Earthquake engineering, or seismic retrofitting, is the construction or modification of buildings to make them resistant to seismic activity, soil failure, and ground motion.
Over 5,000 deaths are recorded each year due to earthquakes. This is just one part of the devastation that can be wrought – there is also an accompanying loss of livelihood, infrastructure, and property.
Architects are always developing new methods to earthquake-proof buildings. Although it is not possible to build a structure entirely safe from earthquakes, there are some mainstays in steps we can take to ensure a lower risk.
The most common structures requiring seismic retrofitting are bridges, dams, road viaducts, towers, unreinforced masonry and insufficiently enforced concrete structures.
Here are some methods in creating earthquake-resistant architecture.
Steel Plate Walls
Steel plate shear walls (SPSW) are among the most popular earthquake-resistant materials.
These are used to add integrity in a cost-effective manner. They cheaper and faster to create than concrete walls, and reinforce walls while ensuring the walls are made more compact.
Like steel plate walls, this is an affordable building construction system.
It was devised in the Philippines. Multiple “boxes” are arranged to make one building and each box constitutes four micro-portal frames that are resistant to quakes and even harsh winds.
These unique homes can be relocated if required, since they are portable.
There are various ways to reinforce a structure, including:
Constructing a structure so it moves along with its foundation
Suspending a structure above its foundations
Foundations reinforced with steel
It is vital to minimize the weight of a building on its foundation.
Seismic Shock Absorbers
Shock absorbers or dampeners, as their names suggest, protect buildings against earthquake shock.
This seismic retrofitting creation sprang from Japan.
A cable curtain is a large “curtain” of carbon fiber and thermo plastic cables that provide protection to a building. While fibers are lighter than metal, they are about as strong as iron.
Should an earthquake hit, these cables will respond by stretching, counteracting the shaking and providing stability to the building.
By constructing a building in accordance with the building codes based on the seismic history of a region, the extent of damage due to earthquakes can be greatly reduced.
Two successful examples of earthquake-resistant architecture include:
In October 1989, a high-magnitude earthquake hit central California. A 49-story office building shook for more than a minute, but no one was seriously injured, and the Transamerica Pyramid was not damaged.
In 1994, the Northridge earthquake cracked the surface pavement on a slope of the Los Angeles Dam. Overall, there was little damage to the dam.
Complete probabilistic analysis and design approach
Performance-based design codes
Multiple annual probability hazard maps
Structural systems and devices using non-traditional civil engineering materials and techniques
If you have any queries about seismic retrofitting, please contact us!
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