Digital workflow for the accurate computation of the geometric properties of bamboo culms for structural applications

Abstract

Bamboo is one of the most promising sustainable construction materials due to the large endemic natural reserves prevalent in the Southern Hemisphere. However, industrialised materials, such as concrete, steel and aluminium have overshadowed the application of natural bamboo culms, due to the high-quality assurance achieved over decades refining the production processes of structural elements manufactured from the former. As a result, the physical, geometric and mechanical properties of these industrialised structural elements are quantifiable, predictable and in agreement with international standards. This research presents the details of a digital workflow to quantify the inherent geometric variability of bamboo culms as part of a new quality assurance process for this natural structural element. This workflow relies on the use of a mid-range, commercially available structured-light 3D scanner to accurately capture a point cloud of the bamboo geometry and generate a corresponding polygon mesh. Digital models of three different bamboo species were validated through comparison with key physical measurements finding that the adoption of these digital models can significantly improve the accuracy and efficiency of manual methods due to the complex irregularities found in bamboo culms. This work demonstrates the benefits of adopting a non-destructive, reverse-engineering approach to quantify the geometric properties of bamboo compared to traditional tools and methods. Overall, this research shows the potential of digital technologies to support the adoption of this natural material allowing for the re-assessment of design workflows and providing an opportunity for bamboo to compete with industrialised materials.

Digital analysis of the geometric variability of Guadua, Moso and Oldhamii bamboo

“…The objective of this work is to carry out a comprehensive analysis of the geometric variability of three different bamboo species based on the application of 3D scanning technologies and reverse engineering principles. This study follows a previously developed approach [28] for the digitisation of bamboo culms based on initial 3D polygon-mesh models [29]. These mesh models are further processed into lighter Non-uniform rational basis spline (NURBS) models [30] from which geometric properties are computed and analysed.…”

“…The specific details of the scanning and processing parameters are shown in Table 3 and Fig. 2b shows the final triangulation of the point cloud to create a 3D polygon-mesh of the scanned culm The average accuracy of the scanned polygon mesh was 1% for cross sectional dimensions and 1/1000 th of the culm length compared with manual measurements [28]. The scanner was operated with a laptop Dell XPS 15 equipped with an Intel i7-6700HQ CPU @ 2.66GHz, 16GB of installed memory and a dedicated video card Nvidia GTX GeForce 960m with 4GB of memory whilst the processing of point cloud was carried out in a work station Dell Precision with an Intel Xeon E5-1620v3 CPU @ 3.5GHz, 32GB of memory and a dedicated video card Nvidia Quadro K2200 with 4GB of memory.…”

An innovative digital workflow to design, build and manage bamboo structures

“…The organic shape of an individual culm (irregular cross-section and longitudinal spatial curvature) and irregular anatomical arrangement of its constituent materials (parenchyma and sclerenchyma cells) [3,38], increase the complexity for the culm to be represented in a digital environment. Moreover, the variability of geometric, physical, and mechanical properties within culms makes them unique [28,29,39], as opposed to standard, which not just prevents the formal utilization of bamboo culms in the building industry, but also their integration into digital platforms. This gap requires a holistic digital approach that tackles the challenge associated with the organic nature of bamboo culms while integrating them into modern platforms to properly manage the quality and reliability of bamboo structures.…”

“…The intensive geometry measurement relies on 3D scanning technology, to rapidly digitize the irregular shape of individual culms, combined with computational processing that automatically extracts cross-section properties at given intervals [28,39,42]. This digitization procedure (Figure 1) has been validated (in terms of model accuracy) and further used in research to help understand the structural behavior of bamboo culms [40][41][42].…”

Working with Uncertainties: An Adaptive Fabrication Workflow for Bamboo Structures

“…The success of integration requires tolerance of each material group to be within a specified range, e.g., the Chinese code GBT51233-2016 and GB50755-2012 set the maximum error to ±6.4 mm in length and ±3.2 mm in width for prefabricated timber plates and ±1 mm for steel components. Industrialized materials such as steel, concrete and engineered wood are used more frequently in construction because their geometrical and mechanical properties are more predictable (Lorenzo and Mimendi 2019). Although natural bamboo is a great candidate for building construction, more effort needs to be taken to control its tolerance.…”