I am a seismic engineer with Arup based in the...
Base isolation is seismic engineering’s equivalent of seatbelts in cars – and maybe more: it’s a lifesaver and possibly a property saver. That’s why I believe base isolation needs to be made a legal requirement for most new non high-rise buildings in areas at risk from earthquakes.
Base isolating a building is an engineering technique that places bearings between a building and the ground to reduce seismic vibrations. This minimises damage by significantly reducing the forces experienced during an earthquake.
The system is already used in countries like the US and Japan to protect historic buildings and vital infrastructure such as bridges and airports. The Space Shuttle Endeavour is protected by base isolation at the California Science Center, while Turkey’s Sahiba Gökçen International Airport is the largest seismically isolated building in the world. However, base isolation could, and should, be applied much more widely.
Base isolation is effective on short, stiff structures – most residential units around the world fall into this category. So if it was to be made compulsory in areas of seismic risk, the market would quickly develop to help drive down the cost of the systems and millions of people would benefit.
From a financial perspective, base isolation helps reduce rebuilding costs after earthquakes and minimises lifecycle cost. It also minimises the cost of damage to building contents. Plus, it could enable buildings to be used without interruption during a seismic event.
By not protecting buildings in this way, we risk paying a high price. I’ve seen the devastating human and economic impact of earthquakes first-hand in Pakistan and Haiti. Less developed countries may not have the expertise or resources to implement base isolation, but there’s no reason why richer seismically active countries such as China, Turkey and India shouldn’t adopt it.
What’s more, this isn’t just about reducing loss of life and devastation such as that caused by the Christchurch earthquake in 2011 or in Iran this week. Base isolation could eliminate much of the damage caused by smaller earthquakes, reducing the costs incurred and making homes and communities more resilient.
So why isn’t the engineering community calling for base isolation to be mandatory? I think one reason is that earthquake engineering is often perceived as a specialist design activity. As a result, it’s also perceived to add capital cost to projects without any consideration being given to the huge damage to property in an earthquake.
In many countries where it’s still an emerging discipline, civil and structural engineers are not routinely taught about structural dynamics and earthquake engineering. To me, that’s like going to medical school and not learning about antibiotics. I think that base isolation should become the new norm, just as cars come with seatbelts.
Engineers are the custodians of the built environment and we have a responsibility to make sure that the environment is healthy, robust and resilient. As part of this, we must have the courage to push for laws requiring all buildings in areas of seismic risk to be earthquake resistant. Making base isolation the norm through appropriate legislation will take us one step closer to having resilient homes, communities and cities.