Using Bamboo Bracing to Create Earthquake-Resistant Homes
Solving the huge issue of earthquakes destroying lives in Indonesia
Imagine you are in your house, cooking dinner, going about your day. Suddenly the earth beneath you begins to shake. You rush to find shelter as the walls and roof of your house rumble. A few minutes later, the rumbling stops, leaving you shaken but relatively unscathed. However, for hundreds of thousands of Indonesians, this would not be the case.
Every year, an earthquake with a magnitude 6 or greater strikes Indonesia [source]. They displace more than 100 thousand people, as their homes crumble and crash around them. Thousands of people die trying to escape. These yearly events also have a major economic impact, often costing between 500 million and 1 billion USD in economic losses for Indonesia [source].
Earthquakes are especially damaging as they are instantaneous events. They are much more difficult to track and prepare for compared to cyclones, tornadoes, and floods. In the space of minutes, homes are destroyed, lives are lost, and the years of progress for villages are destroyed.
Poor construction affects rural areas the most
Over 115 million Indonesians continue to live in homes that are not protected from earthquakes, primarily in rural areas. The lack of earthquake resistance in Indonesian homes is a direct result of the materials they use. A shortage of traditional wood building materials led Indonesians to turn to new options such as brick and concrete. However, they had little knowledge of how to use these properly. The result was homes that had unstable foundations, unreinforced roofs, and weak, brittle walls. When earthquakes hit, these homes were not only unable to withstand seismic forces but became very dangerous to the families inside.
Current solutions focus on rebuilding, not preventing
Solutions to this issue have come from a number of private-sector organizations. The organizations Build Change and Ramboll have both worked to rebuild houses to be more earthquake-resistant. Build Change focuses on empowering rural residents to create higher-quality bricks that withstand greater forces [source]. Ramboll has piloted bamboo-based houses to replace ones made of the often misused brick and concrete [source].
However, these solutions are both focused on rebuilding after earthquakes happen. Because earthquakes strike without warning, people are often unable to escape as their home crumbles around them. Major earthquakes end up killing hundreds of people each year in this way.
The current solutions only kick in after these deaths have occurred. In order to save these lives, rural residents need to retrofit their existing homes. Their homes need to be able to withstand earthquake forces long enough for them to escape.
There is no good way to retrofit
Retrofitting technologies have existed for many years and have been applied to urban cities. However, they all face difficulties reaching rural areas. The table below compares different types of retrofitting technologies [source]:
These technologies are plagued by two major issues. The first is that they rely on imported materials, such as concrete or polymers. These can be costly to get to rural areas. The second is that applying these materials often requires construction expertise. Without this knowledge, residents cannot use the technology or will use it improperly.
A new solution is needed that uses abundant materials and empowers rural residents to apply the technology on their own.
Harnessing the power of bamboo to strengthen walls
The main problems with existing retrofitting solutions are that they are made of costly materials and that they require skilled workers to assemble. Our solution solves this problem by using a ubiquitous and easy-to-assemble material: bamboo. Walls are reinforced by attaching lattice structures of bamboo to them. The process is as follows:
- Start with a brick-and-mortar wall
- Drill a lattice of holes into the mortar
- Attach ties through the holes
- Lay bamboo strips vertically and tie them to the wall
- Lay bamboo strips horizontally and tie them to the wall
- Apply the finishing adhesive, made by mixing sand, cement, and epoxy resin
How does this compare to other retrofitting methods?
Materials required
Bamboo is found naturally in rural Indonesia and can be easily obtained by residents. All that’s needed to create wall reinforcements are ties, which can also be made from bamboo, and an adhesive made out of common materials: sand, cement, and a little epoxy resin. Unlike any other options, the main material, bamboo, does not have to be imported. This drastically reduces costs.
Cost
The cost of bamboo is low, as the residents can obtain it directly from the environment around them. If it is not readily available, the cost of the necessary bamboo is around $75 USD for 15 kg, roughly the amount required [source]. The finishing coat of adhesive costs around $10/kg, making the whole project much more affordable than alternatives.
Accessibility to rural areas
Bamboo braces can be easily assembled by rural workers in a matter of days. This means that they’re scalable to the millions of houses at risk from earthquakes. Residents will not have to rely on external support to protect themselves.
Efficiency
Bamboo braces are designed to strengthen the walls of a house so that it does not collapse immediately. The success of these braces was shown in a study by Habieb et al, where the above brace method was tested in a pushover shear test [source]. In this test, a force was slowly applied to the wall parallel to the mortar, as shown below. This simulated typical earthquake conditions, where such force would be caused by shaking ground.
The strengthened wall was able to consistently withstand more force than the unstrengthened one. More importantly, as shown in the photos below, the strengthened wall did not collapse in the same way. Instead of collapsing nearly immediately, the wall shifted but held its form.
This indicates that, in an earthquake event, the wall would be able to remain standing, allowing families to escape their homes before a complete collapse occurs. This would save their lives, allowing them the ability to build back their homes better than before.
Bamboo bracing will save thousands of lives
In the worst earthquakes, around 10,000 homes have been destroyed [source]. At 4 people per home, this leaves 40,000 people needing to escape. This has left between 1000 and 5000 crushed beneath collapsed homes. Without bamboo bracing, 1 in 8 residents die in their own homes.
With bamboo bracing, people are given twice as long to escape their homes. This extra time could allow the majority of residents to escape. This would save 800–4000 lives each year.
It would also give residents the opportunity to seek help from existing rebuilding organizations. Often, after a major earthquake, humanitarian organizations seek to rebuild homes in the affected areas in a way that is more safe [source]. Bamboo bracing will allow those affected to live to see their homes rebuilt.
Financial incentives are already in place
Bamboo bracing is an effective technology ready to be used by rural residents. Better yet, the incentives for doing so already exist. In 2006, the Indonesian government started the BSPS (Bantuan Stimulan Perumahan Swadaya) program, which aimed to provide financial assistance to support retrofitting efforts, up to $1500 USD per home.
However, this has been a slow project, reaching only 1% of substandard houses each year. This is largely due to the high cost of retrofitting technologies, as well as issues with reaching many rural areas [source].
Bamboo bracing is a perfect technology to fill these gaps, as it utilizes cheap and available materials. Now, investing in it is even easier for rural families, as they can be subsidized by the government. Because residents end up doing the work themselves, they can also recuperate the potential cost of taking a few days from their livelihoods.
Bamboo bracing is the way forward for families that risk their lives every day, simply by living in poorly built houses. All that’s left is to start bringing this technology to the ground, for the benefit of all.
Lots of credit to Aliyan, Markus, and Miguen for working on this project together and writing this together !
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