and auditoria|cinema]] feature mezzanine levels, while in-between the five [[Leisure_buildings#Theatres and auditoria|cinema]] auditoria vary in size with the largest requiring roof rafters with a span of 16m.

The steel [[Construction#Steel erection|erection]] programme was completed by the end of February and the last structure to be [[Construction#Steel erection|erected]] was retail Block Three. This stand-alone [[Braced_frames|braced frame]] houses further double-height outlets and is separated from Block Two by the [[Car_parks|car park]] ramp and the development’s service yard.

The Bond Street development is scheduled to open before Christmas.

==Time consuming elevations==
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The project’s elevations consist of a number of different and complicated [[Facades_and_interfaces#Types of façade systems|cladding types]] including masonry, [[Facades_and_interfaces#Insulated render|render]], stone and aluminium panels.

The [[Retail_buildings|retail units]] along the mall and Bond Street also feature an 800mm wide coping stone at parapet level. These are generally offset from main columns and this led to an intricate secondary steelwork framing system being required to support the coping stone and also the [[Facades_and_interfaces#Types of façade systems|cladding system]].

“As each [[Retail_buildings|retail unit]] has a unique set-out, the [[Design|design]] of these elements was a time-consuming process. Utilising the combined architect and steelwork 3D model proved extremely beneficial in speeding up [[Design|design]], by aiding set-out and helping to visualise support requirements,” explains Caunton Engineering Project Engineer Gavin Christie.

{|class="wikitable" width="400"
|-
|'''Architect'''||WCEC Architects
|-
|'''Structural Engineer'''||Mott MacDonald
|-
|'''Steelwork Contractor'''||Caunton Engineering
|-
|'''Main Contractor'''||Bowmer & Kirkland
|-
|'''Main Client'''||Aquila
|}

[[Category:Case studies – Retail buildings]]