A client engaged Polaris to assist with a feasibility study with regards to a multi-story commercial/retail building. The purpose of this feasibility study was to explore the possibility of adding additional floor levels to this existing structure. The Client was unable to locate the original construction drawings and Polaris was tasked to perform an as-built assessment of the subject structure to determine the structural layout and framing details.

Polaris experts visited the subject structure to visually observe and photographically document the as-built conditions. This included measuring framing member sizes and layouts. Ground penetrating radar (GPR) and Matterport imaging were utilized to assist with this documentation.

GPR scans were performed at representative locations on the floor slabs/beams and columns of the subject structure. The purpose of the scans was to determine the reinforcing steel layout (i.e., bar orientations and spacing). For reference, GPR is a non-destructive test method that employs high-frequency electromagnetic energy that can assess a variety of characteristics when applied to concrete structures. GPR surveys performed on concrete elements allow for the detection of embedded objects, such as steel reinforcement, pre-stressing/post-tensioning strand, and conduit, among other items. The technique involves the use of a high-frequency radar antenna which transmits electromagnetic radar pulses along a longitudinal scan at the surface of a structural element. Electromagnetic signals are optically reflected from material interfaces of varying dielectric constant along the propagation path of the wave. The reflected signals are collected by the antenna, amplified, and displayed for subsequent interpretation. The contrast between the electromagnetic properties of embedded steel and that of cured concrete provides a distinct direct reflection from the reinforcing bars. The magnitude and phase of these reflections are analyzed to determine the location of the reinforcement.

Polaris also utilized a Matterport Pro2 Camera to capture 360° images of the interior layout of the subject structure. For reference, the Matterport Pro2 Camera creates three-dimensional models using structured light (infrared) 3D sensors. It produces image quality at 4K definition. It should also be noted that spatial dimensions (within 1% accuracy) can be taken directly from the model/images. This assists with obtaining measurements and subsequently creating floor plans.

With the information/data obtained using the aforementioned imaging technology, as-built drawings and details of the subject structure were created. This information/data was critical for structural analysis purposes and allowed the client to further develop plans for adding additional floor levels to the structure.