Control of Construction Quality by a Terrestrial Laser Scanner: Example of Steel Frame Building

Quality control during construction is important for many reasons. For one, it can be used for the evaluation and assessment of the as-built condition. The latter state of the construction can be used for making small adjustments of other elements comprising the future structural system. For example, it can be used for assessing the pile's final location, twist, and inclination after driving the pile into the ground. A possibility of small deviations is quite common in this case. In addition, the imperfections captured during the construction can be used in forensic studies or other reconnaissance efforts of the structural failures, if any. A terrestrial laser scanner can capture an object's exposed surface with high accuracy. By measuring the duration of travel of a laser beam emitted by the scanner, it can estimate locations of the object's points in space. A set of these points is commonly called a point cloud. The paper's main objective is to evaluate an approach for measuring imperfections in installation of steel structural members. The approach is based on utilization of a terrestrial laser scanner. As a typical example of structural members, a wide flange steel beam is studied herein. The approach is based on the analysis of numerous horizontal slices of the beam's point cloud. A tight bounding box is computed for each slice and its location is compared against other horizontal slices. Based on this analysis, the beam's basic dimensions, twist and inclination are obtained. The paper provides an approach for a quantitative assessment of the beam's deviations from its as-drawn configuration.