Caunton Engineering designed the steel frame, and associated secondary steelwork consisting of chequer plate flooring and handrailing, for a new £140M extension to the Etex Plasterboard Manufacturing Facility in Bristol, as part of an expansion to double their capacity and provide additional employment to the local area.
The entire 43000m2 development, which is 525m long in total, consists of a large warehouse area, with up to 40m clear spans of hit-miss portal frame construction, a manufacturing area consisting of 45m span trusses, a 20m wide lean-to boardline structure that runs the entire length of the building, towards a two storey office of metal deck construction and the 39m high Preparation Building, containing a 5 tonne overhead crane, and adjacent Paper Store, as well as a neighbouring 33m high Calcination Building.
Sustainability was critical to the client on this project, and utilising long span portal frames and trusses ensured that the design was as efficient as possible. The 45m long trusses in the manufacturing area, for instance, were tapered to ensure an easily transportable 3m width, and were assembled from four pieces and erected using two mobile cranes on site.
The structure was designed with four movement joints between the various structures, due to the effects of temperature on the building, as well as the large differential deflection between the prep tower and neighbouring, much less high, structures.
The Preparation and Calcination buildings contain 650m2 and 1865m2 of lightweight internal mezzanine platforms respectively, formed with steel beams and chequer plate flooring, which support the complex plant within the structure, as well as to allow access for maintenance in the future, with some areas of the platforms being designed to be easily removed in the future to facilitate this. Plant loads were accurately positioned in the steelwork design model by importing the plant layout floor plan drawings at each platform level. Multiple overhead hoist beams, supported from the Boardline and Calcination structures were also designed to assist with ongoing maintenance of the plant and buildings.
A full 3D BIM coordination with other subcontractors and the client was critical to ensure there were no clashes between the structure and internal plant and services, and to ensure access to critical areas for maintenance. Regular model sharing and ongoing coordination workshops were key to meeting this aim.
Elements of the structure were subject to extremely onerous deflection limits due to the metering equipment used in the manufacturing process, and as such were a key consideration when framing the mezzanine platforms, particularly in areas where clear heights were required for access.
The Preparation and Calcination buildings were intumescent painted using a mixture of off and on-site application. Caunton were able to provide member Utilisation Ratios in fire load combinations to ensure the most efficient solution was found to meet the required fire performance, while minimising the required paint DFT’s.