From Laser Scanning to Finite Element Analysis of Complex Buildings by Using a Semi-Automatic Procedure

Abstract

In this paper, a new semi-automatic procedure to transform three-dimensional point clouds of complex objects to three-dimensional finite element models is presented and validated. The procedure conceives of the point cloud as a stacking of point sections. The complexity of the clouds is arbitrary, since the procedure is designed for terrestrial laser scanner surveys applied to buildings with irregular geometry, such as historical buildings. The procedure aims at solving the problems connected to the generation of finite element models of these complex structures by constructing a fine discretized geometry with a reduced amount of time and ready to be used with structural analysis. If the starting clouds represent the inner and outer surfaces of the structure, the resulting finite element model will accurately capture the whole three-dimensional structure, producing a complex solid made by voxel elements. A comparison analysis with a CAD-based model is carried out on a historical building damaged by a seismic event. The results indicate that the proposed procedure is effective and obtains comparable models in a shorter time, with an increased level of automation.

Segmentation of 3d Models for Cultural Heritage Structural Analysis – Some Critical Issues

“…3D documentation of CH has been extensively improved through active sensors or passive approaches but the models are not suitable for being directly exploited in FEA. Different approaches have been followed in order to generate the volumetric mesh from the acquired 3D point cloud: a) redrawing with a CAD modeller a new model using the 3D mesh (Brune et al, 2012); b) using directly the triangular mesh generated by the 3D capturing pipeline (Castellazzi et al, 2015) c) generating a volumetric mesh directly from the point cloud (Shapiro et al, 2011;Bitelli et al, 2016). One of the solutions to use realitybased 3D models results in a strong simplification of the mesh associated to a topological rearrangement of it, obtained by using retopology that involves the creation of a new topology for a 3D model.…”

A Geometric Processing Workflow for Transforming Reality-Based 3d Models in Volumetric Meshes Suitable for Fea

“…If this procedure, with all its accuracy limitations, can be applied to CH buildings because the geometry of the structure can be replicated through a CAD drawing using profiles, cannot be instead used for statues, whose geometry is more complex and that cannot be simplified through elements as bean, truss or shell, used for the modelling in FEA. The second approach has a range of slightly different methods: i) bare simplification of the triangular surface mesh before converting it in a volumetric one, that may give significant deviations between the actual shape and the simulated one (Riccardelli et al, 2014); ii) the simplified description of the shape through a set of profiles that are then discretized for generating a limited number of nodes, for creating a reliable low resolution representation of the interior and the exterior of a structure, from which produce a volumetric model (Castellazzi et al, 2015); iii) the fitting of the acquired model with a parametric model suitable to be converted in volumetric mesh (Bassier et al, 2016). Finally, the last approach does not even pass from the mesh, generating a volumetric approximation of the shape from the raw 3D cloud of points (Shapiro and Tsukanov, 1999), later compared by the same authors to the other approaches (Freytag et al, 2011;Shapiro et al, 2011).…”

Seismic Assessment of Complex Assets Through Nonlinear Static Analyses: The Fortress in San Felice Sul Panaro Hit by the 2012 Earthquake in Italy

“…The proposed procedure can take benefit from a very detailed Finite Element (FE) numerical model (see Figure 5). This latter was developed starting from the data acquired from a laser scanner survey and by means of a non-standard mesh generation procedure called CLOUD2FEM, conceived and set up by part of the authors in ( [4], [8]). Such an original procedure semi-automatically transforms 3D points cloud of complex geometries in 3D FE models, keeping low the user-time demand with respect to traditional CAD-based routines.…”