Assessing the Performance of Bamboo Structural Components

Assessing the Performance of Bamboo Structural Components

ASSESSING THE PERFORMANCE OF BAMBOO STRUCTURAL COMPONENTS by Michael J. Richard Bachelor of Science, Worcester Polytechnic Institute, 2008 Master of Science, Worcester Polytechnic Institute, 2009 Submitted to the Graduate Faculty of The Swanson School of Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Pittsburgh 2013 UNIVERSITY OF PITTSBURGH SWANSON SCHOOL OF ENGINEERING This dissertation was presented by Michael J. Richard It was defended on June 5, 2013 and approved by Melissa Bilec, Ph.D., Assistant Professor, Civil and Environmental Engineering John Brigham, Ph.D., Assistant Professor, Civil and Environmental Engineering Khosrow Ghavami, Ph.D., Full Professor, Civil Engineering, PUC-Rio C. Drew Armstrong, Ph.D., Associate Professor, Architectural Studies Dissertation Director: Kent A. Harries, Ph.D., Associate Professor, Civil and Environmental Engineering ii Copyright © by Michael J. Richard 2013 iii ASSESSING THE PERFORMANCE OF STRUCTURAL BAMBOO COMPONENTS Michael J. Richard, Ph.D. University of Pittsburgh, 2013 Bamboo has been a traditional construction material in many regions for centuries. The rapid growth and maturation rate of bamboo as well as its good strength properties and global accessibility make it a promising non-conventional building material resource. However, due to limited standardization and design criteria, bamboo has often been relegated to non-engineered and marginally-engineered construction. The current study assesses the performance of full-culm structural bamboo components and appropriate standard material and member test methods. A brief overview is given to the motivation for the study of structural bamboo, placing the work in its social context, followed by background on the properties of bamboo and the structural applications of the material as well as the pathway to its further standardization and utilization. Experimental and analytical studies are conducted focusing on the tensile, flexural, buckling, and environmental sustainability performance of full-culm bamboo components. Standard bamboo tension tests are carried out to investigate the test interferences associated with the functionally graded fiber distribution across the culm wall thickness. Tension specimens oriented in both the radial and tangential directions are considered in order to isolate the effects of the fiber gradation both on test results and experimental methodology. Recognizing longitudinal splitting induced by flexure as a dominant limit state, modified standard bamboo flexural tests are performed to investigate the development of a standard test procedure for this limit state, which involves a mixed-mode longitudinal splitting failure in the flexural element. Flexural testing considers two iv test configurations and three difference species of bamboo. Results of modified full-culm tests are compared with smaller clear bamboo flexural specimens taken from the culm wall as well as standard or proposed tests for pure mode I and pure mode II failure components. The experimental buckling capacity of single-culm and multiple-culm bamboo columns is studied as further understanding of column strength is critical to the construction of more robust and potentially multiple-story bamboo structures. Finally, in an effort to quantify the perceived sustainability benefits of bamboo, the environmental impacts of multiple-culm bamboo columns are compared with structurally comparable timber and steel alternatives in a comparative midpoint life cycle analysis. v TABLE OF CONTENTS NOMENCLATURE ............................................................................................................... XVII ACKNOWLEDGMENTS ......................................................................................................... XX 1.0 INTRODUCTION ........................................................................................................ 1 1.1 THE GROWING SOCIO-ECONOMIC GAP .................................................. 2 1.2 HOUSING: A FUNDAMENTAL RIGHT YET GLOBAL CHALLENGE .. 3 1.3 ADEQUATE SHELTER AND NATURAL DISASTERS ............................... 5 1.4 THE STRAIN ON GLOBAL BUILDING RESOURCES ............................... 9 1.5 SUSTAINABLE DEVELOPMENT WITH BAMBOO ................................. 15 1.6 SCOPE OF DOCUMENT ................................................................................. 17 2.0 BAMBOO AND ITS STRUCTURAL APPLICATIONS ....................................... 20 2.1 BAMBOO AND ITS RESOURCES................................................................. 21 2.1.1 Bamboo Taxonomy and Classification ........................................................ 21 2.1.2 Bamboo Anatomy, Structure, and Growth ................................................. 22 2.1.2.1 The Bamboo Culm .............................................................................. 23 2.1.2.2 The Rhizomes ...................................................................................... 25 2.1.2.3 Bamboo Growth and Flowering ........................................................ 27 2.1.3 Bamboo Resources ......................................................................................... 30 2.1.4 Bamboo Harvesting and Seasoning.............................................................. 32 vi 2.1.4.1 Bamboo Propagation and Plantations............................................... 33 2.1.4.2 Bamboo Harvesting and Seasoning ................................................... 35 2.1.4.3 Bamboo Treatment and Preservation ............................................... 36 2.1.5 Mechanical Properties of Natural Bamboo ................................................. 39 2.1.5.1 Modulus of Elasticity .......................................................................... 40 2.1.5.2 Flexural Strength ................................................................................ 40 2.1.5.3 Compression Strength ........................................................................ 41 2.1.5.4 Tensile Strength................................................................................... 41 2.1.5.5 Shear Strength ..................................................................................... 42 2.1.5.6 Commentary on Bamboo Material Properties ................................. 43 2.2 STRUCTURAL APPLICATIONS OF BAMBOO ......................................... 43 2.2.1 Bamboo Structures ........................................................................................ 44 2.2.2 Bamboo Jointing Techniques ....................................................................... 49 2.2.3 Hazard Mitigation and Disaster Relief through Bamboo Structures ....... 53 2.2.4 Engineered Bamboo Products ...................................................................... 55 2.2.5 Composite Bamboo Products and Systems ................................................. 56 2.3 THE PATH TO STANDARDIZATION ......................................................... 57 2.3.1 Current Bamboo Standards ......................................................................... 58 2.3.2 Improving Standardization .......................................................................... 61 3.0 INHERENT BENDING IN BAMBOO TENSION TESTS .................................... 64 3.1 BAMBOO TENSILE STRENGTH.................................................................. 65 3.2 INHERENT BENDING AND ROTATION OF TENSION SPECIMENS .. 68 3.3 EXPERIMENTAL PROGRAM ....................................................................... 73 vii 3.3.1 Specimens and Fabrication ........................................................................... 74 3.3.2 Testing Apparatus ......................................................................................... 76 3.3.3 Instrumentation ............................................................................................. 77 3.4 EXPERIMENTAL RESULTS ......................................................................... 79 3.4.1 Failure Modes ................................................................................................ 79 3.4.2 Tensile Strength ............................................................................................. 82 3.4.3 Experimental Strain Profiles ........................................................................ 86 3.4.4 Experimental Stress Profiles ......................................................................... 92 3.4.5 Experimental Elastic Modulus Profile ......................................................... 93 3.5 CONCLUSIONS ................................................................................................ 94 4.0 PERFORMANCE OF BAMBOO FLEXURAL COMPONENTS ........................ 97 4.1 BAMBOO FLEXURAL BEHAVIOR ............................................................. 97 4.1.1 Bamboo Flexural Behavior ........................................................................... 98 4.1.2 Bamboo Shear and Splitting Behavior ...................................................... 103 4.1.2.1 In-Plane Shear (Mode II Failure) .................................................... 105 4.1.2.2 Bamboo Splitting (Mode I and Mixed-Mode Failures) ................. 106 4.2 EXPERIMENTAL PROGRAM ..................................................................... 113 4.2.1 Bamboo Species and Test Locations .......................................................... 113 4.2.2 Bowtie Tests.................................................................................................

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