MRP - Bamboo Fiber-Reinforced Composites

Bamboo Fiber-Reinforced Composites A Proposed Structural Material for Tall Building Construction

Bamboo Fiber-Reinforced Composites:

A Proposed Structural Material for Tall Building Construction By Mark Sellers A research project presented to the University of Florida Graduate School of Architecture in partial fulďŹ llment of the requirements for the degree of Master of Architecture Chair: Dr. Nawari Nawari Co-chair: Dr. Frank Bosworth

“Even the smallest seed of an idea can grow. A single idea from the human mind can build cities.

An idea can transform the world and rewrite all the rules.�

-Christopher Nolan

ACKNOWLEDGMENT

I would like to express my profound gratitude to my chair, Dr. Nawari Nawari, and to my co-chair, Dr. Frank Bosworth, for their guidance in this research. Both have provided indispensable feedback and support.

I acknowledge my fellow classmates of the Orlando CityLab Department of Design, Construction, and Planning. I am grateful for all the enjoyable times we shared as we travelled together to complete this challenging journey.

I wish to give a special thanks to my wife for her love, support, and patience. I am very fortunate to have a wife who supports and encourages me to continuously push forward and to be my very best.

I dedicate this work to my son who is a constant reminder of the beautiful world in which we live.

ABSTRACT

This research project explores the use of bamboo fiber-reinforced composites in the construction of tall buildings. The goal of this research is to determine if this material has the potential to be used as a primary structural material for tall building construction. In addition, this material shows great promise to be more environmentally sustainable with faster construction times and lower construction costs.

It begins by investigating tall buildings and the effect that they have on the environment.The need for tall buildings arises from the need for increasing urban density necessary to accommodate population growth.

Currently, half of the world population is living in urban environments and within the next 25 years, is expected to increase to nearly 80%. Increasing density in cities is now widely accepted as necessary for achieving more sustainable urban environments to reduce energy consumption and thus combat climate change. Other added benefits that tall buildings have include reducing vehicle travel times and creating an opportunity for open spaces like playgrounds, plazas, parks, and other communi-

ty spaces, of which can improve air quality and visual appeal of a city.

The research investigates the three primary materials used in tall building construction today, steel, wood and concrete. Buildings represent the largest energy-consuming sector in the economy, consuming over one-third of the world’s energy and are responsible for approximately one-third of global carbon emissions. Concrete production alone represents more than five percent of all carbon dioxide emissions. Steel is also a poor choice due to its high-embodied energy and low thermal performance. Steel production is also among the largest energy consumers in the construction industry since the manufacture of steel involves many energy intensive processes.

Wood is typically the best principal material available for building structures with respect to embodied energy and carbon emissions because wood requires less fossil fuel-based energy to produce and produces far less greenhouse gas emissions than the manufacture of concrete or steel; however, wood products require the cutting down of vast numbers of trees leading to deforesta-

tion and ultimately lowering Earth’s ability to remove the excess carbon dioxide from the atmosphere.

This study replicates a case study completed by SOM in 2013. They replaced specific reinforced concrete members with mass timber, resulting in a code compliant and sustainable method of construction. This study builds on the SOM investigation by replacing the mass timber elements with Bamboo Fiber-Reinforced Composite (BFRC) material. Available research data for the material was sufficient to estimate member sizes, material weight, and carbon emissions. The results indicate that BFRC has potential as an alternative to concrete, steel and wood for the construction of tall buildings. This conclusion is based on the assumption that the proper amalgamation of polymer matrix and natural fibers will yield BFRC possessing the best properties of each component yielding a high quality sustainable building material made from a plant that grows well and is available in most parts of the world.

TABLE OF CONTENTS

Introduction

1

The Need for Tall Buildings From the Beginning Reduce Travel Times Prevent Urban Sprawl Preserve Open Spaces Environmental Quality Population Growth Human Impact

3 3 4 4 5 6 6 7

A Need for Alternative Materials Embodied Energy Concrete Steel Wood Tall Wood Buildings Deforestation Global Warming

9 10 10 10 11 12 13 15

Time for Change What are Bamboo Fiber-Reinforced Composites A Brief History of Bamboo Bamboo as a Building Material Bamboo Fiber-Reinforced Concrete Bamboo Strength Global Distribution of Bamboo Chemical Composition and Structure Material Research Epoxy Based Bamboo-Fiber Reinforced Composites Void Content Polypropylene Based Bamboo Fiber-Reinforced Composites Timber Tower Research Study

17 17 17 18 18 18 19 19 19 21 21 22 23

Design Approach Structural System Member Size Calculations Construction Sequence Foundation and Substructure Column Spacing Floor-to-Floor Height Floor Framing Strategy with the Core Sustainability and Carbon Footprint Fire Protection Techniques Structural Considerations Related to Fire Increase Member Size Charring Charring Rate Insulation Method Connections Fire Sprinklers Fire Resistant Polymers Geographic Distribution of Bamboo in the World Bonn Challenge Sustainable Developments Needed in Florida Florida Sustainable Communities Demonstration Project Green Works Orlando

23 24 29 29 29 29 29 29 29 30 30 30 31 31 32 32 32 33 34 34 35 36 36

Conclusion

37

Glossary of Terms

41

List of Figures

45

References

47

INTRODUCTION

This study investigates the use of Bamboo Fiber-Reinforced Composites (BFRC) in the construction of tall buildings. By researching current construction materials, techniques and the growing demand for tall buildings, justifications are made as to why this material is needed. BFRC do not currently exist; however, the need for such a material is real in order to build sustainably and meet the demands of a changing world.

For more than a century, urban skylines around the world have been shaped by tall buildings made almost exclusively from concrete and steel. Architects and engineers continue to explore the potential of concrete and steel and have a considerable understanding of their performance in a variety of environments around the world.

These materials have enabled buildings to grow to heights that are continually being pushed to new limits. Concrete and steel are excellent materials for tall buildings, however, new technologies today may allow us to build tall structures faster, cheaper, and with less environmental impact than ever before. This is a unique moment in architectural and building engineering history

with shifting world needs having us question whether our building material choices of past centuries will be the best choices in the centuries to come. This project introduces a major opportunity for systemic change in the building industry that may permanently alter the way we think about the built environment.

Historically, wood has been used as a primary construction material to make everything from buildings to weapons. Wood is strong, warm, and easy to work with; however, it comes with one major flaw, trees take an estimated 20 to 30 years to reach adequate size for harvesting. With the invention of concrete and steel, modern urban environments were poured, not hammered, into place, as wood was slowly demoted as a primary building material in dense urban settings. As we gain a better understanding about the materials with which we build, new technologies become available that allow us to bring wood back into urban areas. Technologies such as Cross Laminated Timbers (CLT), Laminated Veneer Lumber (LVL), and Glued Laminated Wood (Glulam) are wood products

that are stronger and less flammable than traditional wood products, which allows for the construction of tall buildings up to ten stories. Architects and engineers are now envisioning wood use for structural components for even taller buildings up to 30 or 40 stories. Wood as a construction material may manifest itself as a sustainable choice, however, deforestation continues to degrade the planet and magnify the effects of global warming.

Just as the automobile industry, energy sector, and most other industries have seen innovations that provide new and improved methods of fabrication, the building industry must seek innovation in the fundamental materials with which we choose to build. It is more important today than ever before that we find solutions for our rapidly urbanizing world in order to provide housing for the billions of people who will live in our cities in the coming decades.

For the first time in history the majority of the human population is living in urban areas, and this percentage continues to grow. Global population has doubled since 1950 and is projected to continue its rapid

1

growth, surpassing 10 billion in the next 35 years. The United Nations estimates that by the year 2050 roughly 85% of the world population will live in urban environments.

Currently, our cities do not have the buildings or the infrastructure to support this kind of growth. Increases in urban population and a lack of environmental concern have created many negative environmental impacts, including inefficient land use, transportation problems, and increasing levels of carbon dioxide emissions. If left unchecked, these effects will continue to degrade the environment at an accelerated pace. Dense urban environments characterized by tall buildings can accommodate population growth while also being environmentally sustainable, but only if the development takes place responsibly.

This project describes a new structural system made from BFRC that represents the first significant challenge to concrete, steel, and wood structures.The proposed system is made from a material with very unique properties and has the potential to revolutionize the building industry. The particular characteristics that BFRC possess arise from the characteristics of its individual components. Bamboo is one of the most significant, diverse, and robust building materials ever provided to man by nature and is readily available, renewable, durable, and

2

strong. Fibers found within many species of bamboo possess tensile strengths comparable to that of steel. By placing these fibers within a polymer matrix, the tensile strength can be utilized to create nearly any building component imaginable. Polymers are a material consisting of any of a wide range of synthetics that are malleable and therefore can be molded into objects of almost any shape or size. Polymers are an ideal material to be used in the construction industry due to the many benefits the material offers including its resistance to fire and rot, lightweight, low cost, and color variety. The main disadvantage of polymers relates to its low tensile strength, which is remedied by using the fibers of the bamboo plant within the core of the material. Melding bamboo within a polymer matrix makes BFRC an exemplary building material that possesses both high tensile strength and compressive strength as well as resistance to fire, insects, rot, and ultraviolet light. It is also moldable which ultimately opens up an array of new possibilities in the field of architecture.

This study is the beginning of a path to realizing built projects using a material that harnesses and utilizes unique characteristics from both a man made substance as well as a natural made fiber. The demand for tall buildings will continue to grow

along with the ever-increasing global population; however, to build sustainably and to begin reducing carbon dioxide emissions, a new material is needed for the construction of tall buildings.

THE NEED FOR TALL BUILDINGS From the Beginning Building construction began with the purely functional need for a controlled environment to moderate the effects of climate.

Temporary shelters allowed human beings a way to adapt to a wide variety of environments and thereby populate nearly every part of the globe. Early building materials were perishable, such as leaves, branches, and animal hides. These human shelters were quite simple and perhaps lasted only a few days or months. As time went on, however, the structures evolved into more durable buildings and allowed people to stay in one place for long periods of time, eventually forming cities.

Up until the past two centuries cities looked very different from the way they look today. Urban landscapes tended to be flat and uniform in pattern, with the exception of monuments, temples, and cathedrals, which towered above everything else in the city. Increased urban land values, the invention of the elevator, and the development of structural steel, gave rise to the skyscraper.1 Attempts were made every so often to construct tall buildings for residential or office use, however, the result of which was frequent building collapse due to structural

failure. Because of this, laws were passed to limit the heights for which a building could be built. In the 1870s, steel frames became available, gradually replacing the weaker combination of cast iron and wood previously used in construction.2 Steel frames were able to carry the weight of more floors, so walls became simply cladding for the purpose of insulating and adorning the building. This development, which included applying hollow clay tiles to the steel supports, resulted in a fireproof steel skeleton and also permitted movable interior partitioning, which allowed for more flexibility for office building use. This new method of construction reduced the thickness of walls, increased floor space, and enabled increases in height. Freed from the constraints of traditional construction, the facade could now be opened with windows to maximize the amount of daylight reaching the interior of the building.3 Tall buildings today use steel or concrete almost exclusively, for two reasons. First, with some limited exceptions, non-combustible materials are required by most building codes for buildings greater than four stories tall. Second, steel and concrete have higher material strengths than masonry and wood, making them a natural choice

for tall buildings. These factors have generally limited wood use to low-rise buildings.4 Recently, developments in mass timber technology are overcoming these challenges. Mass timber products such as cross-laminated timber (CLT) can be built up using small pieces of dimensional lumber and structural adhesives to achieve panels as large as one foot thick and 40 feet long.

