UNIVERSITY OF MICHIGAN NORTH QUAD PROJECT

GPR PROJECT January 2009

The University of Michigan in Ann Arbor is building a new dorm for future student housing at the intersection of State and Huron. A problem arose on the project when down on the lower level of the building the existing openings in the walls for HVAC and fire protection piping apparently were not big enough for the amount of pipe required. There became an immediate need for new openings in the walls to allow for the overflow piping. The problem with making new openings the size that was needed was that the structural engineers did not want the rebar to be cut through in the process. This would hurt the integrity of the walls, which were an eye-popping 36-42 inches thick.

GPRS was contacted to come out and x-ray the walls to layout the rebar locations. Although GPRS does not actually use concrete x-ray, people refer to our services as such. Utilizing ground-penetrating radar over traditional x-ray allows for safer, quicker, and more accurate results. Locating the rebar would allow the engineers and contractors to make an informed decision on where to cut and where not to cut. Because the project was utilizing BIM (Building Information Modeling) 3-D software, the construction managers decided to take the GPR findings and have them planted into the buildings 3-D module (see Fig.1)

Figure 1

The picture above shows the rebar findings implanted into the concrete wall of the buildings 3-D module software. The software shows exactly how the building was designed and constructed in the field.

Figure 2

GPRS service technician John Kessinger does a scan along a wall to identify the rebar locations. GPRS can scan not only floor slabs but also vertical walls and even ceilings when needed.

GPRS can provide their findings in real time and will plot the location directly onto the surface. Our accuracy is dependent on what is being located but rebar and post-tensioning can be within ¼ inch horizontal and ½ inch vertical. Underground utilities can be located within 3 inches horizontal and 6 inches vertical in most cases. Call John Kessinger for your next project in Michigan at 734.377.4551 or by email at john.kessinger@gp-radar.com