The U.S. Geological Survey estimates there are about 1,000,000 earthquakes happening around the world each year, though majority of that number is too faint and can only be detected by seismometers. One million may seem a lot, but that’s inevitable considering that the earth’s crust rests on constantly moving masses of molten rock.
Seismic wallpaper by the Karlsruhe Institute of Technology
Making buildings earthquake-resistant hasn’t always been easy for earthquake engineers. Despite their best efforts to improve a building’s seismic performance—using base isolation, vibration control, and steel plate shear wall systems for instance—nothing is sturdy or pliant enough once nature decides to unleash its full fury.
Recently, researchers at the Karlsruhe Institute of Technology (KIT) in Karlsruhe, Germany have come up with an ingenious way to reinforce walls of a building, meant to supplement the abovementioned methods. The invention, called Sisma Calce (Earthquake Lime in Italian), is a seismic fabric made of glass fibers and elastic polypropylene fibers that can be applied on exterior walls using a special plaster.
The idea is that the seismic fabric holds the walls together during a short and moderate earthquake, unlike naked, unsupported walls that are more vulnerable to cracking and falling off. For occupants trying to flee a building during a quake, Sisma Calce can no doubt buy them some time, lessening the chances of falling debris that can hurt them and block their path.
With the new seismic fabric, retrofitting buildings, usually a costly, laborious process, can be made easier and less expensive. The low-cost solution is even perfect for poor and developing countries looking to reinforce and strengthen their existing buildings. Each year, fatalities in these countries can reach thousands because most old buildings aren’t properly equipped for earthquakes, even a moderate one that would have otherwise resulted in a mere crack in newer, sturdier structures. A simple retrofitting with seismic fabric can change this.
Sisma Calce is by no means a new invention. Fiber reinforced plastic (FRP) wraps for repairing and reinforcing structures was pioneered by Dr. Mo Ehsani of the University of Arizona as early as 1994, and now goes by the trademark of QuakeWrap. Sisma Calce inventors Lothar Stempniewski and Moritz Urban has a different attack however: by incorporating a wrap with four fiber directions, the resulting seismic fiber has remarkable stiffness and tensile strength that can withstand horizontal forces of an earthquake.
Last April, the KIT, in partnership with Bayer, also developed a seismic wallpaper which they called EQ-Top.
Right now, the goal is to launch Sisma Calce and make it available in the market. Italian construction material company Röfix has added the seismic fiber to its list of products.
For now, there might not be a way to fully earthquake-proof a building as we are always at the mercy of nature’s forces, but with the new seismic fabric making it at least earthquake-resistant just became a lot easier.
Sisma Calce Advantages
1. Lessens structural damage of walls during an earthquake
2. Lessens chance of fatal falling debris
3. Extends escape time for building occupants during an earthquake
4. Reinforcement to improve seismic performance of new buildings
5. Low-cost solution for retrofitting old buildings
6. Facilitates the repair of earthquake-damaged walls