These panels can be used as floors and shear walls with structural sizes necessary to support a tall wooden building.5 Wood members of this size have an equally important characteristic; they behave like heavy timbers in a fire and form an insulating char layer, which protects underlying material.

The charring behavior is predictable and preserves a portion of the member’s structural strength, making performance based fire design of mass timber structures possible.6 The structural and fire engineering advancements of mass timber have made recent multi-story wood buildings possible.

However, the sustainability of wood seems to be an equally important consideration in the resurgence of multi-story timber buildings.7

3

Reduce Travel Times In general, tall buildings are recognized as an efficient type of compact development within an urban setting that helps reduce travelling distances and carbon emission.

Compact developments are needed due to the outward expansion of cities into the suburbs resulting in ever increasing travel times, energy consumption, and CO2 emission.8 Tall buildings can accommodate many more people with a much smaller building footprint than with low-rise building on the same amount of land. Researchers have concluded that one of the best ways to reduce carbon emission is to build compact

Figure 1 Heavy congestion during rush hour in Shanghai, China.

4

places where people can accomplish more and travel less.9 Compact developments have been shown to reduce driving from 20% to 40% and at the same time allow the opportunity for open spaces like playgrounds, plazas, parks, and other community spaces, of which can improve air quality and visual appeal of the city. Besides the impact on the city skyline, tall buildings thus influence the city fabric at a much deeper level than simply increasing density.10 Cities such as Hong Kong and Singapore, where clustering of tall buildings is common, are among the world’s most transport-energy efficient, and environmentally friendly cities

in the world.11 Figure 1 shows the result of too many people depending on vehicular transportation to move from one place to another.

Prevent Urban Sprawl Urban sprawl, a pattern of uncontrolled development around the periphery of a city, is an increasingly common feature of the built environment in the United States and other industrialized nations. (Figure 2)8 Not only is urban sprawl problematic with regards to the environment, there is also evidence pertaining to a variety of health problems associated with it as well; some of which include obesity, diabetes, cardiovascular disease, and respiratory disease.12 Urban sprawl in the United States originated in the 1950s with the desire to live outside of city centers to avoid traffic, noise, crime, and other problems. As suburban areas developed, cities expanded in geographic size faster than they grew in population producing large metropolitan areas with low population densities all of which were interconnect by a large number of roads. Residents of these sprawling cities chose to commute to work, school, or other activities by automobile rather than live within the city where each is within walking distance from the another.13 People who live in large metropolitan areas often find it

Figure 2 Urban sprawl as a result of uncontrolled development around the periphery of cities.

difficult to travel even short distances without using an automobile, because of the remoteness of residential areas and inadequate availability of mass transit, walkways, or bike paths.14 There is substantial evidence that urban sprawl has negative effects on human health due to a number of factors. First, an urban development pattern that necessitates automobile use will produce more air pollutants, such as ozone and airborne particulates, than a pattern that includes alternatives to automotive transportation.

The relationship between air pollution and respiratory problems, such as asthma and lung cancer, is well documented. Second, cities built around automobile use also provide fewer opportunities to exercise than cities that make it easy for people to walk or bike to school, work, or other activities.

Exercise has been shown to be crucial to many different aspects of health, such as weight control, cardiovascular function, and stress management.15,16

Preserve Open Spaces By maximizing building area with a minimum physical footprint, tall buildings can support dense arrangements and help in preserving open and natural spaces (Figure 3) by accommodating many more people on a smaller amount of land area, therefore, preserving natural areas in and around cities and localities that provide habitat for plants and animals, recreational spaces, farm and ranch lands, places of natural beauty, critical environmental areas and recreational community spaces.17 The availability of open space provides significant environmental quality and health benefits that include improving air pollution, attenuating noise, controlling wind, providing erosion control, moderating temperatures, and flood prevention, while at the same time protects surface and ground water resources by filtering trash, debris, and chemical pollutants before they enter a water system. In many instances it is less expensive to maintain open space that naturally maintains water quality, reduces runoff, and controls flooding than to use an engineered infrastructure, such as water filtration plants and storm sewers.18 Lands with natural ground cover have no surface runoff problems because 90% of the water infiltrates into the ground and only 10% contributes to runoff.

However, when 65% of the site is covered

5

Figure 3 Artist’s rendering of a city park demonstrating the benefits that coincide with preserving open spaces within a city.

with impervious surfaces, 35% of the precipitation contributes to runoff. On paved parking lots, where the paving surfaces are impermeable and allow for a small amount of infiltration, about 98% of precipitation becomes runoff.19 Improve Environmental Quality Urban sprawl can reduce water quality by increasing the amount of surface runoff, which channels oil and other pollutants into streams and rivers. Poor water quality is associated with a variety of negative health outcomes, including diseases of the

6

gastrointestinal tract, kidney disease, and cancer.20 In addition to air and water pollution, adverse environmental impacts of sprawl include deforestation and disruption of wildlife habitat.Tall buildings can also have a positive impact on the people within the city as well. People living in dense compact developments may have more opportunities for or access to exercise and healthy foods than do people in sprawling areas. When a city (figure 4) provides a much cleaner and healthier environment for its citizens the natural response is to spend more time outdoors.

Population Growth Today, nearly fifty percent of the total world population, about 7.3 billion people, live in an urban setting. This transition will occur at an increasing rate over the next few decades as the suburban populations migrate and become city dwellers.22 By 2030, it is expected that about sixty percent of the world’s population will be urban. As the trend continues, by 2050, over 80% of the world population will live in urban areas when the world’s population is expected to reach 9.7 billion (Figure 5).23 Due to both fertility and mortality rates the human population, since the 18th century, has been growing exponentially. This is primarily due to advances in technology of the industrial revolution.24 The industrial revolution led to development of coal-fired engines, factories, more efficient agriculture and food production, as well as faster transportation between and across continents. The increase in food supplies resulted in more and larger families. The rapid increase in inventions were empowered by the exponential exploitation of coal, gas, and oil which had a positive feedback on the food supply by enabling the production of pesticides, fertilizers, and automated farming devices. In the industrialized world, the development of modern medicine lowered infant mortality rates and increased longevity.25

sumes and wastes} and technology (T) through which we (1) prolong life, (2) produce things more quickly and cheaply (feeds back into consumerism and affluence) and (3) grow food faster – which feeds back into the population. This equation summarizes the impact of humankind on the planet.28

Figure 4 Photograph of downtown Bangkok, Thailand demonstrating the much improved environmental quality of the city.

At the dawn of the Industrial Revolution in the mid 1700s, the world’s human population grew by about 57 percent to 700 million. In only 100 years after the onset of the Industrial Revolution, the world population grew by 100 percent to two billion people in 1927. Before the start of the 21st century the world population grew to six billion people; that calculates to a 400 percent population increase in a single century. Since the 250 years from the beginning of the Industrial Revolution to today, the world human population has increased by six billion people.26

The Human Impact The impact of this population growth on the environment since 1750 has been extensive. In the last 20 years, there has been increasing evident of the human impact on the environment including: droughts, floods, famines, extinctions, and global warming.

This impact has been expressed in what has become known as the Commoner- Ehrlich Equation: I = P x A x T This states that the impact (I) on the environment is directly proportional to the population size (P), the ‘affluence’ (A) {defined as the resources a population con-

7

Figure 5 Graphic illustration showing the global population over the past ten thousand years.

8

A NEED FOR ALTERNATIVE BUILDING MATERIALS

Embodied Energy Buildings not only use energy, it takes energy to make them.This is “embodied” energy, which is all the energy required to extract, manufacture and transport a building’s materials as well as that required to assemble and “finish” it. As buildings become increasingly energy-efficient, the energy required to create them becomes proportionately more significant in relation to that required to run them. Among the materials available for construction, the most common building material with the least embodied energy is wood. Timber is regarded as the

Figure 6 Embodied Energy of Construction Materials in the USA

Figure 7 Transportation related carbon dioxide emissions including empty returns.

greenest building material, however, from the perspective of embodied energy, every building, no matter what its condition, has a large amount of energy locked into it.29 Figure 6 shows a comparison of materials and the amount of embodied energy of each.

Brick is the material with the next lowest amount of embodied energy, followed by concrete, plastic, glass, steel and aluminum.

Also, because the energy used in transporting its materials becomes part of a building’s embodied energy, the transportation of raw materials and final products

also needs to be accounted for as this too generates CO2 emissions.30 Figure 7 shows how the transportation of one kg material over one km distance depends strongly on the method of transportation. The variation in emission figures depends on the size of the transportation vehicle and its energy efficiency. A large concrete transportation truck will emit around 100·10-6/km while a small truck for local transportation purposes will emit at least twice as much. Therefore it is very important to keep transportation of materials to a minumum.31

9

Concrete Concrete has a large carbon footprint and is a highly energy intensive material to produce. As the world’s understanding of climate change evolves, it is becoming more evident of the impact that buildings contribute to the green house gases causing climate change. Concrete production alone represents roughly 5% of world carbon dioxide emissions.32 Cement is manufactured from a combination of naturally occurring minerals (calcium, silicon, aluminum, iron and small amounts of other ingredients) and heated in a large kiln to over 2700° F to convert the raw materials into clinker; Figure 8 illustrates this process. Heating of the kiln to produce the clinker is the largest contributor in the consumption of energy and ultimately the generation of greenhouse gases. The amount of carbon dioxide produced from the calcination process is approximately 0.55 kg CO2 per kg cement clinker. As a comparison, the production and transportation of concrete represents more than 5 times the carbon footprint of the entire airline industry. It is clear that the very fundamentals of what materials we build our buildings with are worth re-evaluating.33 In addition to fossil fuel emission from cement manufacture, the carbon dynamics of concrete materials include the chemical re-

10

actions of carbonation that occurs over the life cycle of the material. Carbonation is a chemical process in which the calcium oxide present in hardened cement products binds with carbon dioxide in the atmosphere to form calcium carbonate; its rate depends on the surface area of the concrete exposed to air. It is also influenced by several other factors, including the exposed uncoated surface area of the concrete, the composition of the cement used to make the concrete, the relative humidity and temperature of the environment and the exposure conditions.34

Figure 8 Conversion of raw materials into clinker produces approximately 0.55kg carbon dioxide per kg of clinker.

Steel As more sustainable buildings continue to be built, steel may be viewed as a poor choice due to its high embodied energy and low thermal performance. The amount of energy used and carbon emissions generated by the steel industry depend on production rates. Increased production rates tend not only to increase input requirements and emissions but are also accompanied by higher capacity and profits.35 Steel is among the largest energy consumers in the construction industry since the manufacture of steel involves many energy intensive processes (see Figure 9) that consume raw or recycled materials, such as iron ore and scrap metal. Raw materials with intrinsic carbon contents are the primary resources for steel production, resulting in a significant impact on the climate. The steel industry is a major consumer of electricity, used to power its lengthy production process; virtually all of the greenhouse gas emissions relates to energy consumption.

Although there are no direct emissions of CO2 associated with the manufacturing process, consumption of electricity produced by coal and gas fired energy sources are standard. Energy consumption for steel production represents about 2.5% of domestic energy use and about 8% of all U.S. manufacturing energy use.35

Figure 9 Manufacturing process for the production of steel.

