PARAMETRIC DESIGN OF TIMBER SHELL STRUCTURES by Alexandra Adelle Hinkel Cheng BA ...

154 Pages·2015·6.11 MB·English

PARAMETRIC DESIGN OF TIMBER SHELL STRUCTURES
by

Alexandra Adelle Hinkel Cheng

B.A., B.S., The University of Colorado Denver, 2012

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF

MASTER OF APPLIED SCIENCE
in
THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES
(Civil Engineering)

THE UNIVERSITY OF BRITISH COLUMBIA
(Vancouver)

October 2015

© Alexandra Adelle Hinkel Cheng, 2015
Abstract

Increasingly complex architectural geometries present new challenges for structural engineers.
Collaborative, digital workflows which integrate 3D parametric architectural models with Finite
Element Modelling software grant structural engineers a higher degree of geometric versatility
and influence during the preliminary design phase. Through integrated parametric design models
– also labelled “co-rationalized” – structural engineers may not only easily respond to rapid
model variations and unusual assemblies, but also inform the building design from inception.
This thesis presents an example of a project executed in a co-rationalized manner through
architectural and structural collaboration, using both digitally-integrated and analog models, for
the design and construction of solid timber shells structures using Cross-Laminated Timber
(CLT) panels. By exploring a co-rationalized design process, timber engineering details are
identified and integrated into the architectural model, and the role of structural engineer takes an
active rather than reactionary role in the preliminary design stages.
The result of this process using integrated parametric models was the design, fabrication, and
assembly of a folded plate wall prototype and three CLT panels with double curvature. This
research demonstrates how collaboration and integrated modeling enables the realization of the
architectural versatility that mass-timber has to offer, and the efficacy which co-rationalized
design and integrated models can bring to orthodox and unusual structures alike. As a
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consequence, this research serves as a precedent for structural detailing-based generative
architecture and collaborative work in the future.
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Preface

This thesis describes my structural engineering research made in part in service of a larger,
collaborative research project “Shell Structure in Wood” in partnership with the School of
Architecture and Landscape Architecture and the Centre for Advanced Wood Processing at the
University of British Columbia. Support was provided by Forest Innovations Investment through
the Wood First Act (Government of British Columbia 2009) . The project was carried out by
myself in collaboration with graduate architecture students under the supervision of Prof.
Tannert, Prof Meyboom, and Prof. Neumann. Owing to the interdisciplinary nature of the
project, roles of each researcher in the team can be broadly sketched as follows:
Primary Masters Student researchers from SALA:
 Thomas Gaudin: Primary Parametric Modelling, Diagrams, Architectural Conceptualization
 Jessica Hunter: Wood Fabrication, Architectural Conceptualization
 Roy Cloutier: Wood Fabrication, Parametric Modelling, Diagrams, Renderings,
Architectural Conceptualization
Supporting Masters Student researchers from SALA:
 Sarah Maria: Photographic Documentation
 Nicole Tischler: Photographic Documentation, Fabrication
Masters Student researcher from Civil Engineering:
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 Myself: Integration with FEM, Structural Parametric Modelling, Structural Research,
Design, Definition of Constraints, Fabrication, Diagrams, Architectural Conceptualization
In addition, parts of this research have been published in collaboration with the aforementioned
as follows:
 Neumann O, Hunter J, Cheng A, Gaudin T, Tannert T, Meyboom AL (2015)
TimberShell: Large Scale Timber Shell Structure Prototypes. Association for Computer-
Aided Design in Architecture (ACADIA) Computational Ecologies: Design in the
Anthropocene, October19-25, Cincinnati, USA.
 Hunter J, Cheng A, Tannert T, Neumann O, Meyboom AL (2015) Extending the
Perception of Wood: Research in Large Scale Surface Structures in Wood. Association
for education and research in computer aided architectural design in Europe (eCAADe)
33rd Annual Conference, September 16-18, Vienna, Austria.
 Cheng A, Tannert T (2015) Comparative Study on Timber-based Hybrid Systems for
High-rise Construction. ASCE Structures Congress, April 23-25, Portland, USA.
 Cheng A, Meyboom AL, Gaudin T, Neumann O, Tannert T (2015) Large Scale Wood
Surface Structures. International Conference on Architecture and Civil Engineering (ACE
2015), April 13-14, Singapore, Singapore.
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Table of Contents

