Recommendations for constructing shelter with bamboo in Coxs

Recommendations for constructing shelter with bamboo in Cox’s Bazar Shelter Meeting 18, Geneva, 6 th July 2018 Seb Kaminski, Arup As part of IOM Lead Shelter Sector, Cox’s Bazar

Contents 1. Cyclonic winds in region, and recommended design wind loads. 2. How the bamboo shelters are likely to behave in strong winds. 3. Recommended key messages for constructing bamboo shelters against wind. 4. Recommendations for treating bamboo in this context.

Cyclonic winds in region • 1991 Bangladesh cyclone killed 138, 000 and left 10 million homeless. • Historic wind data for region is minimal and unreliable – local advice would be useful. Anemometer in camp? • Bangladesh code wind is for a “super cyclonic storm” with 1 min sustained wind speeds in open sea of >328 km/h: this has a return period of ~50 years. • For upgraded shelters, mid-term shelters and community structures, we recommend a minimum of 187 km/h (extremely severe cyclonic storm): this has a return period of ~20 years. • There is on average one cyclone every 3 years in the region. See Arup Technical Guidance Note 01: Wind loading for the design of emergency shelters, mid-term shelters and community structures

Debris impact 4 NOAA (1992) Hurricane Andrew's 160+ mph winds drive a sheet of plywood through the trunk of a palm tree in Homestead, FL. Copyright: Public Domain. [ONLINE]. Available at: https: //commons. wikimedia. org/wiki/File: Andrew_plywood. gif. (Accessed March 2018).

How the bamboo shelters are likely to behave in strong winds Gale Storm Hurricane Key Beaufort Scale: Wind speed in open sea (1 minute gust): North Indian Ocean Scale (India Meteorological Department) See Arup Technical Guidance Note 02: Structural Assessment of Emergency Shelters Under Wind Loading

How the bamboo shelters are likely to behave in strong winds

How the bamboo shelters are likely to behave in strong winds Gale Storm Hurricane Expected to occur yearly?

How the bamboo shelters are likely to behave in strong winds Most likely failures are: • Without rope cross-bracing: base of embedded columns (snap or pull -out of ground). • With rope cross-bracing and guy ropes: pull-out of ground.

7 key messages for constructing bamboo shelters against wind

Durability of bamboo in CXB Untreated Risk from: • Termites. • Beetles. • Rot (fungi). Internal, no insect risk 30+ years Internal, high insect risk 2 -6 years External above ground 0. 5 -4 years External in ground contact <0. 5 years Fungus on Log in Garston Wood by Trish Steel is licensed under CC BY-SA 2. 0 https: //commons. wikimedia. org/wiki/File: Fungus_on_Log_in_Garston_Wood _-_geograph. org. uk_-_313089. jpg

Current state of bamboo in CXB Bamboo is currently: • Untreated. • Often immature. • Green. All species are very vulnerable.

1) Durability by design Shelter Cluster Ecuador

2 a) Treatment by water soaking • Reduces beetle risk. • No effect on termite or rot. Considering lab termite tests to determine whether saltwater soaking has any further benefit.

2 b) Treatment by boron • Eliminates beetle risk. • Eliminates termite risk. • No effect on rot. • Can be washed out.

Never cast bamboo into concrete foundations • Does not work, even if painted in tar/oil. • May even make rotting more likely. • Always allow bamboo to breath. Possible forthcoming Arup Technical Guidance Note 03: Durability of Bamboo and Treatment

Summary Existing shelters • • Very vulnerable to winds Lifespan <1 year Improved shelters Key improvements • • • Stronger structure (wall bracing, roof bracing, better connections). Concrete footings. Boron treated bamboo. • • Less vulnerable to winds (~10 x stronger). Lifespan of structure (ignoring sheeting): potentially 20+ years.

Thank you Any technical questions please feel free to contact: sebastian. kaminski@arup. com Shelter/NFI Sector Coordination Team: COORDINATOR Hani Chatila +880 187 274 8678 sheltercxb. coord@gmail. com CO-COORDINATOR Ratan Kumar Podder +880 173 031 8574 sheltercxb. coord 1@gmail. com www. humanitarianresponse. info/en/operations/bangladesh/shelter