Wood Concrete and steel have a large carbon footprint and are highly energy intensive materials to produce. Wood is not only made from a naturally renewable source but has been shown to be more sustainable than other materials because it generally requires less energy to produce compared to structural steel and reinforced concrete.

In addition, due to photosynthesis, wood acts as a carbon sink, storing approximately

50% carbon by weight. These sustainable aspects of wood make wood an attractive material from which to construct tall buildings.36 Tall wood buildings are far from being a new concept and have, in fact, existed for centuries. Dating as far back as 600 AD, the Japanese build up to 19 story wood buildings, many of which are still standing today.37 Currently, there exists a new trend in the

building industry and that trend is the recurrence of tall wood buildings. Within the past decade, the design industry has been increasingly looking toward timber as a building material for the construction of tall buildings. This interest is partly due to the development of engineered wood products that not only allow for new construction techniques but provide potential economic benefits as well. The engineered wood products used in the construction of tall buildings falls in the category of mass timber, which is much different than smallscale dimensional lumber. Typical low and mid-rise buildings generally utilize light timber frame construction and are limited in size and open area. Mass timbers, however, are solid panels of wood engineered for strength through laminations of different layers and include four primary products: Cross Laminated Timber (CLT), Laminated Strand Lumber (LSL), Laminated Veneer Lumber (LVL), and Glued Laminated Wood (Glulam).38 These Mass Timber products offer significant benefits over light wood frame techniques in terms of fire, acoustic performance, and structural performance, scale, material stability and construction efficiency. Heavy timber frame construction is composed of a lesser number of large-sec-

11

tion engineered products to form the building superstructure. While this includes solid sawn lumber sections, modern timber buildings generally use engineered timber products. The use of heavy timber frame construction allows for greater design flexibility (relative to light timber frame construction) including longer unsupported spans, open-plan areas, and taller construction. The two predominant forms of heavy timber construction include post and beam construction and panelized construction.38 Wood is typically the best principal material available for building structures with respect to embodied energy and carbon emissions. Manufacturing processes associated with wood products also require less fossil fuel-based energy and are responsible for far less greenhouse gas emissions than the manufacture of concrete or steel.

While this is true, wood construction has its own set of negative environmental attributes that cannot go unnoticed. As previously mentioned, trees act as carbon sinks by absorbing CO2 from the atmosphere and release oxygen for animals to breath.

As humans continue to exhaust more carbon dioxide in the air, the need for trees to remove that carbon dioxide from the air increases. Since building with wood requires the cutting down of trees, this contributes to the global problem of deforestation.39

12

Tall Wood Buildings Mass Timber buildings today are changing what was previously possible to be built in wood around the world. Different systems will continue to evolve and continue to reach record heights never before thought possible. Engineering analysis has shown that in the case of a wood structure it is sometimes wind load on the building that mostly governs the design. This is due to the fact that wood building are significantly lighter in weight than concrete or steel structures.

Figure 10 Stadthaus building located in London, England.

Tall Wood buildings are not a new concept but have existed for centuries. Over 1400 years ago tall pagodas were built in Japan up to 19 stories in wood and still stand today. As the technology has evolved, new innovations have triggered a race for to create taller wood buildings worldwide. In the last five years, 17 tall wood buildings have been built around the world that are over seven stories in height, including the nine story Stadthaus residential building in London, the seven story Tamedia office building located in Zurich, Switzerland, and, Forté, the tallest to date, a residential building in Melbourne, Australia, is ten stories tall. Each building design takes a different structural approach to mass timber construction.

The Stadthaus building (Figure 10) was constructed entirely in timber and was assembled using a unique cross-laminated structural system, pioneered by KLH of Austria. The cross-laminated solid timber panels form a cellular structure of platform framed, timber load bearing walls, including the stairs and timber floor slabs. Each of the panels was prefabricated and arrived on site and craned into position. This construction process drastically reducing the time; the entire nine story structure was assembled within nine weeks.

The project for the headquarters of the

The 10 story structure offers retail at the ground floor and 23 apartments above for city residents. By using Cross Laminated Timber (CLT), Forté, reduces CO2 equivalent emissions by more than 1,400 tons when compared to concrete and steel.

In addition to reduced carbon emissions, Forté combines other sustainable initiatives, such as LED lighting and smart metering. Rainwater tanks collect rainwater from the roof which is then used for the toilet fixture as well as the fire sprinkler system.

Figure 11 Tamedia building located in Zurich, Switzerland.

Swiss media company Tamedia is situated in the heart of the city of Zurich, Switzerland.

The structural wood system is the greatest extent of innovation within the project.

The structural elements are entirely visible giving a special character and high quality spatiality to the working atmosphere. From an architectural point of view, the main feature of the project is the assembly method, which uses no glue or fasteners of any kind.

The wood elements are simply milled to precise dimensions and assemble in such a way that the need for fasteners at the connections has been completely eliminated.

Forté is currently the tallest timber residential building in the world.

Figure 12 Forte building located in Melbourne, Australia.

Deforestation A growing forest removes carbon dioxide from the atmosphere and stores this carbon in vegetation and soil. Deforestation is a critical contributor to anthropogenic climate change and many more negative environmental effects. Due to the loss of these ecosystems extinctions of countless plants, animals, and insects are happening at an alarming rate. Massive extinctions have occurred five times during the earth’s history, the last one was the extinction of the dinosaurs, 65 million years ago. Scientists are calling what is occurring now, the sixth mass extinction. Rainforests cover less than 2% of the Earth’s total surface area, yet they are home to 50% of the Earth’s plants and animals. Deforestation causes the loss of over 137 animal and insect species per day; totally to more than 50,000 species per year. It is estimated that at least 80% of the developed world’s food originated in the tropical rainforest. At one time there were more than 3000 species of fruits found in the rainforests; of these, only 200 are now in use in the Western World. Tropical forests have given us chemicals to treat or cure many ailments from inflammation to diabetes or even cancer or AIDS. The U.S. National Cancer Institute has identified more than 3500 plants that are active against cancer cells; 70% of these plants are found in

13

Figure 13 Satellite images showing deforestation within the Amazon rainforest over a ten year period

the rainforest. Twenty-five percent of the active ingredients in today’s cancer-fighting drugs come from organisms found only in the rainforest. With this in mind, deforestation is causing an extinction rate of about 50 species per given day. Sadly, less than one percent of the tropical rainforest species have actually been analyzed for their medicinal value.40 The United Nations estimates that over 100,000 acres of rainforests are destroyed each day. Figure 10 shows the result of deforestation within the Amazon rainforest over a ten year period; each photo taken

14

approximately five years apart. In some tropical countries emissions from deforestation can be as high as 50 to 70 percent; higher than from all other sources combined. The world has already lost 50% or 75 million acres of its temperate rainforest; mostly in just the last 40 years. They are also one of the world’s primary carbon reservoirs. By absorbing carbon dioxide from the air, storing the carbon and giving us oxygen, tropical forests act as the world’s thermostat, regulating temperatures and weather patterns.41

Global Warming Global warming, sometimes referred to as climate change, is the increase in the average temperature of the Earth’s atmosphere and oceans as a result of the buildup of greenhouse gases in our atmosphere.

Greenhouse gases, carbon dioxide, can either be released by natural events such as volcanic eruptions or from human activity such as deforestation or the burning of fossil fuels.42

Global warming is a serious threat that scientists believe is the cause of sea level rise, extreme weather, changes in agricultural yields, glacier retreat, species extinctions and increases in disease. These issues are significant for living conditions since they will profoundly impact urban environments on a global scale. Consequently, fighting global warming and reducing carbon dioxide emissions are becoming prime goals of many cities.

The building industry represents approximately a third of green house gas emissions worldwide.This is due to the embodied energy consumption in materials and building construction and maintenance as well as fossil fuel consumption in building operations such as heating, cooling, and lighting.

Urban environments around the world will continue to demand large building solutions, as urban density becomes an increasingly important part of addressing climate change. This is especially important knowing that the United Nations estimates 3 billion people will need a affordable housing in the next 20 years.43 Figure 11 shows atmospheric concentrations of carbon dioxide over the past 400,000 years as expressed in units of parts per million by volume (ppm). Since the beginning of the Industrial Revolution, in the late 1700s, the concentration of carbon dioxide in the atmosphere has increased by about 100 ppm (from 280 ppm to 380 ppm). The first 50 ppm increase took place in about 200 years, from the start of the Industrial Revolution to around 1973; the next 50 ppm increase took place in about 33 years.44

Figure 14 Atmospheric concentrations of carbon dioxide over the past 400,000 years as expressed in units of parts per million by volume (ppm).

15

16

TIME FOR CHANGE

What are Bamboo Fiber Reinforced Composites?

Anatomical properties of bamboo fiber constitute bamboo as a superior renewable source when compared to all other known natural ligno-cellulosic fibers. Fibers from the bamboo plant are separated and sized in the form of individual fibers or strips.

These fibers or strips are then informally imbedded within a polymer matrix (epoxy, unsaturated polyester resins or similar).

Processes have been developed through trials and research in order to cast bamboo fiber reinforced composites (BFRC) uni-directionally, bi-directionally and multi-directionally via compression molding, extrusion, or pultrusion methods. The resulting material combines the strength and resilience of bamboo fiber with dimensional stability and moisture resistance of thermosetting resins.

A Brief History of Bamboo Bamboo was first found and used in China more than 5000 years ago and today it is being utilized not only for its exceptional strength but also for its cosmetic appeal.

Bamboo’s tensile strength was once essential in the development of bridges; however, today we can find a bamboo alternative in almost every industry. In today’s environmentally conscious society, we have finally begun to utilize bamboo in everything from kitchen wear to clothing. Even so, with all of today’s technological advances, the world is still without a product that utilizes the full potential and harnesses the robustness of this amazing plant. A very unique characteristic that bamboo possesses is that it is strong in both tension and compression.

While tensile strength remains the same throughout the age of the bamboo plant, compressive strength increases, as it gets older. Of the 1600 known species of bamboo, most reach maturity in three years; others are known to double in size in a single day. The advantages of bamboo fibers reside in its high stiffness, high strength, low weight, low cost, biodegradability, non-abrasive nature and sound absorption.

Different species of bamboo, members of the grass family, are native to diverse climates around the world—from sub-Saharan Africa to northern Australia and from

southeastern North America through much of South America. Bamboo also grows profusely throughout most of Asia. Bamboo is especially notable for its strength, hardness, and rapid rate of growth. Bamboo has greater compressive strength than concrete and a tensile strength comparable to that of steel.