Abstract .......................................................................................................................................... ii 
Preface ........................................................................................................................................... iv 
Table of Contents ......................................................................................................................... vi 
List of Tables ................................................................................................................................ xi 
List of Figures ............................................................................................................................. xiii 
Acknowledgements .................................................................................................................... xix 
Dedication ................................................................................................................................... xxi 
Chapter 1: Introduction ................................................................................................................1 
1.1  Overview of Project .......................................................................................................... 1 
1.2  Architectural Demand ....................................................................................................... 2 
1.3  Renaissance of Structural use of Timber .......................................................................... 3 
1.4  Historical Context ............................................................................................................. 4 
1.5  3D Parametric Building Design ........................................................................................ 6 
1.5.1  Parametric Modeling Concepts ................................................................................... 6 
1.6  Approaches to Structural Design of Parametric Architecture ........................................ 11 
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1.6.1  Overview ................................................................................................................... 11 
1.6.2  Precedents, Methods, and Tools ............................................................................... 12 
1.6.3  Co-Rationalized Structural Engineering ................................................................... 17 
1.7  Research Objectives ........................................................................................................ 18 
1.8  Methodology ................................................................................................................... 20 
1.8.1  Overview ................................................................................................................... 20 
1.8.2  Project Team ............................................................................................................. 22 
1.8.3  Tools ......................................................................................................................... 23 
Chapter 2: Design of Shell Structures using Mass-Timber .....................................................25 
2.1  Cross-Laminated Timber ................................................................................................ 25 
2.1.1  Laminated Wood Composites ................................................................................... 25 
2.1.2  Mechanical Properties of CLT .................................................................................. 27 
2.1.3  Analytical Methods for Modeling CLT Bending Stiffness ....................................... 32 
2.1.3.1  Overview ....................................................................................................... 32 
2.1.3.2  Mechanically-Jointed Beams Theory (“γ-method”) ..................................... 32 
2.1.3.3  Shear Analogy Method ................................................................................. 35 
2.1.4  Cross-Grain CLT Properties ..................................................................................... 36 
2.2  Timber Panel Joinery ...................................................................................................... 40 
2.3  Self-Tapping Screws ....................................................................................................... 43 
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2.4  Defining Plates and Shells .............................................................................................. 45 
2.5  Approximating Plate and Shell Behaviour with Frame Elements .................................. 47 
2.6  Folded Plates ................................................................................................................... 48 
2.6.1  Precedent Folded Timber Panel Structures ............................................................... 51 
2.7  Doubly-Curved Timber Shells ........................................................................................ 54 
2.8  Discussion ....................................................................................................................... 58 
Chapter 3: Developing Integrated Parametric Models ............................................................60 
3.1  Software Concept ............................................................................................................ 60 
3.2  Rhinoceros and Grasshopper .......................................................................................... 62 
3.3  Third-Party Plugins ......................................................................................................... 63 
3.3.1  Python-scripted Customized Components ................................................................ 64 
3.4  Integration with FEM Analysis ...................................................................................... 65 
3.5  Genetic Algorithm Evolutionary Solvers for Optimization ............................................ 68 
Chapter 4: Integrated Parametric Modelling of Folded CLT Plates ......................................70 
4.1  Approach ......................................................................................................................... 70 
4.2  Possible Spans and Fold Angles ..................................................................................... 71 
4.2.1  Scripting Shear Analogy into a GhPython Component ............................................ 71 
4.2.2  Modeling a CLT Panel Defined with Shear Analogy in Grasshopper ...................... 74 
4.2.3  Varying Fold Angle to Determine Maximum Span .................................................. 74 
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4.3  Minimum Panel Dimensions and Connection Design .................................................... 75 
4.4  Effective Stiffness of CLT Panels with Cross-Grain ...................................................... 79 
4.4.1  Comparing Analytical Methods ................................................................................ 80 
4.4.2  Implementation in Grasshopper ................................................................................ 85 
4.5  Prototyping and Assembly .............................................................................................. 88 
4.5.1  Available Panel Sizes ................................................................................................ 90 
4.5.2  Machining Limitations .............................................................................................. 91 
4.5.3  Available Fasteners ................................................................................................... 91 
4.6  Prototype Fabrication ...................................................................................................... 95 
4.7  Discussion ....................................................................................................................... 96 
Chapter 5: Integrated Parametric Modelling of Double-Curvature CLT .............................98 
5.1  Approach ......................................................................................................................... 98 
5.2  Geometry of Doubly-Curved CLT Panels ...................................................................... 98 
5.3  Preliminary Integrated Model of a Doubly-Curve d CLT Panel .................................. 102 
5.4  Fabrication of Doubly-Curved CLT Panels .................................................................. 104 
5.4.1  Preparation .............................................................................................................. 104 
5.4.2  Screw-Fastened Doubly-Curved CLT Panel .......................................................... 105 
5.4.3  Adhesively-Bonded Doubly-Curved CLT Panel .................................................... 107 
5.5  Prototype Evaluation .................................................................................................... 109 
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5.6  Discussion ..................................................................................................................... 115 
Chapter 6: Conclusions .............................................................................................................116 
6.1  Summary of Work ........................................................................................................ 116 
6.2  Future Research ............................................................................................................ 116 
6.3  Conclusion .................................................................................................................... 117 
Bibliography ...............................................................................................................................119 
Appendix A Joining Options for CLT Panels ........................................................................ 128 
A.1  Overview ................................................................................................................. 128 
A.2  Assemblies with Self-Tapping Wood Screws ......................................................... 131 

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