Bamboo construction involves the use of bamboo as a building material for scaffolding, bridges, houses and buildings. Bamboo, like wood, is a natural composite material with a high strength-to-weight ratio useful for structures. [1] Bamboo's strength-to-weight ratio is similar to timber, and its strength is generally similar to a strong softwood or hardwood timber. [2] [3]
In its natural form, bamboo as a construction material is traditionally associated with the cultures of South Asia, East Asia, the South Pacific, and Central and South America. In China and India, bamboo was used to hold up simple suspension bridges, either by making cables of split bamboo or twisting whole culms of sufficiently pliable bamboo together. One such bridge in the area of Qian-Xian is referenced in writings dating back to 960 AD and may have stood since as far back as the third century BC, due largely to continuous maintenance.
Bamboo has also long been used as scaffolding; the practice has been banned in China for buildings over six stories, but is still in continuous use for skyscrapers in Hong Kong. [4] In the Philippines, the nipa hut is a fairly typical example of the most basic sort of housing where bamboo is used; the walls are split and woven bamboo, and bamboo slats and poles may be used as its support. In Japanese architecture, bamboo is used primarily as a supplemental and/or decorative element in buildings such as fencing, fountains, grates and gutters, largely due to the ready abundance of quality timber. [5]
In parts of India, bamboo is used for drying clothes indoors, both as a rod high up near the ceiling to hang clothes on, and as a stick wielded with acquired expert skill to hoist, spread, and to take down the clothes when dry. It is also commonly used to make ladders, which apart from their normal function, are also used for carrying bodies in funerals. In Maharashtra, the bamboo groves and forests are called Veluvana, the name velu for bamboo is most likely from Sanskrit, while vana means forest. Furthermore, bamboo is also used to create flagpoles.
In Central and South America, bamboo has formed an essential part of the construction culture. [6] Vernacular forms of housing such as bahareque have developed that use bamboo in highly seismic areas. When well-maintained and in good condition, these have been found to perform surprisingly well in earthquakes. [7]
Over the past few decades, there has been a growing interest in using bamboo round poles for construction, primarily because of its sustainability. Famous bamboo architects and builders include Simón Velez, Marcelo Villegas, Oscar Hidalgo-López, Jörg Stamm, Vo Trong Nghia, Elora Hardy and John Hardy. To date, the most high-profile bamboo construction projects have tended to be in Vietnam, Bali (Indonesia), China and Colombia. The greatest advancements in structural use of bamboo have been in Colombia, where Universities have been conducting significant research into element and joint design and large high-profile buildings and bridges have been constructed. [6] In Brazil, bamboo have been studied for more than 40 years at the Pontifical Catholic University of Rio de Janeiro PUC-Rio for structural applications. Some important results are the tensegrity bamboo structures, the bamboo bicycles, the bamboo space structure with rigid steel joints, the deployable bamboo structure pavilions with flexible joints [8] [9] and the bamboo active bending-pantographic amphitheater structure [10] [11] developed by Bambutec Design company.
The first structural design codes for bamboo in-the-round were published by ISO in 2004 (ISO 22156 Bamboo - structural design, ISO 22157-1 Bamboo – Determination of Physical and Mechanical properties part 1 and ISO 22157-2 Bamboo – Determination of Physical and Mechanical properties part 2: Laboratory manual. Colombia was the first country to publish a country-specific code in the structural use of bamboo (NSR-10 G12). Since then, Ecuador, Peru, India and Bangladesh have all published codes, [12] however the Colombian code is still widely considered to be the most reliable and comprehensive.