Bamboo grows much faster than trees, with some species growing up to four feet per day.45 Nearly all of the bamboo used in North America is grown in China, with small amounts coming from Vietnam and some poles for structural uses coming from South America. Moso bamboo (Phyllostachys pubescens) is known as mao zhu in China; is the most widely cultivated species in China, with some plantations dating back hundreds of years. One fourth of the world’s population relies on bamboo for many of the objects used in daily life. While this robust plant has been primarily used as scaffolding in the construction industry; bamboo is being used today for a wide variety of purposes unrelated to building construction. Bamboo cutting boards are increas-

17

ingly popular, and other bamboo products age and long-term durability are some of including fabrics for clothing, paper, fencing, the drawbacks of using natural bamboo in and of course chopsticks.46 structural concrete, which result in its segregation from concrete matrix.48 Bamboo as a Building Material Developing countries have the highest deUnlike wood, bamboo grows nearly straight mand for steel reinforced concrete, but its entire length and without any knots or often do not have the means to produce major branches. As a result, bamboo has the steel to meet that demand. Bamboo been shown to have higher tensile strength has been used in these regions as reinforcethan steel, higher compressive strength ment, though dispute exists over its effecthan that of concrete, and higher strength- tiveness in the various studies done on the to-weight ratio than steel. Additionally, and subject. While bamboo has the necessary unlike wood, bamboo contains a high sili- strength to fulďŹ ll this function, it is importca content and cannot be digested by ter- ant to ensure that the bamboo does not mites.47 The other advantage bamboo has absorb water, swell, and crack the concrete. over other construction materials is that it is a rapidly renewable sustainable resource. Due to its fast growth rate bamboo absorbs three to four times more carbon dioxide than an average tree, which means, over time, bamboo forests have to potential to absorb the excess carbon dioxide from the atmosphere.

Bamboo Fiber-Reinforced Concrete Given its outstanding tensile properties, replacing steel reinforcement in reinforced structural concrete with bamboo is of high interest. However, the natural form of bamboo poses many problems when it is used as reinforcement in concrete. Shrink-

18

The bamboo must endure several procedures to overcome this shortcoming.49 A solution composed of borax and boric acid is commonly used to accomplish this.

Another option is to boil the bamboo that is to be used for construction after it has been cut, as this will remove the starches found in the plant that attract insects.

Bamboo Strength In trials of tensile strength, bamboo outperforms most other materials, reinforcement steel included. The strength and lightweight nature of the plant is due to its hollow, tubular structure, evolved over millennia to

Figure 15 Material comparison of Bamboo Fiber Reinforced Composites with other construction materials.

resist wind forces in its natural habitat. Due to its incredibly rapid growth cycle and the variety of areas in which it is able to grow, bamboo is also an inexpensive resource. With such rapid growth, bamboo plants absorb large quantities of CO2, three to four times more than most trees, meaning that its cultivation as a building material would help reduce the rate of climate change.50 Figure 15 shows a comparison of bamboo with other construction materials.

Global Distribution of Bamboo The bamboo is a grass grown in various continents of the world including Asia, Africa, and the Americas. The main areas of distribution are the tropics, in particular, South East Asia. Bamboo grows best at sea level but can be found at altitudes of up to 3800 m. Most bamboo species grow on sandy loam to loamy clay soils at temperatures from 28°C to +50°C. Like other grasses, they have tubular blades, lancet shaped cover leaves and panicular flowers.

The growth pattern of the trunk is similar to that of the palm tree; emerging with its definitive circumference from the soil without increasing in diameter later.51

Chemical Composition and Structure The chemical composition of bamboo fiber consists of roughly 90% cellulose, hemicelluloses and lignin. The remaining 10% are protein, fat, pectin, tannins, pigments and ash. The chemical composition of the bamboo fiber is shown in Figure 12. It is quite common for the chemical composition of bamboo to changes with age; in particular it is the cellulose content that decreases as the age of the plant increases. The stiffness of the bamboo comes from the lignin, which also gives the plant its yellow color. The unidirectional arrangement of bamboo fibers within the plant tissues and cell walls is one of many unique properties of bamboo.52 Bamboo fibers possess both broad and narrow polylamellate and lamella structures as compared to the sandwich

Figure 16 Chemical composition of a mature bamboo plant.

like structures of wood.53 Another unique characteristic that bamboo possess at the cellular level is the hemicellulose, phenolic acids covalent bonding in cell wall structure. The variation of different components across the cell wall enhances its various mechanical-physical properties.54 Material Research Future sustainability, population increase, global warming, over harvesting of natural reservoirs and other threats to environment have scientists and engineers focusing on the use of natural, renewable materials for the development and fabrication of polymer composites.55 Synthetic fibers have been used as reinforcement for many years within the composites industry; however natural fibers offer many benefits and are therefore gaining much momentum as a synthetic fiber substitute in various applications. The combination of natural fibers with polymer matrices can produce products that are competitive with synthetic composites in terms of weight, strength and cost.56 Bamboo is one of many agricultural crops that can be exploited for the design and development of polymer composites due to its high strength and low weight. In trials of tensile strength, bamboo outperforms most other materials, steel included, due to the

19

longitudinal alignment of fibers. It achieves this strength through its hollow, tubular structure while its lightweight structure also makes it easy to harvest and transport. Due to its incredibly rapid growth cycle and the variety of areas in which it is able to grow, bamboo is an inexpensive resource. Such rapid plant growth requires the absorption of large quantities of CO2, meaning that its cultivation as a building material would help reduce the rate of climate change.57 For the purpose of this research project, numerous articles were referenced relating to the study and physical testing of bamboo fiber reinforced composites. In one comparison study bamboo was compared with other natural fibers as a reinforcement material in a polyester matrix in order to yield better properties. The results showed that the bamboo fiber composite yielded better properties both in terms of strength and resistance to various chemicals.58 Tensile and flexural strength have been extensively studied and the results indicate that chemical treatment of the bamboo proved to enhance the material. Alkali treatment ensures less water uptake by the composites making them more durable. In another recently published research project, various chemicals were used to modify the bamboo fiber to estimate vari-

20

ous mechanical, physical and morphological properties of bamboo reinforced polyester composites.52 They concluded from the obtained results different variation in mechanical, physical and morphological properties of bamboo reinforced polyester composites.

Researchers investigated the effect of mercerization of bamboo fiber on physical, mechanical and thermal behavior (weathering behavior, % water uptake, % thickness swelling, and thermal stability) of bamboo fibers reinforced novolac resin composites.52 The effect of mercerization of both treated and untreated on properties of composites were evaluated. Earlier reports clarified that these modification improve various

properties such as wetting ability, interfacial strength, mechanical properties, weathering and thermal properties of the composites.

The weathering behavior, water absorption, humidity and UV exposure along with dimensional changes of fabricated composites were carried out for different duration and atmospheric conditions. They reported that better thermal properties were observed after alkali treatment due to better interfacial interaction between alkali treated bamboo fibers and novolac resin.

Thermal degradation studies revealed that alkali treatment of the fiber imparts better thermal stability to the composites as compared to untreated. The thermal stability was enhanced by using a more con-

Figure 17 The effect of different derivatives of silanes in addition to alkali treatment on water absorption properties of bamboo epoxy composites

centrated solution and the best properties were observed at 20% alkali treatment.The flexural and Young’s modulus was also calculated theoretically and the results were obtained for fiber/matrix adhesion and fiber alignment. Figure 13 shows the effect of different derivatives of silanes in addition to alkali treatment on water absorption properties of bamboo epoxy composites were extensively carried out.52 Both alkali as well as silane treatment resulted in a reduction of water absorption.

The overall performance of the composite depends on various physico-mechanical properties particularly void content. It reported a short bamboo fiber reinforced epoxy composites and their density, void content, and percent weight reduction from the matrices. The void content directly depends on the fiber content used, and it was observed that void content continued to decrease with increasing fiber content. A similar trend was observed with the density of these composites as well. A linear relationship was found for weight reduction with respect to fiber content and material weight.52

using epoxy resin as the primary bonding agent.59 It reported that wear performance of bamboo fiber reinforced epoxy resin composites have excellent wear resistance.

The friction performance showed enhanced by almost 44% at low sliding velocity for anti parallel orientation as compared to the higher sliding velocity. Morphology of these composites exhibited superior orientation in antiparallel direction as compared to other directions.52 This observation was attributed to high shear resistance incurred by the bamboo fiber that influenced the wear and friction for the different sliding velocities. The mechanical properties such as tensile strength, elastic modulus, flexural strength and flexural modulus were evaluated and it was observed that silane treatment improved the tensile and flexural strength. When mechanical properties of the bamboo husker were studied, fibers modified with coupling agents showed better results than untreated fibers.52 During the research a mechanical extraction process was developed to obtain long bamboo fibers that could then be used to epoxy reinforced structural composites.

Flexural strength and Young’s modulus were Epoxy Based Bamboo Fiber-Rein- theoretically calculated and showed good forced Composites results. These tests were completed in orFor this testing, the adhesive wear and fric- der to obtain the estimated fiber adhesion tional performance of bamboo fiber rein- and alignment within the composite matrix. forced epoxy composites were also studied Water absorption properties tested and

observed based on different derivatives of silanes used. The results showed improved fiber-matrix bonding when water reduction was achieved. The main cause of less water absorption is due to a greater hydrophobicity. Many different silanes were used during this study to determine the best saline-epoxy interaction; however, the best results were observed from the amino functional silanes.60 Void Content The overall performance of the composite matrix depends on various physical-mechanical properties, but most importantly void content. The void content refers to the number of areas within the composite where fibers and matrix are not in direct contact with one another. In this report, short bamboo fibers were used and their density, void content, and percent weight reduction from the matrices were observed. The void content is directly dependent on the fiber content used; as void content decreases with increasing fiber content. A similar trend was observed with density as well. A linear relationship was observed for weight reduction for these composites as a function of the matrix; as fiber content increased, the composites weight decreased.61

21

Polypropylene Based Bamboo Fiber-Reinforced Composites Polypropylene (PP) composites possess considerably high flexural properties, which makes them suitable to replace many of the glass fiber composites used in various industries. Composite of polypropylene and bamboo fiber have been studied for their degree and rate of biodegradation properties.52 Degradation of the bamboo fiber PP composites were observed and the discovery was that degradation had taken place in the areas where fibers remained attached to the matrix in terms of physical forces.

SEM results revealed that bamboo fibers were damaged if exposed while fibers embedded deep in the matrix are almost unaffected. It was concluded that bamboo fiber can be used as a reinforcing agent in synthetic polymers, reducing the polymer content used in manufacturing, therefore reducing the generation non-biodegradable waste.

Another study was conducted using recycled polypropylene treated with maleic anhydride in order to improve adhesion between fiber and matrix. The direct effects of different percentages and modifications of bamboo fiber on various physical and mechanical properties of PP composites indicated that both play an important role in varying these properties. The effect of alkaline and acetylating agents on mor-

22

Figure 18 Mechanical properties of bamboo fiber based reinforced composites.

phology of bamboo fiber was also studied.

The comparison of alkaline and acetylating treatment showed that mechanical properties were improved and the adhesion between bamboo fibers and polypropylene matrix was enhanced. This study also demonstrated that PP proved to be the superior polymer for the bamboo fiber matrix yielding better mechanical properties.

The increased mechanical properties of composites were reported as compared to conventional composites. The studies depicted the decrease in void content due to stronger impregnation of the resin within the matrix and showed a tremendous increase in tensile strength and modulus.62 Strength comparisions of various composite formulations are shown in Figure 14.

Timber Tower Case Study This case study was done on the Dewitt Chestnut building, which was constructed in Chicago, Illinois in 1966. The 42 story residential tower was designed by SOM and stands 396 feet tall. The floor plan dimensions are 80’-0” by 124’-6” with reinforced concrete flat plate floors and framed tube columns spaced 5’-6” on center.

