The loss and devastation caused by Typhoon Haiyan in the Philippines has once again made salient the issue of wind and flood-proofing for buildings in regions vulnerable to such natural disasters.
Given the sheer force and magnitude of Typhoon Haiyan, which had peak wind speeds of more than 300 kilometres per hour, the question inevitably arises of whether it is possible, let alone practicable, for existing materials and engineering techniques to devise structures which are capable of withstanding such cataclysmic events.
Engineering and design experts concur that is indeed theoretically possible to construct buildings which can endure the onslaught of a natural disaster pitched at Typhoon Haiyan’s intensity. The premiums levied for the materials and methods required, however, may also render unfeasible the widespread adoption of such measures.
Tornado doors, designed for winds in excess of 480 kilometres per hour, are already on the market in North America. Reinforced glass capable of withstanding 300 kilometre per hour winds is also commercially available, while hurricane shutters can provide further protection against the possibility of heavy winds lobbing airborne debris through windows.
Reinforced concrete, strengthened via the passive embedding of rebar or other reinforcing materials during the setting process, can dramatically increase the strength of buildings – in particular their ability to resist tensile stresses and high impact force.
While reinforced concrete is necessary for the very construction of many modern buildings due to their heightened structural demands, an additional measure known as insulating concrete form (ICF) can be used in tandem with reinforced concrete to raise building strength via an ingenious system of formwork.
ICF involves fitting together modular units to produce the basic structure of buildings, in a manner akin to the Lego blocks so beloved by small children. The modules can be made from any one of a range of materials, including polystyrene foam and cement-bonded wood fiber.
Reinforced concrete is pumped into the modular units following the completion of the fitting process, conferring buildings with increased structural integrity compared to traditional framed walls. This technique also offers a number of benefits in other areas, including greater energy efficiency, acoustic absorbance and fire resistance.
Other structural measures can play a pivotal role in enhancing the disaster-resistance of buildings. Metal tie-down straps can be used to affix the roofing structure of a building to its very foundations, and a range of structural connectors can also be used to greatly diminish the damage caused to rooftops by uplift.
While all of these methods are currently on the market, and many have been in existence for decades, their high cost renders their usage prohibitive in most circumstances. This is especially the case in those tropical regions of the globe most susceptible to typhoons, which are currently dominated by low-income emerging economies.
Many experts say measures for extreme wind resistance are best reserved for emergency management facilities in vulnerable areas, as their exorbitant cost can be justified by their designated role as places of shelter and refuge during disasters.