Heat and pressure is sometimes traditionally used to form curved shapes in bamboo. [13]
A typical bamboo shows a nonlinear stress-strain behaviour. It can restrain strain of up to 0.05 until it breaks at which the stress level can be about 300 MPa. [14]
Bamboo is more susceptible to decay than timber, due to a lack of natural toxins [15] and its typically thin walls, which means that a small amount of decay can mean a significant percentage change in capacity. There are three causes of decay: beetle attack, termite attack and fungal attack (rot). [16] [17] Untreated bamboo can last 2–6 years internally, and less than a year if exposed to water. [16] [15]
In order to protect bamboo from decay, two design principles are required: [16]
Both principles must be applied to a design in order to protect bamboo. Boron by itself is inadequate to protect against rot, and it will wash out if exposed to water. [16]
Modern fixed preservatives may be used as alternatives to boron such as copper azole, however little bamboo has been reliably tested using these methods to date. In addition, they tend to be more hazardous for the treatment workers and the end user, and therefore are less appropriate for developing countries, which is where bamboo is currently mostly used. [16]
Natural forms of bamboo treatment such as soaking in water and exposing to smoke may provide some limited protection against beetles, however, there is little evidence to show they are effective against termites and rot, and are therefore not typically used in modern construction. [18]
Bamboo can be cut and laminated into sheets and planks. This process involves cutting stalks into thin strips, planing them flat, and drying the strips; they are then glued, pressed and finished. Long used in China and Japan, entrepreneurs started developing and selling laminated bamboo flooring in the West during the mid-1990s; products made from bamboo laminate, including flooring, cabinetry, furniture and even decorations, are currently surging in popularity, transitioning from the boutique market to mainstream providers such as Home Depot. The bamboo goods industry (which also includes small goods, fabric, etc.) is expected to be worth $25 billion by 2012. [19] The quality of bamboo laminate varies among manufacturers and varies according to the maturity of the plant from which it was harvested (six years being considered the optimum).
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There are a number of common myths and misconceptions surrounding the use of bamboo for construction.
This misunderstanding may have occurred due to the following reasons: [3]
If some fibres of some species show relatively high strengths, following international practice, the design strength that can be safely used is closer to 5–10% of this value, to account for the variability of the strengths.
As described above, bamboo needs to be kept dry in order to protect it from rot, and many existing bamboo structures are showing signs of rot because they did not follow the principles of durability by design. [20]
Bamboo is a brittle material and therefore by itself is unable to absorb energy in earthquakes. There is also no advantage of its low stiffness in terms of the performance of bamboo buildings in earthquakes. Instead, bamboo structures are primarily good in earthquakes because:
Plain bolted connections can show brittle behavior due to longitudinal splitting of bamboo culms. Providing confinement to bamboo culms at the connection zones increases resistance to this failure mode and brings significant improvement to strength and ductility.
More importantly, bolted connections display predictable yielding. [22] [23] [24] This is vital for performing a rational engineered design. [25] The bolts are also widely available, easy-to-use and versatile. [26]
This misconception stems from the original idea that bamboo is stronger than steel, and hence could simply replace steel in reinforced concrete.
In reality, bamboo does not function well as a replacement for steel in concrete for the following reasons: [27]
Bamboo was used for the structural members of the India pavilion at Expo 2010 in Shanghai. The pavilion is the world's largest bamboo dome, about 34 m (112 ft) in diameter, with bamboo beams/members overlaid with a ferro-concrete slab, waterproofing, copper plate, solar PV panels, a small windmill, and live plants. A total of 30 km (19 mi) of bamboo was used. The dome is supported on 18-m-long steel piles and a series of steel ring beams. The bamboo was treated with borax and boric acid as a fire retardant and insecticide and bent in the required shape. The bamboo sections were joined with reinforcement bars and concrete mortar to achieve the necessary lengths. [28]
Bamboo has been used successfully for housing in Costa Rica, Ecuador, El Salvador, Colombia, Mexico, Nepal and the Philippines. [2] [20] [29] An appropriate way of using bamboo for housing is considered to be "bahareque encemendato", or "improved bahareque"/"engineered bahareque". [30] This method takes the Latin America vernacular construction system bahareque (a derivative of wattle and daub) and engineers it, making it considerably more durable and resistant to earthquakes and typhoons.