This building was chosen for this case study for the following reasons: It is a real building, which has been successful and is still

marketable, the lease depths of the floors are consistent with contemporary residential fit-outs, the rectilinear building geometry is a relatively simple shape, it is very efficient with structural materials, the data was easily accessible.

Design Approach The design approach is to replace specific structural elements of the original concrete framed tube structural system with mass timber components

Dewitt Chestnut Apartments Location: Chicago, Illinois Construction Time: 1963-1966 Building Height: 396’ Architect: Faziur Rahman Khan Occupancy Type: Residential Structure: Reinforced Concrete Number of Floors: 42 Figure 19 Section cut showing the new design approach using mass timber to replace specific reinforced concrete elements.

23

Figure 20 Typical wall joint detail and shear wall locations shown in red.

Figure 21 Typical spandrel detail and floor slabs shown in red.

24

(see Figure 15). The goal was to develop a structural system for tall buildings that uses mass timber as the main structural material and minimizes the embodied carbon footprint of the building. The advantage of using mass timber over heavy timber is that the material can scale to larger sizes necessary to support the required loads. The system was designed to utilize the reinforced concrete at highly stressed locations with mass timber being used in the vertical elements such as columns and shear walls. Based on a technical standpoint, SOM believes that this proposed system is feasible; however, additional research and testing is necessary to verify the performance before the building can be realized.63 Structural System The system was designed around two major design criteria for tall buildings. The first is to deal with the lateral loads, which will be done with a reinforced concrete tie-beam that runs around the perimeter of each floor and creating a web through the core of the structure; see figure 17.

This system is designed to deal with both wind and seismic forces and is linked with the mass timber shear walls located at the core of the structure.These shear walls are required to be 12” thick with mass timber (10” thick with the composite) in order to

Figure 22 Typical column joint section detail and column locations shown in red.

handle both lateral and gravitational forces; see Figure 16.

The second design criteria is to handle the gravity loads. In this case 24”x24” mass timber columns will run the parameter of each floor, 18 in total, and act in a way to resist only the gravity loads. When the composite is used to replace the mass timber, the column sized can be reduced to 18”x18”. A column joint section detail as well as column locations are shown in Figure 18. The floor-tofloor height for this timber tower is 9’-0” with 8” thick mass timber floor slabs. The composite will allow the floor slab thickness to be reduced to 6” resulting in a floor-to-floor height reduction of 2” and the overall building height to be reduced by roughly seven feet. The approximate dimensions for each floor slap element are 28’-6”x9’-0”x6”. A spandrel detail showing the slab connection to the beam is shown in Figure 19.

It should also be mentioned that the foundation, basement and first floor plaza will use exclusively reinforced concrete. This is due to the unique nature of the material, which offers superior performance for these areas of construction. The mass timber will be used beginning at floor two to the top of the structure, 41 floors in total.63

Figure 23 Typical spandrel detail and floor slabs shown in red.

25

Member Size Calculations

26

Member Size Calculations continued

Codes and Reference Documents Used:

2012 International Building Code (IBC) 2012 National Design SpeciďŹ cations (NDS) for Wood Construction - ASD/LRFD 2012 Special Design Provisions for Wind and Seismic (SDPWS) ASCE-7 - Minimum Design Loads for buildings and non-buildings structures

27

Sustainable Performance Calculations

Figure 24 Comparison of CO2 emissions, volume of material required, and building weight based on the materials used for the structure.

28

Member Size Calculations the durability of the building, and increased The following pages show the calculations openness and improved entry conditions of that were made to determing the member the lobby levels.63 sizes for each of the composite elements.

Column Spacing Construction Sequencing The location of columns along the perimThe proposed structural system is designed eter of the building is set at approximately to be built in much the same way as that of 24 feet on center, which dictate the dea structural steel building. Mass timber is mising wall layout for the interior design. used for the primary structural elements This column spacing requires the spandrel such as the floors, columns, and shear walls beams to be robust in order to support and are connected using structural steel the floor load, therefore a concrete spanend fittings allowing for the erection of the drel beam was chosen due to the limited timber elements to proceed up the build- strength of timber beams.63 However, based ing without immediate concreting of the on the strength data collected, BFRC show joints. When timber is used, it will account to be of sufficient strength to replace the for approximately 70% of the proposed concrete spandrel beam component resultstructure, while only 30% will be reinforced ing in a further reduction of building weight concrete.63 When BFRC are used, the only as well as CO2 emission. concrete needed is that of the foundation.

Floor-to-Floor Height Foundation and Substructure The floor-to-floor height of the original The foundation of the Dewitt-Chestnut Dewitt-Chestnut building is 8’-9”.The floor building consists of belled caissons bear- slabs are 8” which allows for an approxing on hardpan approximately 75ft below imate floor to ceiling height of 8’-1” for grade. Since both the timber-framed or the living area but in the kitchen and bathcomposite building are much lighter than room a drop ceiling is installed to allow for the original, only 65% of the foundation is building system routing leaving a 7’-1” ceilneeded. From the basement to the second ing height in these areas. The goal for the floor, the building base will be constructed timber project was to match these heights entirely of reinforced concrete. Concrete but for this to happen the floor-to-floor framing was chosen for these levels for height needed to be increased by 3”. This added strength for building loads, enhance was due to the increase in member sizes as

compared to the original concrete structure. The result is a floor-to-floor height of 9’-0”.63 This height was reduced to 8’-10” when BFRC were used since the floor slabs could be reduced to 6”. The result is a further reduction for the amount of material required for the structure and would further reduced the weight of the building. A comparison of the building weight is shown in Figure 20. In addition, this will decrease facade surface area and decrease wind forces on the structure.

Floor Framing Strategy Within the Core The inner core framing is constructed with solid timber panels supported on laminated timber beams. From an engineering standpoint, the core can be designed as simply supported mass timber floors and beams with lease span panels on the opposite sides of the link beams. This would guarantee that link beams do not receive any additional stresses such as torsion due to gravity loads.63 Replacing the timber elements in this area is feasible and would again have reduced member sizes.

Sustainability and Carbon Footprint The carbon emissions associated with the construction of the building are referred to

29

as “embodied energy”. The carbon emissions of a building are associated with both the construction as well as the total energy consumed during its lifespan.64 The total carbon footprint of the building is the sum of the operational carbon emissions and embodied carbon emissions; however, the structure of a building is the largest contributor to embodied carbon of the building due to the production of materials used in the structure.

The embodied carbon of a building structure can be reduced in two ways. First, the engineer can try to design a building, which minimizes structural materials. Reducing the amount of structural materials generally reduces cost to the owner and thus a quality structural design already minimizes the materials used. Secondly, the engineer can design a building, which uses less carbon intensive materials.64 A comparison of CO2 emission based on the materials used for the structure is shown in Figure 20.

Fire Protection Techniques Fire resistance is the ability of a structural element or system to withstand exposure to fire such that load-bearing capacity, integrity and insulation are maintained for a specified period of time. Traditionally, the fire resistance of a structure is demonstrated via standardized fire testing where single

30

elements of structure are exposed to an infinitely increasing standard fire curve and assessed against prescribed temperature and integrity limits.While this approach has historically satisfied life-safety objectives, it is unclear whether these same measures will remain unchanged as new technologies, new construction materials and construction techniques become the standard.65 Structural Considerations Related to Fire The fire-resistance ratings for mass timber structural members can be calculated, based on minimum thicknesses and the available thickness after charring (see Figure 21). This fire safety approach is of high

Figure 25 Fire-resistance of members can be calculated, based on minimum thicknesses and the available thickness after charring.

interest and under high levels of testing and analysis. For buildings to be constructed any higher than 10 stories, it would require a comprehensive Building Code Analysis in order to define and document the design approach from a building code perspective.

This would require and utilize fire-engineering techniques supported by international fire research and may encounter more stringent levels depending on the country and the current building codes and regulations. Much more fire testing needs to happen in order to prove the safety of these Mass Timber assemblies. This will assist in growing the confidence level of authorities to use them in larger and higher buildings.66 Based on the research of BFRC, it is believed to have similar characteristics as to those of mass timber when relating to fire resistance and charring.

Increase Member Size Mass timbers are good from a fire performance perspective since the mass wood elements can provide the necessary fire resistance to support the imposed loads on the structure both during and after a fire. Fire risk can be reduced further by the application of gypsum board protection and with the installation of automatic sprinklers. Although timber is considered a combustible material, heavy timber is capable of having

enhanced fire resistance performance due to the mass of wood. When ignited, mass timber forms a char layer that helps retard heat penetration and further pyrolysis.

Based on this fact, heavy timber structural members can be designed to have a sacrificial layer of wood that would act as a fire protective layer. Using tested charring rates, the thickness of this layer can be determined and an appropriate fire-resistance rating and be acquired which will protect the structure from collapse during a fire.

This fire resistance can be incorporated as part of the building structural fire strategy.67 Charring Charring is a process in which the outer layer of wood reaches its ignition temperature, ignites and burns resulting in the creation of a char layer, which has naturally low conductivity. This char layer, along with another newly formed layer known as the pyrolysis zone, insulates the inner core thereby limiting loss of structural integrity of the mass timber elements (Figure 22). Charring rates depend on numerous factors such as timber type, its density, tree species, adhesives used, moisture content as well as the characters of the fire itself.68 In light wood frame construction, the structural components are typically com-

posed of dimensional lumber such as 2x4’s and 2x6’s. These small member sizes make them extremely susceptible to fire and rapid structural failure. It is for this reason that light wood construction is typically protected with a fire resistant membrane such as gypsum board.

Mass Timber construction is good from a fire performance perspective due to their ability to char on the exterior, which results in a naturally insulating and protecting “skin” which protects the inner timber thus retaining its strength. Since the mass wood elements char in a predictable manner; fundamentally they do not have to rely on additional membrane protection.69

Figure 26 Char layer insulates the inner core thereby limiting loss of structural integrity of the mass timber elements.

Charring Rate The charring rate is the rate at which a wood member will burn away when exposed to fire over time. This charring rate depends on numerous factors such as timber type, its density, tree species, adhesives, moisture content and structural forces acting upon it, as well as the characters of the fire itself.70 When considering charring rates for a potential fire it is only being considered for a “worst-case” scenario.

Under most fire conditions, an automatic sprinkler system would operate to control fire development and reduce temperatures.

In the event that the sprinkler system malfunctions, the Mass Timber systems will need to meet certain structural fire protection criteria.

In many urban areas fire strategies, research, and fire engineering methodologies are being used along with performance-based design resulting in many more tall timber buildings being built around the world. The best opportunity to develop a tall timber building in the United States may initially be to work with forward thinking code officials who are comfortable with performance based design that focuses on meeting the “intent” of the code rather than the prescriptive requirements.

31

during a fire.71 The current quality control testing of adhesion/cohesion and density, while helpful, does not solve the problem of assuring that the fireproofing will be present at the time of a fire and function throughout the duration of the fire exposure.

Figure 27 The insulation method consists of spray-applied materials or board materials to the structure to be protected.

Insulation Method The insulation method consists of attaching insulating spray-applied materials or board materials to the structure to be protected.

