Markus PÖCHTRAGER | Georg HOCHREINER
(TU Wien, Vienna, Austria)
Keywords: historical timber structure; structural model; point clouds
A fast assessment of the condition of historic timber structures is important in case of sudden damage or while renovation work. In angled and complex timber constructions surveying with tachymeter is time consuming and requires additional manual post-processing work for a modelling of the wooden beams and their joints. The technology of 3D laser scanning has evolved significantly in recent years and already allows the measurement of several hundred thousand points per second. Thus, point clouds covering an entire timber construction can be recorded quickly from several scanning positions. Yet, the manual modelling of beams from the laser scanning point clouds is still a work-intensive task. The development of automated geometric modelling from point clouds is driven forward intensively with the goal of overcoming the bottleneck in manual modelling. Developed methods like triangulated mesh generation or parametric modelling (e.g. NURBS or simple geometric solids) are finding their way into more and more application areas. A geometric fact finding about beams of the historic timber structures is required to contain at least information about the beam axis and dimensions. For a subsequent structural analysis the detection woodworking joints and the assignment of joint characteristics with respect to structural performance is of importance. The requirements for a reliable structural assessment –e.g. in terms of geometric accuracy, completeness of the geometric model as well as beam and joint characteristics– need to be discussed for different levels of detail (e.g. ideal straight beams, deformation of beams, cracks and damages on beams). While an elaboration with current manual methods for geometric and subsequent structural assessment takes weeks, our vision is to develop a method for a highly automated assessment within some hours respectively a few days. A fast automated structural assessment enables monitoring of existing structures with respect to progressive structural failure in the future.
Relevance for the conference: This work provides an approach for an automated computation of visual structural models for historical timber structures and discusses the requirements for a reliable structural assessment.
Relevance for the session: In many historical timber structures laser scans are made and plans are drawn, but the important information about the structural systems are not extracted because it is too time-consuming.
Innovation: We present innovative ideas for a highly automated computation of structural models of historic timber structures.
• Pöchtrager, M., Styhler-Aydın, G., Döring-Williams, M., & Pfeifer, N. (2018). Digital reconstruction of historic roof structures: developing a workflow for a highly automated analysis. Virtual Archaeology Review, 0. doi:https://doi.org/10.4995/var.2018.8855
• G. Eßer, G. Styhler-Aydin, G. Hochreiner: “Construction History and Structural Assessment of Historical Roofs – an Interdisciplinary Approach”; in: “Proceedings of the Structural Analysis of Historical Constructions – Anamnesis, Diagnosis, Therapy, Controls”, K. Van Balen, E. Verstrynge (Hrg.); Taylor and Francis Group, London, 2016, ISBN: 978-1-138-02951-4, S. 790 – 795.