Algorithm for the analysis of the geometric properties of cross-sections of timber beams with lack of material from LIDAR data

Beams, pillars or bars of solid timber structures, although having a nominal regular form, frequently have irregular sections along their length, that in many times represent an important lack of material in the structural member. All the changes in the cross section of the beam must be considered in any kind of strength calculation and the protocols for the structural health monitoring. The principal aim of this investigation is the development of an algorithm for the automatic analysis of the geometric properties of the cross-sections of timber beams, in order to detect any lack of material and irregular cross-sections. The developed algorithm is based on 2D projection techniques and Alpha-shape. Finally, the repercussions in the strength of the beam are evaluated. A series of tests on synthetic beams and on real wooden beams have been done to verify the correct function of the algorithm. The difference between the results obtained by the algorithm and the results obtained by contact instruments reached an average of error of 3 %. The results obtained demonstrate that the algorithm proposed is adequate for the automatic analysis of the geometrical properties in the section of timber beams with a lack of material or irregular section.

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