A variety of insulating materials have been used following this method of protection, including mineral-fiber or cementitious spray-applied materials, gypsum wallboard, asbestos, intumescent coatings, Portland cement concrete, Portland cement plaster, ceramic tiles, and masonry materials. The insulation may be sprayed directly onto the member being protected, such as the columns, beams, or joists and should form both an even thickness and coverage but also adhere well to the structural system (Figure 23). An uneven application, adherence failure, or mechanically damaged areas will result in an overall poor performance

32

Connections Fire performance data for steel connections generally consists of bolts, nails, screws, other fasteners and plate connections. Embedded connections such as screws, nails and bolts tend to perform better than fasteners and plate connections. This is due to the amount of steel area that is exposed to high temperatures, as steel strength decreases with increase in temperature.

Therefore, plates and fasteners fail more

Figure 28 Embedded steel plates are protected by the timber layer, which reduces the exposed area of steel to high temperatures.

rapidly than nails, plates and bolts, which are generally embedded in and protected by the structural timber elements. Unexposed steel plates, also called slotted plates, are a hybrid combining both embedded and plate connections, also called slotted plates, and display significantly better fire resistance than exposed plate connections.

Embedding the steel plates are protected by the timber layer, which reduces the exposed area of steel to high temperatures.

Because of this, slotted plate connections are most often used in mass timber construction.72 Fire Sprinklers Sprinkler systems can be very effective in protecting all structures from the effects of fire. In most cases an automatic sprinkler

Figure 29 In most cases automatic sprinkler systems operate to reduce temperatures and prevent fire development.

system would operate to reduce temperatures and prevent fire development. The result is that minimal structural damage or charring of the wood panel materials will occur. However, in the event of sprinkler malfunction, the structural system will need to meet the 2-hour fire test exposure standard. In a worst case scenario, if the sprinkler system does fail, and the sacrificial layer of wood is burned away, the remaining wood will need to be sufficient to support the imposed loads of the floor assembly above.70

Figure 30 DuPont offer the most advanced heat resistance polymers in the industry and can withstand highs of 220º Celsius.

Fire Resistant Polymers Polymers, like most other organic compounds, will burn readily when ignited on fire. Due to their flammability, applications are limited in enclosed or confined areas such as tall buildings, ships, and aircraft. Polymers offer many advantages over other structural materials like concrete or steel; however, since the risk of fire is much greater, the use in these applications is greatly limited.73 The most logical way to prevent polymer combustion is to design the polymers to have inherently high thermal stability, flame spread resistance, and low burning rate. DuPont offers one of the industry’s broadest and most advanced arrays of heat resistant polymers (Figure 26). Flame-retardant ad-

ditives are a less expensive alternative that affectively impedes combustion and may be the easiest way of making a polymer less flammable. In general, there are two types of additives: reactive and additive flame-retardants. Reactive flame-retardants consist of compounds containing heteroatoms, which will chemically decrease the flammability of the polymer molecules. Alternatively, the additive flame retardant can be physically mixed with existing polymers and do not react chemically with the polymers. Although additive flame-retardants are widely used, limitations exist including poor compatibility, high volatility, and damage to polymer properties.74

Figure 31 Worldwide distribution of bamboos.

33

The Ideal Site Geographic Distribution of Bamboo in the World Bamboo is one of the fastest growing plants in the world and can be grown in most climates, from cold mountains to hot tropical regions. Some species are able to grow as fast as three feet a day; however, the growth rate depends on many variables including local soil and climatic conditions. Figure 27 shows the regions of the world where bamboo species are most commonly grown and cultivated. Many tropical bamboo species die at or near freezing temperatures, while some of the hardier temperate bamboos can survive temperatures as low as −20 °F. 75 Asia, a region of warmer climates during the late Cretaceous period, possesses the largest of all bamboo species, some of which can grow over 100 feet tall with a diameter of over eight inches. The size range for mature bamboo is species-dependent; though most species grow to an average height of 30 feet, the smallest reach only several inches high. Unlike trees, individual bamboo culms emerge from the ground at their full diameter and grow to their full height in a single growing season of three to four months. During this time, each new shoot grows vertically into a culm with no branching out until the majority of the mature height is reached. When branches do

34

They also store carbon, conserve biodiversity, prevent soil erosion, naturally filter water, and moderate Earth’s temperature.

While international efforts to maintain forest benefits have largely focused on preThe Bonn Challenge venting deforestation, a relatively new efForests provide hundreds of millions of fort is underway to restore deforested and people with food, fuel, fiber, and livelihoods. degraded lands around the world.

grow, they extend from the nodes near the top of the plant. Within the next few years, the pulpy wall of each culm hardens giving the plant its characteristic strength.76

Figure 32 The Bonn Challenge is an international movement to restore 370 million acres of degraded and deforested land by 2020.

proximately 1 gigatonne of carbon dioxide can be sequestered per year. This number increases to 3-4 gigatonnes if bamboo were used in place of trees. Many species of bamboo sequester much more carbon dioxide than an average tree due to the rate at which it grows. It may be possible then to grow vast forests of bamboo around the world and begin sequestering the excess carbon dioxide from the atmosphere, which may slow, stop or reverse global warming.77

Figure 33 Projected residential needs for the state of Florida over the next 25 years.

This global target was unprecedented in ambition and scope; yet so far, over 20 countries have responded to the challenge, expressing an ambition to restore more than 148 million acres by 2020. The Global Partnership on Forest Landscape Restoration (GPFLR) has mapped ďŹ ve billion acres of deforested and degraded land across the globe with potential for resto-

ration (see Figure 28).

With atmospheric carbon dioxide levels higher than they have ever been in human recorded history, it is obvious that human activity is having a negative effect on the planet leading to global warming. The question now is if whether or not these effects can be reversed or slowed. By restoring 370 million acres of forest landscapes, ap-

Sustainable Developments Needed in Florida Figure 29 shows the projected residential needs for the state of Florida over the next 25 years; resulting in a loss of 3,000,000 acres of aquifer recharge lands unless drastic changes are made in the way these developments take place. The State of Florida, like all other states, needs sustainable developments due to both population and limited resources. Florida’s population is predicted to see a 72 percent growth in this time; reaching nearly 27.5 million. Urban developments, suburban sprawl, transport pressures, coastal densities, habitat destruction, and reduced rural lands will be the inevitable result of this population increase unless expansion takes place responsibly.78

35

• • •

Florida Sustainable Communities Demonstration Project The Florida Sustainable Communities Demonstration Project was created by the Florida Legislature in 1996 to promote community involvement in achieving higher levels of energy efficiency and environmental protection throughout Florida. The Demonstration Project was developed as a way to evaluate which initiatives are most effective for producing sustainable communities.

Twenty-eight communities applied for the designation as a “Sustainable Community” under the project, from which five communities were selected (Orlando being one of them).79 Each community is introducing a variety of initiatives designed to meet six goals: • Restore key ecosystems • Create quality communities and jobs • Achieve a cleaner, healthier environment

36

Limit urban sprawl green jobs, and transform developing arProtect wildlife and natural areas eas into walkable communities. With sucAdvance the efficient use of land and cess, the city hopes to foster sustainability other resources. throughout the entire community, including residents, businesses and institutions.

Green Works Orlando Commitment to sustainability in specific Through the implimentation of the Green areas will enhance quality of life within the Works Orlando program the city is at- city and generate economic growth for the tempting to become one of the greenest Orlando area. The Green Works Commucities in America. Beginning in 2007, Orlan- nity Action Plan was launched by Mayor do continues to create efficiencies in gov- Buddy Dyer to show his commitment to ernment operations resulting in a reduction turn Orlando into the green city capital of in costs, energy consumption, and carbon the United States.80 emissions. The city is also making great efforts to improve transit options, create

Figure 34 Greenworks Orlando neightborhood proposals.

CONCLUSION

In recent years the utilization of bamboo has been strengthened to exploit bamboo as non-wood renewable fiber. Within the past decade both theoretical and applied research has lead to an evolution in on bamboo-based products. These composites have replaced traditional wood in both indoor and outdoor applications.

More recently, bamboo products are being developed that utilize the natural strength the material offers, which allows for much improvements over traditional products including dimensional stability, longevity, weather resistance and impact resistant.

The global population will continue to rise for the foreseeable future, however, a sustainable tomorrow for future generations lies in the decisions that are made today.

High performance, biodegradable materials from renewable plant sources can form new platforms for sustainable technologies such as BFRC.To design such composites, a thorough investigation of the fundamental, mechanical, and physical properties of bamboo fibers composites is necessary.The attempt for this project was to obtain information for basic properties of bamboo fiber based

composites and use the available strength values to predict the material performance when used in structural applications for tall building construction. Scientists worldwide have conducted a wide range of studies and continue to research bamboo fiber based composite to gain a better understanding of chemical modification, mechano-physical, thermal and other properties.

Additionally, building design value can be increased with the use of a material that is simultaneously cost effective and reduces the environmental impact during construction.

While much research continues to be done, there are still barriers obstructing the realization of a structural system comprised of bamboo composites. Before this building revolution can begin many things will need to happen including additional testing in material strength and longevity, as wells as fire resistance engineering. However, results of this research suggest that construction of tall buildings using BFRC is not only technically feasible but may be superior to all other construction materials available today. There are numerous timber tower

projects being built in many areas of the world, which is evidence that construction technologies are already adapting to a changing world. As carbon dioxide levels continue to rise, escalating Earth’s temperature to record highs, sustainability will only grow in overall importance.

Bamboo fiber composites show to be a competitive and environmentally friendly option to other construction materials, excelling in most performance based testing. Accessibility and the speed at which bamboo grows also make this an attractive choice from the standpoint of global warming and deforestation. With atmospheric carbon dioxide at record highs, it will be critically important to devise a way to remove this excess carbon dioxide from the air. Luckily, nature has provided a natural means to accomplish this through bamboo; however, additional action is still needed in order to counter mankind’s neglectful behavior.

37

This research investigated a previous case study that was done by SOM, and it was concluded that BFRC could not only be used to replace the Mass Timber elements that were proposed SOM but could do so with improved results. By utilizing the natural strength of the bamboo, the BFRC elements require smaller dimensions and therefore a lesser volume of material is needed for the structure. This results in an increase in leasable space, shorter floor-tofloor heights, and an overall lighter building. The reduced building weight leads to a smaller foundation size, which saves both time and money but also reduces carbon emissions. It was also concluded that by using BFRC for the structural elements of the building, the carbon emissions would be reduced far beyond that of a Timber structure and ultimately results in a structure that sequesters more carbon than is emitted in the construction of the building.

This cannot be said about any other construction material that exists today.

38

The amalgamation of polymer matrix and natural fibers yield composites possessing the best properties of each component.

This unique combination results in a high quality sustainable building material made from a plant that grows well and is available in most parts of the world. The extensive research from every field such as architecture, construction technology, biological engineering, genetic engineering, and cultivation are attempting to utilize bamboo fiber composites in the most effective way for the construction industry. The current era is the time for using bamboo fiber based composites for tall building construction.

“Climate change is real, it is happening right now. It is the most urgent threat facing our entire species, and we need to work collectively together and stop procrastinating. We need to support leaders around the world who do not speak for the big polluters or the big corporations, but who speak for all of humanity, for the indigenous people of the world, for the billions and billions of underprivileged people who would be most affected by this, for our children’s children, and for those people out there whose voices have been drowned out by the politics of greed. Let us not take this planet for granted.�

- Leonardo DiCaprio

39

40

GLOSSARY OF TERMS

Definition for tall building It is important to note that there is no universally accepted definition of a “tall building.” However, the Council on Tall Buildings and Urban Habitat (CTBUH) has set the following criteria required to qualify a building to be described as tall: 1. Height relative to context. According to the first criterion, the building should significantly exceed the general building heights of its surroundings. By this criterion, however, as the average height for buildings increases, what is considered tall at a particular time may not be considered tall at another time.

