Control in the Process of the Building Construction by Means of Stationary Terrestrial Laser Scanning

Abstract

This study will give a contemporary method for Quality Assurance or as-build during the construction of a building in Sofia, R. Bulgaria by using High Definition Survey (HDS) or more known as terrestrial Laser Scanning. Analyses were done on concrete casted elements (Floors, Ceiling Slabs and Columns) for the first eight floors which were already constructed during the time of field measurements. As a reference - data are obtained from the original design in native AutoCAD format, while field data were acquired by using 3D laser Scanners and they are represented in a form of Point Cloud. All data (design and measured) are acquired in local coordinate system and were later georeferenced in to the already established object coordinate system. The study will show the workflow for data preparation, post processing, and the results from 3D Inspection and Analyses. All tasks were implemented by two survey crews within 10 working days (four days for field work and 6 days for post processing analyses and reporting). During the laser scanning a total of 3 679 440 634 points were surveyed form 368 stations. After the post processing the number of points was reduced to 2 515 520 148 with relative accuracy after registration of individual scan worlds of +/- 3-4 mm. The accuracy for the data transformation in to the object coordinate system is +/- 7.5 mm. In order to have better data visibility and understanding of the deformations and displacements casted concrete elements were inspected separately floor by floor where ceiling and floor slabs were inspected in 1D (Z direction) while columns were inspected in 2D - (XY) inspection for the position. Thus some will say that the results are within accuracy limits of the classical measuring techniques we should not forget the fact that the percentage of inspected elements/surfaces is more than 95%.