Is Bamboo a Safe Construction Material in Natural Disasters Like Earthquakes?
Is Bamboo a Safe Construction Material in Natural Disasters Like Earthquakes?
You may have heard about the use of bamboo in the temporary shelters created in humanitarian aid efforts after an earthquake, but bamboo can actually be very valuable in the construction of buildings that can withstand earthquakes. Why should we look towards bamboo as a temporary solution after a disaster when we could save lives by building with it in the first place? Bamboo is a great option for building homes and shelters in earthquake-prone regions, given that the structures are well designed, constructed, and maintained. From old traditional structures to modern builds, several examples from across the globe have proven themselves against the very forces of nature that have brought down concrete and brick buildings.
Bamboo Structures’ Anti-Seismic Properties
- Bamboo’s good strength-to-weight ratio means that the structure is subjected to lower forces during earthquakes and, in the case of collapse, the light bamboo poses less of a risk to the occupants;
- Bamboo is flexible due to its tensile strength, its fibrous morphology and its lightweight nature, make it resistant to lateral shocks from earthquakes;
- Bamboo’s bi-composition of lignin and vascular bundles acts to dampen vibrations. Each of bamboo’s primary constituents has a different density and therefore a different frequency at which they want to vibrate. When vibrations go through the bamboo, these two frequencies cancel out one another which generates stability in the culm;
- Bamboo’s joinery systems, such as nails, traditional carpentry connections and rope, can be made to absorb the shocks of earthquakes and distribute the forces so that the different parts of the structure move together;
- Bamboo can be accompanied with other materials, such as mud, vegetable materials and other daubs, which can increase the structure’s ability to absorb energy.
Impact of Design on Building Safe Structures
Like everything in the construction world, designing bamboo housing is context dependent. In some earthquake prone regions where bamboo is native and forms part of the vernacular architecture and the local labour skill, it can be an affordable, durable and highly renewable material to push forward. There are also some design criteria that when followed, along with proper selection and treatment of the bamboo, can increase the safety of the structures.
As seen in examples around the world, bracing the walls of the structure using different systems such as shear walls and moment frames can help to resist earthquake loads. Regardless of the constructive system chosen, good design for earthquakes requires keeping the structure, and particularly the roof, lightweight in order to reduce the force it will undertake.
Even the form of the structure can impact its reaction to earthquakes. For example, overly long floor spans can decrease the structure’s efficiency while circular structures can be optimal, as observed in many vernacular housing models. Good design also goes down to the details – using tried and tested joinery can successfully distribute loads and shocks, as well as connecting and securing each component of the structure well. The ideal design of earthquake-resistant bamboo structures considers all of these criteria, uses healthy bamboo, and considers the context in which it is made.
Successful Global Examples
A popular example of bamboo housing that has been used in earthquake-prone regions across South America is bahareque. Some examples of bahareque construction include cladding with bamboo splits, canes or twigs and daubing using mud or cement, with roofs made of clay tiles.
A Bamboo U Online Course facilitator, Luis Felipe Lopez, created the Colombian bahareque building code with the Colombian Association of Seismic Engineering (AIS), a code which was adopted in many other countries to push forward the use of these earthquake-safe bamboo houses. Recently, Luis Felipe and his team and collaborators have adapted this traditional bahareque system to build hundreds of safe homes in the Philippines, a country extremely prone to an array of natural disasters.
This video shows an overview of some of the work, from lab to field, that the Hilti Foundation does:
The Future Of Earthquake-Safe Bamboo Houses
Bamboo can be a safe construction material in earthquake-prone areas. To encourage its use it is important to spread knowledge about how to select and treat bamboo to communities. It is also exciting to see bamboo increasingly included in building codes around the world. During a live talk in our latest Online Course, Luis Felipe explained the importance of these codes, many of which he has led and contributed to.
Sources:
- Dezeen, Ramboll uses bamboo to build earthquake-resistant housing in Indonesia [link]
- Better Bamboo Buildings, Sebastian Kaminski – Bamboo Buildings in Earthquakes [link]
- Building with Bamboo, Gernot Minke (book)
- INBAR, Bamboo – a Strategic Resource for Earthquake-Prone Regions [link]
- IPIRTI, Seismic performance of Bamboo housing– an overview [link]
- Jagadish Vengala and Raghunath Seshagiri Rao, Sustainable bamboo housing for the earthquake-prone areas [link]
This article was originally published here by Bamboo U, a bamboo architecture and design enterprise that focuses on sharing sustainable ways of building. Bamboo courses are available on their campus in Bali, Indonesia, and Online, lead in collaboration with the renowned design firm IBUKU and bamboo experts from around the world. From growing bamboo to treatment methods, bamboo design and model making, engineering, carpentry, and construction: their workshops cover all there is to know about bamboo building and design. Find out more & join a bamboo workshop here.