Panyaden International School in northern Thailand expanded its campus with a bamboo sports hall designed by Chiangmai Life Architects. Inspired by the lotus flower, the hall spans 782 square meters and includes courts for various sports and a liftable stage. The innovative design uses prefabricated bamboo trusses spanning over 17 meters, ensuring the structure can withstand high-speed winds and earthquakes. The hall's natural ventilation and insulation provide year-round comfort, while its use of bamboo maintains a zero-carbon footprint. [31]
Bamboo used for construction purposes must be harvested when the culms reach their greatest strength and when sugar levels in the sap are at their lowest, as high sugar content increases the ease and rate of pest infestation.
Harvesting of bamboo is typically undertaken according to the following cycles:
Bamboos are a diverse group of mostly evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in the case of Dendrocalamus sinicus having individual stalks (culms) reaching a length of 46 meters, up to 36 centimeters in thickness and a weight of up to 450 kilograms. The internodes of bamboos can also be of great length. Kinabaluchloa wrayi has internodes up to 2.5 meters in length. and Arthrostylidium schomburgkii has internodes up to 5 meters in length, exceeded in length only by papyrus. By contrast, the stalks of the tiny bamboo Raddiella vanessiae of the savannas of French Guiana measure only 10–20 millimeters in length by about two millimeters in width. The origin of the word "bamboo" is uncertain, but it probably comes from the Dutch or Portuguese language, which originally borrowed it from Malay or Kannada.
Structural engineering is a sub-discipline of civil engineering in which structural engineers are trained to design the 'bones and joints' that create the form and shape of human-made structures. Structural engineers also must understand and calculate the stability, strength, rigidity and earthquake-susceptibility of built structures for buildings and nonbuilding structures. The structural designs are integrated with those of other designers such as architects and building services engineer and often supervise the construction of projects by contractors on site. They can also be involved in the design of machinery, medical equipment, and vehicles where structural integrity affects functioning and safety. See glossary of structural engineering.
Reinforced concrete, also called ferroconcrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ductility. The reinforcement is usually, though not necessarily, steel bars (rebar) and is usually embedded passively in the concrete before the concrete sets. However, post-tensioning is also employed as a technique to reinforce the concrete. In terms of volume used annually, it is one of the most common engineering materials. In corrosion engineering terms, when designed correctly, the alkalinity of the concrete protects the steel rebar from corrosion.
Rebar, known when massed as reinforcing steel or steel reinforcement, is a steel bar used as a tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concrete under tension. Concrete is strong under compression, but has low tensile strength. Rebar significantly increases the tensile strength of the structure. Rebar's surface features a continuous series of ribs, lugs or indentations to promote a better bond with the concrete and reduce the risk of slippage.
Engineered wood, also called mass timber, composite wood, human-made wood, or manufactured board, includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles, fibres, or veneers or boards of wood, together with adhesives, or other methods of fixation to form composite material. The panels vary in size but can range upwards of 64 by 8 feet and in the case of cross-laminated timber (CLT) can be of any thickness from a few inches to 16 inches (410 mm) or more. These products are engineered to precise design specifications, which are tested to meet national or international standards and provide uniformity and predictability in their structural performance. Engineered wood products are used in a variety of applications, from home construction to commercial buildings to industrial products. The products can be used for joists and beams that replace steel in many building projects. The term mass timber describes a group of building materials that can replace concrete assemblies.
Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with recent experiences with large earthquakes near urban centers, the need of seismic retrofitting is well acknowledged. Prior to the introduction of modern seismic codes in the late 1960s for developed countries and late 1970s for many other parts of the world, many structures were designed without adequate detailing and reinforcement for seismic protection. In view of the imminent problem, various research work has been carried out. State-of-the-art technical guidelines for seismic assessment, retrofit and rehabilitation have been published around the world – such as the ASCE-SEI 41 and the New Zealand Society for Earthquake Engineering (NZSEE)'s guidelines. These codes must be regularly updated; the 1994 Northridge earthquake brought to light the brittleness of welded steel frames, for example.
