When retailer The Warehouse wanted to expand its already-massive distribution center in Rolleston, New Zealand, Holmes Consulting employed a truly innovative solution. The job demanded accurate measurement of the existing structure, plus 3D modelling of the planned expansion so the old and new structures could integrate smoothly. Holmes used 3D laser scanning data to generate point cloud models, then used the data to create a 3D model in Tekla Structures.
Earthquakes make for an uncertain start for a building
The Warehouse’s distribution center on the South Island of New Zealand was constructed as recently as 2002. However, following substantial business growth by retailer, the center--already the size of about seven soccer fields--was deemed too small.
This prompted an expansion project to add 15 000 m2 of storage and distribution space, plus 2 000 m2 of extra container canopies, new racking and conveyor systems, and extra yard and parking areas.
The facility stores goods for distribution to The Warehouse’s 25 South Island stores, and every day it is occupied by two shifts of up to 75 workers each. Throughout any construction project, the facility needs to remain fully productive, which demands maximum efficiency from the construction process.
The distribution center was shaken with the major earthquakes and thousands of aftershocks experienced in the area from September 2010 onwards. Before any expansion work could take place, a thorough forensic examination of the existing building was required to determine how the quakes had impacted the center’s structure and position. And while Holmes Consulting held the original plans for the building, it was possible that the as-built distribution center differed from the design as a natural result of the construction process.
Starting with a structurally sound base
As the original designers of the distribution center, Holmes Consulting were the logical choice to plan the expansion. A New Zealand-based organization of engineering experts, they could also apply their expertise in solving the seismic challenges. Jeff Matthews, business manager for Holmes Consulting, was responsible for final sign-off of the project.
“First we needed to make sure the building was structurally sound and still positioned as indicated in our 2D models,” said Matthews. “So we contracted surveyors to scan the end frame of the building using 3D laser scanners.”
Holmes Consulting has utilized 3D scan data for over six years. Initially they captured the data to develop as-built models of historic or heritage buildings before strengthening work. Now they rely on 3D data for many diverse projects, including complex industrial buildings where no as-built information exists but alteration, extension, or strengthening is required. For The Warehouse project, Holmes contracted a local surveying company to perform the scans.
Following the as-built scan, the point cloud models generated showed definite movement--not a lot, but enough to create unpleasant surprises during construction and cause costly delays. “We integrated this critical information into the documentation right from the start,” said Jeff. “It meant we didn’t need to modify key connections on site during construction.”
Holmes used the 3D data to model all of the building’s structural steel (existing and new) in Tekla Structures, a building information modelling (BIM) software.
The Tekla software works with all materials, including steel and concrete, to create models for the most complex structures.
From the Tekla model, the Holmes team produced all documentation for the project, including general arrangement (GA) drawings for consent and full shop detailing. The enlarged views of complex areas necessary for GA drawings were easily created from the dense 3D data.
Tekla software generates a variety of file formats to support information flow between construction stakeholders. On the Warehouse project, an IFC file was exported to Autodesk Revit BIM software to produce all architectural documentation. For maximum workflow efficiency, Tekla models can be exported into Revit almost seamlessly.
The model also enabled Holmes to accurately detail all of the structure steel for the project. “Accurately detailing all required steel enabled us to create a materials schedule,” said Jeff. “So our Tekla model gave us certainty of materials cost and time on site.”
A streamlined construction sequence
Holmes Consultancy’s innovative use of 3D point clouds and exceptional results secured them Best Industrial Project at the Tekla Global BIM Awards 2016.
Their process realized efficiencies and savings on the Warehouse project from very early on. “Using point cloud analysis saved us an enormous amount of time because we didn’t have to convert our original 2D model to 3D,” said Matthews.
Overall, their work ensured a streamlined and precise construction sequence that allowed productivity at the distribution center to continue throughout the expansion.
Their client, The Warehouse, now has updated drawings for the original structure, an accurate set of models for the new extension, and usable information for maintenance and future building extension. And Holmes engineers will be quick to utilize 3D scan data in future BIM projects.