View source for Kings Dock car park, Liverpool

==Article in [http://www.newsteelconstruction.com/wp/wp-content/uploads/digi/NSCApril2020digi/pubData/source/NSCApril2020digi.pdf#page=20 NSC April 2020]==
{{#image_template:image=File:Kings_Dock_car_park-1.jpg|align=right|wrap=true|caption=Visualisation of how the completed car park will look|width=400}}
'''Steelwork creates safe parking'''<br>
Clad in order to reference the city’s maritime past, a new [[Car_parks|multi-storey car park]] in Liverpool has been built using a [[Braced_frames|steel frame]] as the material offered the most cost-effective programme. 

Containing 1,452 spaces, a new multi-storey car park is due to open at Liverpool’s Kings Dock later this summer, replacing a structure that suffered irreparable fire damage on New Year’s Eve 2017.

Constructed on an adjacent plot to the older structure, the new [[Car_parks|car park]] is 150m-long × 33m-wide, and including ground floor and roof, it has eight levels. It is a [[Braced_frames|steel-framed]] structure, based around a standardised column [[Concept_design#Floor grids|grid pattern]] of 7.5m along its perimeter, with one line of internal columns giving the car park two spans of 16m-long. The steel beams support [[Steel_construction_products#Decking for floors|metal decking]] and a 160mm-thick concrete topping to form the [[Floor_systems#Composite slabs|composite floors]].

“We looked at all framing solutions, but went for a [[Braced_frames|steel-framed]] option, with [[Floor_systems#Composite slabs|metal decked floors]] and precast cores as it was the most cost-effective method for this project,” says Willmott Dixon Operations Manager Peter Mason. The damaged and, consequently unusable, car park left a large hole in the city’s car parking availability and Liverpool City Council wanted a replacement to be built as quickly as possible as the car park will not only serve the nearby Liverpool Arena and the waterfront, but also the wider city centre. For this reason, [[The_case_for_steel#Speed of construction|speed of construction]] was another important consideration that had to be taken into account when choosing the frame’s material. It was decided that steelwork offered the fastest programme for the project team.

Main contractor Willmott Dixon started work on the new [[Car_parks|car park]] during the early part of 2019, having previously worked on the demolition of the adjacent damaged structure.

“One of the key drivers for us was to have a steelwork contractor on board that could cope with the car park’s [[Fabrication|fabrication]] complexities,” adds Mr Mason. “All of the 16m-long beams are precambered to create the 1:6 fall that each floor has from both perimeters to the of the centre of the structure. Draughtsmanship was fundamental and Leach Structural Steelwork has proven to have been up to the task.”

As well as each floor having two cambers they also slope in the other direction as the [[Car_parks|car park]] has been designed as a Vertical Circulation Module (VCM), which is said to offer a more efficient solution for confined city plots. This [[Design|design]] contains no external ramps as all of the circulation is via slopes within the floors, which in turn creates more parking spaces.
<gallery mode="packed" heights=250px> 
Image:Kings_Dock_car_park-2.jpg|[[Construction#Steel erection|Steelwork erection]] nears completion
Image:Kings_Dock_car_park-3.jpg|Large [[Trusses|trusses]] form the access and exit points on the ground floor
</gallery>
<br>
The steelwork programme was completed during a five-month programme, using two 60t-capacity [[Construction#Mobile cranes|mobiles cranes]] and two [[Construction#Steel erection|erection]] gangs. They installed the steelwork in 10 phases – five on each side of the structure – with each phase built to the full height of the [[Car_parks|car park]]. The perimeter columns are spaced at 7.5m centres, which was deemed to be the optimum distance to create sufficiently wide parking bays for most vehicles. To this end, there are three × 2.5m-wide parking bays between each set of columns. Alongside the main steel frame [[Construction#Steel erection|erection]], Leach Structural Steelwork also [[Fabrication|fabricated]] and installed the impact barriers and mesh screens. The barriers are [[Fabrication|fabricated]] from two [[Steel_construction_products#Structural hollow sections|CHS members]], which are interlinked by channels. They were [[Fabrication#Handling and transportation|delivered to site]] in fully-[[Welding|welded]] 7.5m-long elements.

