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Quake-Proof buildings. Maher Alhalabi. Why do we need a quake-proof buildings ? Are we able to construct such buildings ?. Techniques used to construct a quake-proof buildings Isolated Base technology Diagonal Bracing Passive Damping. Isolated Base technology
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Quake-Proof buildings Maher Alhalabi
Why do we need a quake-proof buildings ? • Are we able to construct such buildings ?
Techniques used to construct a quake-proof buildings • Isolated Base technology • Diagonal Bracing • Passive Damping
Isolated Base technology In this approach, the building or structure is decoupled from the horizontal components of the earthquake ground motion , by interposing a layer with low horizontal stiffness between the structure and the foundation. Carbon and other materials are mixed in the rubber to produce High Strength Rubber bearings
DiagonalBracing This feature of modern buildings is the use of cross-supports in between the frame supports, or between the corners of the frame. This helps stabilize the frame against sideways forces from earthquakes since it helps resist shearing forces that come from the swaying motion of a shaken building .
Single Bracing frame : If a single diagonal is used, it must be able to resist tension (stretching) and compression (squashing) caused by sideways forces in both directions on a frame. Cross bracing frames : If two diagonals are used, in the form of cross-bracing, they only need to resist tension. This is because one brace is in tension for the sideways force in one direction on the frame, while the other brace is in tension when the force is reversed. Knee Bracing K-Bracing V-Bracing Inverted-V
Passive Damping When a base-isolated building is undergoing an earthquake wave motion , the base isolator can stabilize the displacement , it will not affect the energy accompanied with the seismic wave . Dampers play this role of reducing this energy by converting the energy of motion of a moving object into a different form of energy, which is heat. It takes energy out of any movement .
There are three main categories of passive damping : 1- Distributed damping : It needs to be specified at a building’s concept stage and involves carefully placing dampers, typically visco-elastic or hydraulic devices 2- Liquid damping : In this approach tanks are integrated into a space at the top of a building and filled with a precise amount of water. As the building sways, the water in the tank sloshes back and forth and a grid or paddles placed in the tank move against the water, generating turbulence, which heats up the water. In this way, the energy from the movement of the building is turned into heat
3- Tuned mass damper : This damper uses a giant pendulum placed at the top of the building. It has of a platform attached to cables which hang down from a support above. Heavy steel plates are laid onto this platform to form a swinging mass .The mass sways out of phase with the building’s natural vibration in order to dampen its movement in such a way the rate of sway of the pendulum match the rate of sway of the building to artificially create large movements where normally a building would only have small movements. This will push the shock absorber back and forth and convert energy of motion into energy of heat.
Economical Damages due to an earthquake Direct economic damage : Which can involve facilities damage, including building, household assets, business assets, and business stock, and lifeline damage, including water supply and sewage pipes, electricity, gas and communications . Indirect economic damage : Which can involve loss due to production and service stoppages in the manufacturing, construction, electricity, gas and water, wholesale and retail, transportation and communications real estate, and service industries .
Question : List three real life examples of buildings that have implemented some or all of the quake-proof technologies , and how these technologies might have affected the survival of these buildings .
References : 1- Base Isolation: Origins and Development,” EERC News, Vol. 12, No. 1, January 1991 2- Wikipedia – Earthquake proof 3- When the big one strikes again paper - Charles A. Kircher,a) M.EERI, Hope A. Seligson,b) M.EERI, Jawhar Bouabidc) M.EERI, and Guy C. Morrowd) M.EERI 4- United States – Department of Energy 5- Earthquake research engineering center – University of California Berkeley 6- IDEERS – Bristol University 7- USGS website 8- BD website , The architect’s website . 9- Coupled building control paper – University of Washington . 10 – “How to estimate the Economic Loss? “ paper – Harumi Yashiro, Fumiaki Yoshimura, Fujiko Tatsumi , Asian Disaster Reduction Center