Civil + Structural Engineer Media
June 1, 2021
Reynolds Polymer Technology, Inc., an acrylic specialist company based out of Colorado, faced the challenge of precisely measuring, documenting, and communicating the production and installation of a custom shark tank window in Georgia Aquarium’s expansion project. In order to do so, the precision cast-in-place concrete rebates needed to be measured in a three-dimensional grid from a set of opposing arches – a daunting task considering the safety of the aquarium’s visitors being a liability.
Sure, the rebates could have been measured by drawing a complex grid and measuring points with a tape measure. But this 35,000 lb. (15,875 kg) acrylic viewing window required a ¼” (6 mm) site tolerance. If incorrectly measured, the space between the acrylic window and the concrete rebate could be too small or too large. If too small, thermal movement could fracture the window due to insufficient expansion and contraction allowances. If too large, the engineers would need to reassess the variance for potential sealant issuers, causing costly remedial work on site.
The window had to fit, and the measurements had to be quick, cost-effective, and extremely precise.
The concrete rebates have two opposing arches, one horizontal at 300” (7,820 mm) long, and the other vertical at 480” (12,190 mm) long. Obtaining an accurate three-dimensional grid, precise enough to manufacture the viewing window to tolerance, would have taken days while offering measurements exceeding the manufacturing tolerances.
The use of a standard tape measure can easily decrease accuracy of up to ½” (12.7 mm) over 33 ft (10 m) due to sag, temperature, and twist of the tape. By using a tape measure, the contractor would have added at least another ½” (12.7 mm) to the existing tolerance. This would have created significant fitment issues with the window.
Reynolds Polymer selected the Leica Geosystems 3D Disto to accurately measure the rebates expertly fabricated and poured by Brasfield & Gorrie. The Leica Geosystems 3D Disto is a unique tool that captures three-dimensional measurements and projects points for 2D layout applications. The speed and precision of the 3D Disto brings unprecedented efficiency to applications such as creating CAD templates; 3D visualization and navigation; capturing as-built measurements; building information modeling (BIM); and highly accurate measurements for custom fabrications.
The Leica 3D Disto uses your own Windows device to operate, with intelligent software making it possible. This software controls the tool, automatically carrying out all complicated calculations in the background while only supplying the relevant information needed. Users can see directly what has been measured, either as a live image supplied by the integrated camera, or as a three-dimensional model.
The 3D Disto measured to within 1/16” (1.58 mm) accuracy by projecting the image it saw on the accompanying wireless touchscreen tablet. The robotic feature of the 3D Disto allowed it to shoot all required points from the opposing concrete rebate arches within an hour. The measurements were then loaded in a file within 15 minutes and directly emailed from the jobsite to the product engineer in Colorado.
Here, the engineer was able to overlay the 3D measurements into his CAD program. The process was both fast and highly accurate and gave confidence to Reynolds Polymer that the window would fit exactly as needed.
The custom acrylic window was lifted through a special framed opening in the roof of the Georgia Aquarium and place onto the concrete rebates, where it fit with precision and within tolerance.
With this process, Georgia Aquarium, Brasfield & Gorrie, and Reynolds Polymer have provided an exceptional viewing window to the shark exhibit without concern for project delays or cost overruns.
Prefabricated or assembled building products, whether they be the acrylic window at Georgia Aquarium or granite countertops for residential kitchens, create challenges to ensure that the components fit into the site-built frames and irregular spaces of partially build structures.
Highly accurate site measurements, especially for these expensive custom fabrications, ensure these puzzle pieces fit together well and without costly rework or damage. Regardless of large or small tolerances, the assurance of the 3D Disto accuracy eliminates guesswork and costly errors and reduces time used to compensate for inaccuracies.
Read more – https://csengineermag.com/the-shark-habitat-challenge/