Within the footprint of the [[Car_parks|car park]], there are five precast [[Concept_design#Concrete or steel cores|cores]], two large ones containing both lifts and stairs, and in between three smaller stair cores. The precast cores were chosen for their speed of installation, but they offer no [[Concept_design#Structural options for stability|structural stability]] to the main frame steelwork, as this is all derived from [[Braced_frames#Vertical bracing|cross bracings]] located at either end of the car park and in between the internal line of columns.
{{#image_template:image=File:Kings_Dock_car_park-4.jpg|align=right|wrap=true|caption=The car park's [[Building_envelopes|cladding]] has motifs that are a reference to the city's maritime history|width=250}}
[[Fabrication#Handling and transportation|Delivering the steel]] to the site was a fairly routine procedure as the surrounding roads are wide enough for most trucks and the site initially had plenty of laydown space. However, many pieces of steelwork had to go on one more journey than they would ordinarily expect.

All of the project’s steel has been [[Metallic_coatings#Hot-dip_galvanizing|hot-dip galvanized]], a process which was necessary because of the [[Corrosion_of_structural_steel#The corrosion process|atmospheric environment]] that can be expected due to the site’s proximity to the River Mersey estuary. “Ordinarily, the 16m-long beams would have been [[Fabrication#Handling and transportation|delivered to site]] after they’d been [[Metallic_coatings#Hot-dip_galvanizing|galvanized]]. However, we had to return them to our [[Fabrication|fabrication]] yard in order to cut holes in them to accommodate the car park’s [[Sprinklers_in_UK_fire_codes|sprinklers]]. This work couldn’t have been done prior to [[Metallic_coatings#Hot-dip_galvanizing|galvanizing]] as it would have damaged the steelwork,’ explains Leach Structural Steelwork Quantity Surveyor Patrick Rostron.

Aside from the main beams, the largest single elements in the [[Car_parks|car park]] are a series of [[Trusses|trusses]] that form two large openings along the ground floor level, one for vehicle access and the other for exiting. As ground floor columns had to be omitted to form these spaces, 15m-long × 3m-high transfer [[Trusses|trusses]] were installed to form a bridge at first floor level and support the reinstated columns lines for the floors above.

The [[Trusses|trusses]] were [[Fabrication#Handling and transportation|brought to site]] in individual sections, with each member installed during the [[Construction#Steel erection|erection]] programme. This proved to be a time-consuming process, especially as the [[Trusses|trusses]]’ internal members are connected via gusset plates, some of which have up to 48 bolts. This led the project team to change one of the [[Trusses|trusses]] to a 1.8m-deep [[Steel_construction_products#Plate girders|plate girder]] as this was quicker to install.

The steelwork will be left [[Visually_expressed_structural_forms|exposed]] and in full view within the completed structure, while from the outside, the frame will be visible through the [[Building_envelopes|cladding]]. Summing up, Leach Rhodes Walker Architects Managing Director Christian Gilham explains: “This is an engineering structure and so it was important to have the steelwork as a feature, which can be glimpsed through punched holes in the aluminium cladding. “With reference to Liverpool’s maritime heritage, the cladding is also adorned with Schooner motifs, while other areas of the structure are clad with red/brown brickwork, which is a further nod to the city’s industrial past and the area’s surviving warehouses.

{|class="wikitable" width="400"
|-
|'''Architect'''||Leach Rhodes Walker Architects
|-
|'''Structural Engineer'''||Hill Cannon
|-
|'''Steelwork Contractor'''||Leach Structural Steelwork
|-
|'''Main Contractor'''||Willmott Dixon
|-
|'''Main Client'''||Liverpool City Council
|}

[[Category:Case studies – Car parks]]