Could this new anti-earthquake technology protect cities from destruction?

The Marina District of San Francisco in October 1989, after it was hit by an earthquake measuring 7.1 on the richter scale. Image: Getty.

Protecting cities from earthquakes is still a grand challenge that needs addressing, as recent disasters in Nepal, Japan, Haiti, and Chile show. Significant progress has been made in understanding seismic activity and in developing building technology – but we still don’t have a satisfactory way of protecting buildings on a large scale.

For new buildings, anti-seismic technology is today considered quite advanced, and it is possible to build individual structures that can withstand the vast majority of recorded earthquakes. Devices such as isolation systems and dampers, which are designed to reduce the vibrations – and, as a consequence, the damage – induced by earthquakes, are successfully being employed in the design of new buildings.

But large numbers of buildings exist in earthquake zones that don’t have built-in protection. That's particularly true in developing countries where replacing them or introducing stricter – and more expensive – building codes aren’t seen as an option. More than 130,000 houses were destroyed by the earthquake in Nepal in April 2015.

What’s more, these technologies are rarely used for protecting existing buildings, as they generally require substantial alteration of the original structure. In the case of heritage buildings, critical facilities or urban housing, especially in developing countries, traditional localised solutions might be impractical.

This means there is a need for alternative solutions that protect multiple existing buildings without altering them using a single device. At the University of Brighton, we have designed a new vibrating barrier (ViBa) to reduce the vibrations of nearby structures caused by an earthquake’s ground waves. The device would be buried in the soil and detached from surrounding buildings, and should be able to absorb a significant portion of the dynamic energy arising from the ground motion with a consequent reduction of seismic response of between 40 and 80% per cent.

In need of protection. Image: Narendra Shrestha/EPA.

The idea behind this technology was to look at buildings as an integral part of a city model, which also includes the soil underneath them and the interaction between each element, rather than as independent structures. Each ViBa can be designed to protect one or more buildings from an earthquake; but also it forms part of a network of devices placed at strategic locations in order to protect entire cities.

The ViBa itself is essentially a box containing a solid central mass held in place by springs. These allow the mass to move back and forth and absorb the vibrations created by seismic waves. The entire structure is connected to the foundations of buildings through the soil to absorb vibrations from them. The box’s exact position underground would depend on how deep the surrounding foundations went; it could even be placed on the surface.

As the ViBa is designed to reduce all vibrations in the soil, it could also be used to insulate buildings against ground waves from human activities such as road traffic, high-speed trains, large machinery, rock drilling and blasting. In this way, the technology would be able to absorb a larger quantity of energy than traditional measures used to insulate railways such as trenches or buried sheet-pile walls.

Starting construction

The problem with the ViBa is its size – it would need to be at least 50 per cent of the mass of the average building it was protecting – and how much money it would cost to build and install as a result. So compared to current technologies to protect single buildings it would likely come with a much higher price tag. But as the ViBa can be designed to reduce the vibrations of more than one building, or for buildings of historical importance for which current technologies are impractical, it can still be considered as a viable solution.

So far we have only modelled how the ViBa would work, using computers and prototypes in the lab. To be deployed in the real world we would need to do a lot more experimenting to understand exactly how it would work, and to make sure it didn’t produce any damaging side-effects on the surrounding buildings. We would also need to work with industry to work out how to build and install it in the most cost-effective way.

But our latest research suggests the ViBa is a viable alternative strategy for protecting buildings from earthquakes. In the long term, it could lead to safer cities that are better equipped to deal with disasters and ultimately save lives. The Conversation

Pierfrancesco Cacciola is assistant head of the School of Environment and Technology at the University of Brighton.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

Barnet council has decided a name for its new mainline station. Exciting!

Artist's impression of the new Brent Cross. Image: Hammerson.

I’ve ranted before about the horror of naming stations after the lines that they’re served by (screw you, City Thameslink). So, keeping things in perspective as ever, I’ve been quietly dreading the opening of the proposed new station in north London which has been going by the name of Brent Cross Thameslink.

I’ve been cheered, then, by the news that station wouldn’t be called that at all, but will instead go by the much better name Brent Cross West. It’s hardly the cancellation of Brexit, I’ll grant, but in 2017 I’ll take my relief wherever I can find it.

Some background on this. When the Brent Cross shopping centre opened besides the A406 North Circular Road in 1976, it was only the third large shopping mall to arrive in Britain, and the first in London. (The Elephant & Castle one was earlier, but smaller.) Four decades later, though, it’s decidedly titchy compared to newer, shinier malls such as those thrown up by Westfield – so for some years now, its owners, Hammerson, have wanted to extend the place.

That, through the vagaries of the planning process, got folded into a much bigger regeneration scheme, known as Brent Cross Cricklewood (because, basically, it extends that far). A new bigger shopping centre will be connected, via a green bridge over the A406, to another site to the south. There you’ll find a whole new town centre, 200 more shops, four parks, 4m square feet of offices space and 7,500 homes.

This is all obviously tremendously exciting, if you’re into shops and homes and offices and not into depressing, car-based industrial wastelands, which is what the area largely consists of at the moment.

The Brent Cross site. Image: Google.

One element of the new development is the new station, which’ll sit between Hendon and Cricklewood on the Thameslink route. New stations are almost as exciting as new shops/homes/offices, so on balance I'm pro.

What I’ve not been pro is the name. For a long time, the proposed station has been colloquially referred to as Brent Cross Thameslink, which annoys me for two reasons:

1) Route names make rubbish modifiers because what if the route name changes? And:

2) It’s confusing, because it’s nearly a mile from Brent Cross tube station. West Hampstead Thameslink (euch), by contrast, is right next to West Hampstead tube.

Various other names have been proposed for the station. In one newsletter, it was Brent Cross Parkway; on Wikipedia, it’s currently Brent Cross South, apparently through confusion about the name of the new town centre development.

This week, though, Barnet council quietly confirmed it’d be Brent Cross West:

Whilst the marketing and branding of BXS needs to be developed further, all parties agree that the station name should build upon the Brent Cross identity already established. Given the station is located to the west of Brent Cross, it is considered that the station should be named Brent Cross West. Network Rail have confirmed that this name is acceptable for operational purposes. Consequently, the Committee is asked to approve that the new station be named Brent Cross West.

Where the new station will appear on the map, marked by a silly red arrow. Image: TfL.

That will introduce another irritating anomaly to the map, giving the impression that the existing Brent Cross station is somehow more central than the new one, when in fact they’re either side of the development. And so:

Consideration has also been given as to whether to pursue a name change for the tube station from “Brent Cross” to “Brent Cross East”.

Which would sort of make sense, wouldn’t it? But alas:

However owing to the very high cost of changing maps and signage London-wide this is not currently being pursued.

This is probably for the best. Only a handful of tube stations have been renamed since 1950: the last was Shepherd’s Bush Market, which was until 2008 was simply Shepherd's Bush, despite being quite a long way from the Shepherd's Bush station on the Central line. That, to me, suggests that one of the two Bethnal Green stations might be a more plausible candidate for an early rename.


At any rate: it seems unlikely that TfL will be renaming its Brent Cross station to encourage more people to use the new national rail one any time soon. But at least it won’t be Brent Cross Thameslink.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and also has a Facebook page now for some reason. 

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