Currently being built for Foodstuffs (Wellington) Co-Operative Society Ltd – Palmerston North, the new Foodstuffs Distribution warehouse in Palmerston North is 32,300m2, 132m wide and 245m long, quite large as New Zealand sheds go, with a 135m x 25m canopy for delivery trucks. The development also has an administration building, a forklift/battery storage structure, a two-storey dispatch building and two substation structures. What makes it interesting is the intensity of the design team’s commitment to achieving maximum cost effectiveness.
The 3D model of the distribution warehouse, which is 32,300m2
The Structural Consulting team was led by ISP Consulting Engineers Ltd whose director, John O’Hagan, comments: “During the design stage, there was open communication between ISP, Mainzeal Construction, the main contractor, and Patton Engineering Ltd, the fabricator and erector, regarding buildability issues, detailing and costs. Usually the fabricator becomes involved only once the design documentation has been completed, but in this case the earlier involvement of the fabricator enabled us to iron our issues in advance and incorporate cost effective modifications to the design.”
Mike Patton: “Being in on the ground floor enabled us, for example, to make recommendations on splicing, so that erection would be smooth as well as safe. As soon as ISP finalised the design, Patton Engineering produced a 3D model and, once approved by the consulting engineers, it was used to generate the schedule of quantities. Pricing followed. So powerful is the software that it makes the steel detailing and workshop drawings immediately available. The fact that we are months into the project and have had no requests for variations is a huge endorsement of the design team’s work.”
Inside the Patton Engineering workshop, the lattice trusses are preassembled
ISP’s Ian Smith was on that design team, which had considered giving the warehouse a clear span. Foodstuffs weighed the cost against its operational needs and decided it could live with two lines of 356mm wide internal Universal Columns. “In the light of several geotechnical reports, we did quite a bit of work to arrive at the foundations that would be appropriate for the racking loads,” says Ian. “The final solution was mixed. Along the north-eastern side of the building, where expected settlements are low, we have specified steel screw piles under the foundation pads. Along the south-western side of the building, where the racking storage system is concentrated, we designed a large concrete pad foundation, to which the portals frames are fixed. The geotechnical engineers calculated that the foundations would settle with the slab poured and the superstructure erected. The slab is not attached to the foundations but consists of large, continuous concrete pours, post-tensioned to prevent cracking and with armoured joints kept to a minimum. The foundations are expected to settle further, once the racks are installed and fully loaded.”
ISP also gave a great deal of consideration to the thermal movement of the superstructure. John O’Hagan: “Because the whole building is linked together by primary lattice trusses, which do not have the capability of accommodating the thermal movement, we do not get the benefit of movement at the purlin connections. The roof bracing we designed as tension only. We saw this as a cost effective solution in that no additional steel was needed to transfer the compression forces since the trusses were already there. The geometry and shape of the roof bracing is quite impressive.”
Situated at 304 Roberts Line, the Foodstuffs Palmerston North warehouse is at the edge of the city boundary. Easy access to the road network means trucks can head for all points of the compass without going into the city or using its main arterial routes. It will be fully operational by November 2009.
Modern steel erection at the Foodstuffs site proceeds a large bite at a time
“The site even allows for future expansion,” says Foodstuffs Modernisation Manager, Murray Darrall. We’re very pleased with the outcome, which is the result of good synergies and the close working relationship between Mainzeal and the other players. Their commitment to this project went beyond what one has come to expect from portal frame construction.”