2. The second criterion for tallness implies verticality and states that the building should be slender enough so that it gives the appearance of a tall building, especially against low urban backgrounds. There are numerous large-footprint buildings, which are quite tall but their size/floor area rules them out as being classified as tall buildings.

This means that tall buildings are higher and thinner than “groundscrapers,” which also may be high, but tend to have a much larger footprint and bulkier appearance.

3. The third and relatively weak criterion--height-related building technologies--suggests that the building may be considered tall if it contains technologies attributed to tallness (e.g. specific vertical transport technologies, and structural systems efficient against lateral forces, etc.)

What is considered a tall building A building is an enclosed structure that has walls, floors, a roof, and usually windows.

A ‘tall building’ is a multi-story structure in which most occupants depend on elevators to reach their destinations.

Types of tall buildings The use of a building has considerable influence on its security and fire life safety needs.There are different types of high-rise buildings classified according to their primary use.

1. Office buildings.

An office building is a “ structure designed for the conduct of business, generally divided into individual offices and offering space for rent or lease. ” 2. Hotel buildings.

“ The term ‘ hotel ’ is an all-inclusive designation for facilities that provide comfortable lodging and generally, but not always food, beverage, entertainment, a business environment, and other ‘ away from home ’ services. ” 3. Residential and apartment buildings.

A residential building contains separate residences where a person may live or regularly stay. Each residence contains independent cooking and bathroom facilities and may be known as an apartment, a residence, a tenement, or a condominium. An apartment building is “ a building containing more than one dwelling unit. ” 4. Mixed-use buildings.

A mixed-use building may contain offices, apartments, residences, and hotel rooms in separate sections of the same building. Hotel-residences are another type of mixeduse occupancy. “Not only do hotel residences have kitchens and everything else an owner would expect in a typical abode, they also include amenities such as maid and room service, restaurants, and spas.”

41

The definition of building construction A techniques and industry involved in the assembly and erection of structures, primarily those used to provide shelter.

sometimes, on the narrow faces as well.

A cross-section of a CLT element has at least three glued layers of boards placed in orthogonally alternating orientation to the neighboring layers. In special configurations, consecutive layers may be placed Laminated Veneer Lumber in the same direction, giving a double layer Laminated veneer lumber is made up of to obtain specific structural capacities. CLT layers of wood veneers laminated together products are usually fabricated with three using a waterproof structural adhesive. The to seven layers. manufacturing process consists of rotary peeling a log into veneers that are then Fiber-based Composites dried and graded for strength and stiffness. Composites are two or more materials After the graded veneers are coated with with different physical or chemical propadhesive they are laid- up into a billet that erties – categorized as “matrix” or “reinis then fed into a hot press that cures the forcement” – combined in a way that toadhesive under heat and pressure. The gether they comprise a material, yet remain cured and compressed billet then leaves separate and distinct at some level because the hot press and is ripped into boards. they don’t fully merge or dissolve into one another [4]. One popular form of comLaminated Strand Lumber posites are fiber-reinforced polymer (FRP) Laminated strand lumber is a structur- composites which combine a polymer maal composite lumber manufactured from trix with a fiber reinforcement such as glass, strands of wood species or species com- carbon or other reinforcing fiber material. binations blended with an adhesive. The The advantage of using a composite mastrands are oriented parallel to the length terial lies in the fact that their constituent of the member and then pressed into mats materials retain their identities/properties using a steam injection press. (don’t dissolve or merge completely into each other) while acting together to proCross Laminated Timber vide a range of new benefits that wouldn’t CLT consists of several layers of boards be possible as an individual material. These stacked crosswise (at 90 degrees) and characteristics can include, but are not limglued together on their wide faces and, ited to having high strength, corrosion re-

42

sistance, high strength-to-weight ratio and directional strength.

Cellulose A complex carbohydrate, the chief component of the cell walls of most plants. It consists of long chain-like molecules of glucose which form micro fibrils.

Chemical properties These properties describe, how one kind of matter reacts with another kind of matter to form a new and different substance.

Compressive strength The maximum compressive stress that can be carried by the specimen during compression test.

Composite A composite material is a heterogeneous combination of two or more materials (reinforcing elements, fillers and binders), differing in form or composition on a macroscale. The combination results in a material that maximizes specific performance properties. The constituents do not dissolve or merge completely and therefore normally exhibit an interface between one another.

Culm The stem of a grass or sedges.

Density Hardness It is the ratio of the mass of the material to Hardness is a property of the material the volume of the material. which is characterized by the resistance offered by the material for indentation into it.

Ductility The hardness of a material is determined It is a measure of the deformation at frac- by either the size of an indentation made ture. It is the ability of the material to be by an indenting tool under a fixed load, or drawn into a wire. It indicates the ability of the load necessary to produce penetration a material to be plastically deformed such of the indenter to a predetermined depth. as formability during fabrication and relief of locally high stress at crack tips during Mechanical properties structural loading. Values for ductility are a The mechanical properties of the materifunction of gage length used. als are those which are associated with the ability of the material to resist mechanical Fiber forces and loads.

It is a long narrow flexible material, may be of animal, plant, mineral or synthetic origin. Modulus of elasticity The ratio of stress to the corresponding Flexural modulus strain below the proportional limit of the The ratio, within the elastic limit, of the ap- material. plied stress on a test specimen in flexure, to the corresponding strain in the outer- Shear strength most fibres of the specimen.

Shear strength means the maximum shear load divided by the shearing area before Flexural strength the initiation of the test.

Maximum flexural stress sustained by the test specimen during bending test. Flexural Strength strength can be defined as the maximum It is the ability of a material to resist exterstress in bending that can be withstood by nally applied forces at breaking or yielding. the outer fibres of a specimen before rup- The internal resistance offered by a part to turing. an externally applied force is called stress.

Stress When some external system of forces or loads acts on a body, the internal forces (equal and opposite) are set up at various sections of the body, which resist the external forces. This internal force per unit area at any section of the body is known as unit stress or simply stress.

Stiffness It is the ability of a material to resist deformation under stress. The modulus of elasticity is the measure of stiffness.

Tensile strength A measure of the ability of a material to withstand a longitudinal stress, expressed as the greatest stress that the material can stand without breaking.

Toughness It is the property of a material to resist fracture due to high impact loads like hammer blows. The toughness of the material decreases when is heated. It is measured by the amount of energy that a unit volume of material has absorbed after being stressed up to the point of fracture.

43

44

LIST OF FIGURES

Figure 1 Heavy congestion during rush hour in Shanghai, China.

Figure 2 Urban sprawl as a result of uncontrolled development around the periphery of cities.

Figure 3 Artist’s rendering of a city park demonstrating the beneďŹ ts that coincide with preserving open spaces within a city.

Figure 4 Photograph of downtown Bangkok, Thailand demonstrating the much improved environmental quality of the city.

Figure 5 Graphic illustration showing the global population over the past ten thousand years.

Figure 6 Embodied Energy of Construction Materials in the USA Figure 7 Transportation related carbon dioxide emissions including empty returns.

Figure 8 Conversion of raw materials into clinker produces approximately 0.55kg carbon dioxide per kg of clinker.

Figure 9 Manufacturing process for the production of steel.

Figure 10 Stadthaus building located in London, England.

Figure 11 Tamedia building located in Zurich, Switzerland.

Figure 12 Forte building located in Melbourne, Australia.

Figure 13 Satellite images showing deforestation within the Amazon rainforest over a ten year period.

Figure 14 Atmospheric concentrations of carbon dioxide over the past 400,000 years as expressed in units of parts per million by volume (ppm).

Figure 15 Material comparison of Bamboo Fiber Reinforced Composites with other construction materials.

Figure 16 Chemical composition of a mature bamboo plant.

Figure 17 The effect of different derivatives of silanes in addition to alkali treatment on water absorption properties of bamboo epoxy composites

45

Figure 18 Mechanical properties of bamboo fiber based reinforced composites.

Figure 19 Section cut showing the new design approach using mass timber to replace specific reinforced concrete elements.

Figure 20 Typical spandrel detail and floor slabs shown in red.

Figure 21 Typical wall joint detail and shear wall locations shown in red.

Figure 22 Typical column joint section detail and column locations shown in red.

Figure 23 Typical spandrel detail and floor slabs shown in red.

Figure 24 Comparison of CO2 emissions, volume of material required, and building weight based on the materials used for the structure.

Figure 25 Fire-resistance of members can be calculated, based on minimum thicknesses and the available thickness after charring.

Figure 26 Char layer insulates the inner core thereby limiting loss of structural integrity of the mass timber elements.

Figure 27 The insulation method consists of spray-applied materials or board materials to the structure to be protected.

Figure 28 Embedded steel plates are protected by the timber layer, which reduces the exposed area of steel to high temperatures.

Figure 29 In most cases automatic sprinkler systems operate to reduce temperatures and prevent fire development.

Figure 30 DuPont offer the most advanced heat resistance polymers in the industry and can withstand highs of 220º Celsius.

Figure 31 Worldwide distribution of bamboos.

Figure 32 The Bonn Challenge is an international movement to restore 370 million acres of degraded and deforested land by 2020.

Figure 33 Projected residential needs for the state of Florida over the next 25 years.

Figure 34 Greenworks Orlando neightborhood proposals.

46

REFERENCES

1. High-Rise Building Definition, Development, And Use. 1st ed. 2009. Web. 14 Feb. 2016.

2. Calder, Keith. The Historical Development Of The Building Size Limits In The National Building Code Of Canada. 1st ed. Richmond BC: Sereca Consulting Inc., 2015. Web. 14 Feb. 2016.

3. Craighead, Geoff. High-Rise Security And Fire Life Safety. Amsterdam: Butterworth-Heinemann/Elsevier, 2009. Print.

4. Benton Johnson, S.E., LEED® AP David Horos, and FIStructE William F. Baker. “STRUCTURE Magazine | Timber Tower Research Project”. Structuremag.org. N.p., 2016. Web. 14 Feb. 2016.

5. Cenews.com,. “A New Way To Build Tall | Civil + Structural ENGINEER”. N.p., 2016. Web. 14 Feb. 2016.

6. Scienceandanature.com,. “Science And Nature: Civil Engineering Basic Knowledge”. N.p., 2016. Web. 14 Feb. 2016.

7. Benton Johnson, S.E., LEED® AP David Horos, and FIStructE William F. Baker. “STRUCTURE Magazine | Timber Tower Research Project”. Structuremag. org. N.p., 2016. Web. 25 Dec. 2015.

8. Center for Immigration Studies,. “Outsmarting Smart Growth: Population Growth, Immigration, And The Problem Of Sprawl”. N.p., 2016. Web. 24 Dec. 2015.

9. Mdpi.com,. “Buildings | Free Full-Text | Tall Buildings And Urban Habitat Of The 21St Century: A Global Perspective | HTML”. N.p., 2016. Web. 14 Oct. 2015.

