One of the key factors to minimizing damage caused by tsunamis is to build structures that can withstand the damage of such storms. In light of past damage assessed from tsunamis and related storms, engineers from around the world have compiled several different lists of basic requirements in a "tsunami-proof" building.
General lessons include:
When designing our "perfect building," we will be elevating the structure above a solid but open foundation to help alleviate the pressures from built up levels of water. Many of the buildings in the Sri Lanka tsunami had their back walls blown out due to the growing pressure from the water as it filled the buildings (Grose). Many of the building foundations also had scarring from water that funneled beneath them, accelerating from the impact. Also, in foundations of sand, whirlpools formed at building corners, which scarred and undermined the foundations even more (Minor). In addition, multi-level buildings allowed the people inside to reach heights above the wave crests to reduce casualties (Grose).
When comparing building materials, it was found that reinforced concrete structures were more likely to survive the wave forces brought by a tsunami, as compared to masonry and wood structures, which did not fare well at all (Natural Hazards). However, even brick buildings, when properly reinforced, have been found to be effective in storm situations as well. Our perfect building would be ideally made of a material, or hybrid material, that is as effective at resisting wave forces as reinforced concrete, but less costly and more readily available in areas at high risk for tsunamis.
Orientation is Key
It was found that walls that faced the ocean, allowing for a perpendicular impact from the tsunami waves, sustained a considerably higher amount of damage than walls orientated in the direction of water flow (Grose). Orientation is also important due to the massive amounts of debris that can be found in the flow resulting from tsunamis. In fact, more tsunami victims are injured or die from debris pushed along by the tsunami waves than by any other secondary cause (Dalrymple). The orientation of certain buildings with respect to the flow of coastal waters, and with respect to other buildings in the city, can minimize the debris that gets loose in a storm and has the potential to harm or kills humans (Grose).
Gone With the Wind
Research has found that once windows or doors are damaged in a building, it sets off a chain reaction that escalates the damage done to the structure. The immediate result of a failed door or window is an increase in internal pressure, which in turn causes an overall roof uplift pressure (Minor). This chain reaction continues, with the removal of the roof sheathing, wind and rain entering the building, and the progressive failure of the building frame itself. This compounded exposure greatly increases the cost of damage, and makes recovery from such natural disasters much more difficult (Minor).
So...What do we do?
Our team plans on creating the optimal, "utopian" city that lies at risk of a tsunami attack. To fulfill this dream, we must design the city and all its individual components to serve the most effective purpose against the forces of a tsunami. In the past, another MIT team came up with a protocol design for cost efficient homes designed to help the people of Sri Lanka live in tsunami-resistant homes (Brehm). I will be taking this design pattern and modeling my own after it, making any necessary changes when accounting for local materials, differences in cost, or any other necessary design changes.
The protocol design is a wood or bamboo home solidified by 4 concrete and rebar columns, each about 3meters wide. Each costing at around $1200, these 400 square feet homes would also be built on concrete or wooden blocks around 1 to 2 feet above the ground in order to allow high waters to pass under the home instead of knocking it over. In addition to this "open foundation" design, the floor plan of the house itself is also open floor, once again allowing powerful ocean waves to pass through the home and not knock it flat.
Page by: Danbee Kim
Link: Annotated Bibliography