View source for Screwfix Distribution Centre, Stoke-on-Trent

==Article in [https://www.newsteelconstruction.com/wp/wp-content/uploads/digi/2015pdf/NSCApr2015.pdf#page=20 NSC April 2015]==
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'''Steel supplies DIY merchant'''<br>
One of the country’s leading DIY and building trade suppliers is expanding one of its [[Retail_buildings#Distribution centres|distribution centres]] with steel construction.<br> 

Building work is under way to expand Screwfix’s Trentham Lakes depot in Stoke-on-Trent. Screwfix, which is part of the Kingfisher group, supplies trade tools, accessories and hardware products. The expansion will double the size of the existing facility to approximately 58,500m<sup>2</sup>; and create more than 100 full-time positions as well as safeguarding 421 existing jobs on the site. The company has also said a further 200 jobs could be created in the future.

Trentham Lakes is recognised as a premier distribution, [[Single_storey_industrial_buildings|industrial]], and mixed-use business park in Stoke-on-Trent. It is home to Stoke City FC’s Britannia Stadium, as well as a [[Residential_and_mixed-use_buildings#Hotels|hotel]], restaurants, car showrooms, and major distribution and manufacturing companies.

Screwfix Chief Executive Andrew Livingston says: “The current building has been here for around a decade and holds 40,000 different products. This expansion allows us to hold more products to help keep up with the demand. “Stoke-on-Trent is a great area for distribution because of where it is located. It allows us to deliver to stores and customers in Scotland as well as all the way to the south of the country.”

St Modwen Development Manager Euan Lindsay says the expansion had been planned for years. He comments: “It is a very exciting development considering we have been in discussion with the company since November 2011. “The investment demonstrates the fact that there is a general feeling of economic recovery and we are hopeful this will be a catalyst for other businesses coming here.”
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Working on behalf of Winvic Construction, (the company that also built the existing depot) Caunton Engineering has supplied 1,270t of structural steelwork for the project, a total that includes 200t of [[Steel_construction_products#.27Light_steel.27_sections|cold rolled steel]].

The overall [[Portal_frames|steel frame]] for the extension is a stand-alone structure with its nearest line of columns 3m away from the existing [[Retail_buildings#Distribution centres|distribution centre]]. “This means the new steel frame is structurally independent, as it gets [[Concept_design#Frame stability|stability]] from its own [[Portal_frames#Vertical bracing|vertical bracing]] systems and doesn’t impose any loads on the older building,” says Caunton Engineering Project Designer Colin Winter.

The new steel frame cantilevers from its last line of columns to within 50mm of the existing building, with [[Building_envelopes#Types of metal cladding systems|cladding]] details then creating a seamless join between the two steel frames and thereby forming one large building.

In total the extension is 18m high, 246m long and 122m wide. It is a twin propped [[Portal_frames|portal frame]] with two 61m spans. Perimeter columns are spaced at 8.5m centres, while internally columns are spaced at 17m, with every other member omitted in a ‘hit and miss’ design configuration.
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“The roof rafters have a heavily [[Concept_design#Eaves connection|haunched connection]] and were [[Fabrication#Handling and transportation|brought to site]] in 15m lengths,” adds Mr Winter. Once bolted into 30m sections two [[Construction#Mobile cranes|mobile cranes]] lifted the rafters into position in a tandem operation.

Three bays of the extension accommodate three internal [[Single_storey_industrial_buildings#Mezzanines|mezzanine]] levels. Two of these compositely formed floors cover the entire width of the building, while the third level is slightly smaller and only covers approximately two-thirds of the width.

For ease of programme, Caunton Engineering [[Construction#Steel erection|erected]] the main frame of the extension first and then proceeded to install the [[Single_storey_industrial_buildings#Mezzanines|mezzanine]] levels afterwards.

The [[Retail_buildings#Distribution centres|distribution centre]] is scheduled for completion by the end of the year.
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==[[Portal_frames|Portal frames]]==
''By Dr Richard Henderson (SCI)''<br>

In 2014, approximately 45% of the UK consumption of constructional steelwork in the UK was used in [[Single_storey_industrial_buildings|single-storey buildings]] for industrial, retail and leisure use. In this market sector, [[Portal_frames|portal frames]] are the most common structural form in pitched roof buildings. This type of building is lightweight, [[Single_storey_industrial_buildings#Resource efficient design|structurally efficient]] and familiar to UK designers in both [[Design|design]] and detailing.

The structural form offers [[Single_storey_industrial_buildings#Flexibility and adaptability|flexibility]] in building arrangement and functionality. The basic form of the single-span pitched [[Portal_frames|portal frame]] can be easily [[Portal_frames#Types of portal frames|extended]] to include multiple spans; hit and miss frames to reduce the incidence of internal columns; apex props to reduce [[Fabrication|fabrication]] and increase the roof area without using valley gutters and internal rainwater down pipes; EOT (Electric Overhead Travelling) cranes on runway beams supported on brackets or lattice columns.
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[[Portal_frames|Portal frames]] are continuous structures with [[Moment_resisting_connections|rigid joints]] which are necessary to provide [[Portal_frames#In-plane frame stability|stability in the plane]] of the structure. This feature differentiates the structural form from that with which engineers are most familiar: namely [[Braced_frames|braced frames]] of [[Simple_connections|simple construction]]. In this form of construction, beam-to-column joints are assumed to carry shear only and lateral stability is provided by [[Concept_design#Concrete or steel cores|braced or concrete cores]]. [[Portal_frames|Portal frames]] with pinned feet only require two hinges in the frame to form a mechanism in the plane of the frame. This fact means that the [[Portal_frames#Plastic analysis|plastic design]] of [[Portal_frames|portal frames]] is relatively straightforward. [[Portal_frames#Plastic analysis|Plastic design]] is efficient where strength is the limiting criterion because redistribution of load after the formation of one plastic hinge means that the material is used more efficiently than for [[Portal_frames#Elastic analysis|elastic design]].

The design of steel [[Portal_frames|portal frames]] was comprehensively covered in BS 5950-1<ref name="BS 5950-1">BS 5950-1: 2000, Structural use of steelwork in building. Code of practice for design. Rolled and welded sections, BSI</ref> which devoted a whole section to advice on [[Portal_frames|portal frame]] design. BS EN 1993-1-1<ref name="BS EN 1993-1-1">BS EN 1993-1-1: 2005, Eurocode 3: Design of steel structures. General rules and rules for buildings, BSI</ref> does not cover [[Portal_frames|portal frames]] in such depth; design principles and general application rules are provided, not detailed and exhaustive design rules. Software packages based on the detailed treatment in BS 5950-1<ref name="BS 5950-1"></ref> have been used for many years and this means most computer-designed [[Portal_frames|portal frames]] are based on BS 5950-1<ref name="BS 5950-1"></ref>.

The SCI is soon to publish a document on [[Portal_frames|portal frames]] to Eurocode 3 which will provide guidance to designers and assist software developers to write software to carry out design verification to BS EN 1993-1-1<ref name="BS EN 1993-1-1"></ref>.

{|class="wikitable" width="400"
|-
|'''Architect'''||RPS
|-
|'''Structural Engineer'''||RPS
|-
|'''Steelwork Contractor'''||Caunton Engineering
|-
|'''Main Contractor'''||Winvic Construction
|-
|'''Developer'''||St Modwen
|-
|'''Main Client'''||Screwfix
|}

==References==
<references/>

[[Category:Case studies - Single storey industrial buildings]]