10. Bloomberg, Michael. Active Design Guidelines. 1st ed. New York: N.p., 2016. Web. 14 Jan. 2016.

11. Pank, Will. Tall Buildings And Sustainability. 1st ed. London: Corporation of London, 2002. Web. 1 Nov. 2015.

12. Wilson, Bev. The Environmental Impacts Of Sprawl: Emergent Themes From The Past Decade Of Planning Research. 1st ed. Champaign, IL: Department of Urban and Regional Planning, 2013. Print.

13. Mylott, Elizabeth. Urban-Rural Connections: A Review Of The Literature. 1st ed. 2016. Print.

14. The Urban Environment: Creating Livable And Sustainable Cities. 1st ed. Pearson Education, Inc, 2011. Print.

47

15. Resnik, David B. “Urban Sprawl, Smart Growth, And Deliberative Democracy”. Am J Public Health 100.10 (2010): 1852-1856. Web. 14 Jan. 2016.

16. Committee on Environmental Health, Tester JM. The built environment: designing communities to promote physical activity in children. Pediatrics.

2009;123(6):1591–1598 17. Mdpi.com,. “Buildings | Free Full-Text | Tall Buildings And Urban Habitat Of The 21St Century: A Global Perspective | HTML”. N.p., 2016. Web. 14 Feb. 2016.

18. Sjvblueprinttoolkit.weebly.com,. “Principle 7 - Preserve Open Space - SJV Blueprint Implementation Toolkit”. N.p., 2016. Web. 14 Nov. 2015.

19. Mdpi.com,. “Buildings | Free Full-Text | Tall Buildings And Urban Habitat Of The 21St Century: A Global Perspective | HTML”. N.p., 2016. Web. 4 Nov. 2015.

20. Resnik, David B. “Urban Sprawl, Smart Growth, And Deliberative Democracy”. Am J Public Health 100.10 (2010): 1852-1856. Web. 29 Nov. 2015.

21. Bhatta, B. Causes And Consequences Of Urban Growth And Sprawl. 1st ed. Springer-Verlag Berlin Heidelberg, 2010. Print.

22. Satterthwaite, David. The Transition To A Predominantly Urban World And Its Underpinnings. 1st ed. Endsleigh Street, London: N.p., 2016. Web. 1 Jan. 2016.

23. World Urbanization Prospects The 2007 Revision. 1st ed. New York, NY: N.p., 2008. Web. 5 Dec. 2015.

24. Globalchange.umich.edu,. “Human Populations”. N.p., 2016. Web. 14 Nov. 2015.

25. Desvaux, Dr. Martin. The Sust Ainability Of Human Populations: How Many People Can Live On Earth. 1st ed. 2007. Web. 18 Nov. 2015.

26. Ecology Global Network,. “Impact Of The Industrial Revolution | Ecology Global Network”. N.p., 2011. Web. 4 Jan. 2016.

27. Risen, Clay. Timber Tower Research Project. 1st ed. Chicago, Il: Popular Science, 2014. Web. 18 Nov. 2015.

28. The Dawn Of An Urban World. 1st ed. 2016. Web. 14 Jan. 2016.

29. Slideshare.net,. “Sus Tallbuildings”. N.p., 2016. Web. 17 Dec. 2015.

30. Menzies, Gillian. Embodied Energy Considerations For Existing Buildings. 13th ed. Historic Scotland Technical, 2011. Print.

31. Vestergaard Nielsen, Dr. Claus. Carbon Footprint Of Concrete Buildings Seen In The Life Cycle Perspective. 1st ed. Taastrup, Denmark: Danish Technological Institute, 2008. Web. 5 Jan. 2016.

32. Council on Foreign Relations,. “The Global Climate Change Regime”. N.p., 2016. Web. 1 Nov. 2015.

48

33. Energy Efficiency Improvement And Cost Saving Opportunities For Cement Making. 1st ed. US Environmental Protection Agency, 2013. Print.

34. LAGERBLAD, BJÖRN. Carbon Dioxide Uptake During Concrete Life Cycle. 1st ed. Stockholm: Swedish Cement and Concrete Research Institute, 2005. Web. 14 Jan. 2016.

35. GreenBiz,. “Climate And The Steel Industry”. N.p., 2006. Web. 16 Dec. 2015.

36. Timber Tower Research Project: Final Report. 1st ed. Chicago, Il: Skidmore, Owings, and Merrill, 2013. Print.

37. Dodoo, Ambrose. Life Cycle Primary Energy Use And Carbon Emission Of Residential Buildings. 1st ed. Östersund, Sweden: Mid Sweden University, 2011. Web. 14 Jan. 2016.

38. Buchanan, Andrew. Fire Resistance Of Timber Structures. 1st ed. National Institute of Standards and Technology, 2016. Print.

39. Akdart.com,. “Greenhouse Gases -- Water Vapor And Carbon Dioxide”. N.p., 2016. Web. 21 Dec. 2015.

40. Studentnunamazon.co.uk,. “Synopsis”. N.p., 2016. Web. 17 Nov. 2015.

41. Moutinho, Paulo. Tropical Deforestation And Climate Change. 1st ed. Amazon Institute for Environmental Research, 2005. Print.

42. Www3.epa.gov,. “Causes Of Climate Change | Climate Change | US EPA”. N.p., 2016. Web. 7 Dec. 2015.

43. Buildings And Climate Change. 1st ed. United Nations Environment Programme, 2009. Print.

44. Justfacts.com,. “Global Warming – Just Facts”. N.p., 2016. Web. 21 Nov. 2015.

45. “Bamboo In Construction: Is The Grass Always Greener?”. BuildingGreen. N.p., 2016. Web. 11 Oct. 2015.

46. Resnik, David B. “Urban Sprawl, Smart Growth, And Deliberative Democracy”. Am J Public Health 100.10 (2010): 1852-1856. Web. 15 Nov. 2015.

47. “Hidden Facts About Bamboo Equipment”. Peakpilates.com. N.p., 2016. Web. 30 Sept. 2015.

48. “Bamboo Helps Make Concrete Both Stronger & More Sustainable”. ForConstructionPros.com. N.p., 2016. Web. 11 Dec. 2015.

49. Kosmatka, Steven. Design And Control Of Concrete Structures. 14th ed. Portland Cement Association, 2016. Web. 11 Apr. 2016.

50. Buenaventura, Flora. “Growing Bamboo For Money And Healthy Environment”. Pcaarrd.dost.gov.ph. N.p., 2016. Web. 11 Nov. 2015.

51. Christine Baumann, Sandra Schneidereit. “Bamboo As A Building Material”. Bambus.rwth-aachen.de. N.p., 2016. Web. 1 Dec. 2015.

49

52. “Review Bamboo Fibre Reinforced Biocomposites: A Review”. Academia.edu. N.p., 2016. Web. 11 Jan. 2016.

53. Wang, X. et al. “Cell Wall Structure And Formation Of Maturing Fibres Of Moso Bamboo (Phyllostachys Pubescens) Increase Buckling Resistance”. Journal of The Royal Society Interface 9.70 (2011): 988-996. Web. 30 Nov. 2015.

54. “Save Time And Improve Your Marks With Citethisforme, The No. 1 Citation Tool”. Cite This For Me. N.p., 2016. Web. 11 Nov. 2015.

55. “Polymer Science And Engineering”. (1994): n. pag. Web. 11 Jan. 2016.

56. Chemistry For Tomorrow’s World. 1st ed. RSC, 2009. Web. 11 Nov. 2015.

57. “On Using Bamboo As Alternative To Steel | Tribe LAB”. Tribelab.org. N.p., 2015. Web. 11 Dec. 2015.

58. “Lightweight Composites Reinforced By Agricultural Byproducts - ACS Symposium Series (ACS Publications)”. ACS Symposium Series (2016): n. pag.

Web. 1 Dec. 2015.

59. “Mechanical, Physical And Tribological Characterization Of Nano-Cellulose Fibers Reinforced Bio-Epoxy Composites: An Attempt To Fabricate And Scale The ‘Green’ Composite”. Sciencedirect.com. N.p., 2016. Web. 2 Jan. 2016.

60. Kalia, Susheel et al. “Cellulose-Based Bio- And Nanocomposites: A Review”. International Journal of Polymer Science 2011 (2011): 1-35. Web. 11 Jan. 2016.

61. Célino, Amandine et al. “The Hygroscopic Behavior Of Plant Fibers: A Review”. Front. Chem. 1 (2014): n. pag. Web. 31 Dec. 2015.

62. “Biocomposites Reinforced-With-Natural-Fibers-2000-2010 2012-Progress-…”. Slideshare.net. N.p., 2016. Web. 19 Dec. 2015.

63. Timber Tower Research Project. 1st ed. Chicago: Skidmore, Owings, and Merrill, 2013. Web. 11 Dec. 2015.

64. Buildings And Climate Change. 1st ed. Paris, France: United Nations Environment Programme, 2009. Web. 11 Oct. 2015.

65. “Review Of Methods To Assess, Design For, And Mitigate Multiple Hazards: Journal Of Performance Of Constructed Facilities: (ASCE)”. Journal of Performance of Constructed Facilities (2016): n. pag. Web. 11 Feb. 2016.

66. Quiter, James. Guidelines For Designing Fire Safety In Very Tall Buildings. 1st ed. Society of Fi re Protection Engineers, 2012. Web. 11 Feb. 2016.

67. Beyler, Craig. Fire Resistance Testing For Performance-Based Fire Design Of Buildings. 1st ed. Quincy, Massachusetts: Fire Protection Research Foundation, 2007. Print.

68. Fire Safety Of Bonded Structural Timber Elements. 1st ed. ETA Zurich, 2014. Web. 3 Mar. 2016.

50

69. Technical Guide For The Design And Construction Of Tall Buildings. 1st ed. FP Innovations, 2013. Print.

70. Green, Michael. The Case For Tall Wood Buildings. 1st ed. Vancouver: Michael Green Architects, 2016. Print.

71. McAllister, Therese, and W. G Corley. World Trade Center Building Performance Study. Washington, D.C.: Federal Emergency Management Agency, Federal Insurance and Mitigation Administration, 2002. Print.

72. Barber, David, and Robert Gerard. “Summary Of The Fire Protection Foundation Report - Fire Safety Challenges Of Tall Wood Buildings”. Fire Science Reviews 4.1 (2015): n. pag. Web. 1 Feb. 2016.

73. Stability, Polymer, and Polymer Stability. “Polymer Degradation And Stability - Journal - Elsevier”. Journals.elsevier.com. N.p., 2016. Web. 14 Jan. 2016.

74. Fire-Safe Polymers And Polymer Composites. 1st ed. Washington D.C.: US Department of Transportation, 2004. Print.

75. “Bamboo - Wikibooks, Open Books For An Open World”. En.wikibooks.org. N.p., 2016. Web. 1 Dec. 2015.

76. “Bamboo”. America.pink. N.p., 2016. Web. 14 Dec. 2015.

77. Global Climate Change: National Security Implications. 1st ed. United States Government, 2008. Print.

78. “Outsmarting Smart Growth: Population Growth, Immigration, And The Problem Of Sprawl”. Center for Immigration Studies. N.p., 2016. Web. 14 Jan. 2016.

79. “Smart Communities Network: Green Buildings Success Stories”. Smartcommunities.ncat.org. N.p., 2016. Web. 2 Jan. 2016.

80. “Green Works Orlando”. Green Works Orlando. N.p., 2016. Web. 14 Jan. 2016.

51