Glued laminated timber, commonly referred to as glulam, is a type of structural engineered wood product constituted by layers of dimensional lumber bonded together with durable, moisture-resistant structural adhesives so that all of the grain runs parallel to the longitudinal axis. In North America, the material providing the laminations is termed laminating stock or lamstock.
Natural building or ecological building is a discipline within the more comprehensive scope of green building, sustainable architecture as well as sustainable and ecological design that promotes the construction of buildings using sustainable processes and locally available natural materials.
Steel frame is a building technique with a "skeleton frame" of vertical steel columns and horizontal I-beams, constructed in a rectangular grid to support the floors, roof and walls of a building which are all attached to the frame. The development of this technique made the construction of the skyscraper possible. Steel frame has displaced its predecessor, the iron frame, in the early 20th century.
Guadua is a Neotropical genus of thorny, clumping bamboo in the grass family, ranging from moderate to very large species.
Structural steel is a category of steel used for making construction materials in a variety of shapes. Many structural steel shapes take the form of an elongated beam having a profile of a specific cross section. Structural steel shapes, sizes, chemical composition, mechanical properties such as strengths, storage practices, etc., are regulated by standards in most industrialized countries.
Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment, transported to the construction site and maneuvered into place; examples include precast beams, and wall panels, floors, roofs, and piles. In contrast, cast-in-place concrete is poured into site-specific forms and cured on site.
This is an alphabetical list of articles pertaining specifically to structural engineering. For a broad overview of engineering, please see List of engineering topics. For biographies please see List of engineers.
A gridshell is a structure which derives its strength from its double curvature, but is constructed of a grid or lattice.
The history of structural engineering dates back to at least 2700 BC when the step pyramid for Pharaoh Djoser was built by Imhotep, the first architect in history known by name. Pyramids were the most common major structures built by ancient civilizations because it is a structural form which is inherently stable and can be almost infinitely scaled.
Engineered bamboo is a set of composite products produced from bamboo. It is designed to be a replacement for wood or engineered wood, but is used only when high load bearing strength is not required because building standards for this type of use have not been agreed by regulatory bodies. Engineered bamboo comes in several different forms, including bamboo scrimber and laminated bamboo, which has three times the structural capacity as normal timber and is defined and regulated by the ASTM International Standards.
This glossary of structural engineering terms pertains specifically to structural engineering and its sub-disciplines. Please see glossary of engineering for a broad overview of the major concepts of engineering.
Bahareque, also spelled bareque, is a traditional building technique used in the construction of housing by indigenous peoples. The constructions are developed using a system of interwoven sticks or reeds, with a covering of mud, similar to the systems of wattle and clay structures seen in Europe. This technique is primarily used in regions such as Caldas, which is one of the 32 departments of Colombia.
The reinforcement of 3D printed concrete is a mechanism where the ductility and tensile strength of printed concrete are improved using various reinforcing techniques, including reinforcing bars, meshes, fibers, or cables. The reinforcement of 3D printed concrete is important for the large-scale use of the new technology, like in the case of ordinary concrete. With a multitude of additive manufacturing application in the concrete construction industry—specifically the use of additively constructed concrete in the manufacture of structural concrete elements—the reinforcement and anchorage technologies vary significantly. Even for non-structural elements, the use of non-structural reinforcement such as fiber reinforcement is not uncommon. The lack of formwork in most 3D printed concrete makes the installation of reinforcement complicated. Early phases of research in concrete 3D printing primarily focused on developing the material technologies of the cementitious/concrete mixes. These causes combined with the non-existence of codal provisions on reinforcement and anchorage for printed elements speak for the limited awareness and the usage of the various reinforcement techniques in additive manufacturing. The material extrusion-based printing of concrete is currently favorable both in terms of availability of technology and of the cost-effectiveness. Therefore, most of the reinforcement techniques developed or currently under development are suitable to the extrusion-based 3D printing technology.
Tensioned stone is a high-performance composite construction material: stone held in compression with tension elements. The tension elements can be connected to the outside of the stone, but more typically tendons are threaded internally through a drilled duct.
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