By Heather Kossila, Senior BIM Specialist, Kraus-Anderson
In January, 2013, Matt Johnson, from Clark Engineering entered the vacant, unused Valspar building at 1101 S 3rd St. in Minneapolis, and inspected the condition of the interior. The 3-story concrete and brick building, built in 1912, along with an adjacent, 5-story timber frame and brick building, built in 1903, had been recently gutted. Now all that remained were the original exterior and core walls, the settled floors, some crooked columns, and beams of varying depth. “Perfect”, Johnson thought to himself, “just the way I like it.”
He then began to set up an instrument resembling a large camera on a tripod, and briefly looked through its lens. He fiddled with the controls, making slight adjustments in the angle and direction of the device. Curious onlookers kept a watchful eye: Was he taking pictures of the construction site?
Well, sort of.
In fact, the instrument Johnson was using is called a 3D laser scanner. 3D laser scanners analyze real-world objects and gather distance data in the form of something called a point cloud. Point clouds are a collection of millions of tiny dots, which together represent the surfaces of the objects. From these dots, 3D models can be extrapolated and analyzed, they can be manipulated or changed, and they can even be accurately (on the order of tens of micrometers) reproduced in the real world with machining and 3D printing.
So why was Johnson laser scanning the old Valspar building? Well as mentioned, it was old. The structure had settled so that even the naked eye could see that the floors weren’t level and the columns weren’t straight. The record drawings hadn’t been updated in over 100 years. Also, the new design required all MEP systems to remain in a tight space above suspended ceilings, with not a fraction of an inch protruding.
In short, an accurate existing structural model was going to be crucial to the success of the building’s MEP design, fabrication, and installation.
Scanning the entire 170,640 s.f. structure (the 3-story and 5-story buildings combined), and creating a 3D structural model took 6 weeks to complete; far less time than the traditional repetitive process of taking field measurements, marking up drawings, and turning these over to a CAD drafter to be drawn. Brad Harvey, Kraus-Anderson’s project manager for Valspar, estimates that due to the size and structural variation of the building, the old process might have added 6 months to the construction schedule.
“As a result of the scan, we learned that the floor levels were off by 8” from one end to the other, and the building was 8” longer than it should be,” Harvey stated. “Our MEP sub-contractors were able to bring the scanned building model into their software, and accurately coordinate their ducts and pipes before they fabricated them.” Ultimately, it just made the whole process go more smoothly, saving the project time and money.”
3D laser scanning may come at a sizeable capital investment, but it has the potential to garner more than twice the savings in time. As with all technology, Kraus-Anderson’s stance is to analyze a project’s challenges and determine the cost/benefit for multiple solutions.