Numerical Analysis of Historic Structural Elements Using 3D Point Cloud Data

Abstract

The 3D laser scanner has become a common instrument in numerous field applications such as structural health monitoring, assessment and documentation of structural damages, volume and dimension control of excavations, geometrical recording of built environment, and construction progress monitoring in different fields. It enables capture of millions of points from the surface of objects with high accuracy and in a very short time. These points can be employed to extrapolate the shape of the elements. In this way, the collected data can be developed to construct three-dimensional digital models that can be used in structural FEM analysis. This paper presents structural evaluation of a historic building through FE models with the help of a 3D point cloud. The main focus of the study is on the stone columns of a historic cistern. These deteriorated load bearing elements have severe non-uniform erosion, which leads to formation of significant stress concentrations. At this point, the 3D geometric data becomes crucial in revealing the stress distribution of severely eroded columns due to material deterioration. According to the results of static analysis using real geometry, maximum stress in compression increased remarkably on the columns in comparison with the geometrically idealized models. These values seem to approach the compressive strength of the material, which was obtained from the point load test results. Moreover, the stress distribution of the analysis draws attention to the section between columns and their capitals. According to the detailed 3D documentation, there is a reduced contact surface between columns and capitals to transfer loads.

Direct structural analysis of domains defined by point clouds

“…The stress values are in the range of 2...6 MPa, while the peak value occurs at the connection between the columns and their capitals. This is in good agreement with the values computed in [7], following the traditional measurement-to-analysis procedure, i.e. reconstructing the surface, meshing the volume and performing a finite element analysis.…”

“…5 mm was ensured to represent the highly decayed columns. More details on the measurement process can be found in [7]. Figure 16a depicts the measured point cloud, consisting of 10 7 points.…”

“…Cistern example: comparison of the maximum principal stresses computed by the FCM (left) and a commercial FEM software (right). The picture on the right is taken from[7].…”

Terrestrial Laser Scanner for the Formal Assessment of a Roman-Medieval Structure—The Cloister of the Cathedral of Tarragona (Spain)

“…Examples of it are the studies performed in the church of Santa Maria of Portonovo [15], the Cantalovo church [16], the Palazzo d'Accursio [17] (the three of them in Italy); the church of Santa Maria de Arties [18] or the Cathedral of Tortosa [19] (both in Spain), among many others. TLS surveys and displacement assessments can be also combined with other procedures of structural analysis [20], [21]. The aforementioned cases exemplify the complexity and variety of possible issues that can involve the deformation analysis in historical buildings.…”

TLS for Detecting Small Damages on a Building Façade

“…Actually, TLS have already been considered in several works for damage and cracks detection and structural analysis of infrastructures and building façades (Almac et al, 2016, Tucci et al, 2016, Guarnieri et al, 2017b, Suchocki and Błaszczak-Bk, 2019, Guarnieri et al, 2017a. Similarly to most of such previous works on damage detection with TLS, the basic principle of geometric damage detection is that of checking for variations with respect to a locally fitted (typically planar) surface (Teza et al, 2009, Kim et al, 2014, Bosché and Guenet, 2014, Wang et al, 2016, Al-Neshawy et al, 2009.…”