12-02-2012, 06:14 PM
PLZSEND ME SOME INFORMATION ABOUT ADVANCED EARTHQUAKE RESISTANT STRUCTURES
12-02-2012, 06:14 PM
PLZSEND ME SOME INFORMATION ABOUT ADVANCED EARTHQUAKE RESISTANT STRUCTURES
13-02-2012, 01:49 PM
to get information about the topic earthquake resistant techniques full report ,ppt and related topic refer the link bellow
https://seminarproject.net/Thread-advanc...ant-design
15-02-2012, 01:41 PM
internet access via cable tv network full documentation
09-03-2012, 03:48 PM
PLZSEND ME SOME INFORMATION ABOUT ADVANCED EARTHQUAKE RESISTANT STRUCTURES
11-10-2012, 12:48 PM
Advanced Earthquake Resistant Design Techniques Introduction The conventional approach to earthquake resistant design of buildings depends upon providing the building with strength, stiffness and inelastic deformation capacity which are great enough to withstand a given level of earthquake–generated force. This is generally accomplished through the selection of an appropriate structural configuration and the careful detailing of structural members, such as beams and columns, and the connections between them. In contrast, we can say that the basic approach underlying more advanced techniques for earthquake resistance is not to strengthen the building, but to reduce the earthquake–generated forces acting upon it. Among the most important advanced techniques of earthquake resistant design and construction are base isolation and energy dissipation devices. Base Isolation It is easiest to see this principle at work by referring directly to the most widely used of these advanced techniques, which is known as base isolation. A base isolated structure is supported by a series of bearing pads which are placed between the building and the building's foundation.(See Figure 1) A variety of different types of base isolation bearing pads have now been developed. For our example, we'll discuss lead–rubber bearings. These are among the frequently–used types of base isolation bearings. (See Figure 2) A lead–rubber bearing is made from layers of rubber sandwiched together with layers of steel. In the middle of the bearing is a solid lead "plug." On top and bottom, the bearing is fitted with steel plates which are used to attach the bearing to the building and foundation. The bearing is very stiff and strong in the vertical direction, but flexible in the horizontal direction. Response of Base Isolated Building By contrast, even though it too is displacing, the base–isolated building retains its original, rectangular shape. It is the lead–rubber bearings supporting the building that are deformed. The base–isolated building itself escapes the deformation and damage—which implies that the inertial forces acting on the base–isolated building have been reduced. Experiments and observations of base–isolated buildings in earthquakes have been shown to reduce building accelerations to as little as 1/4 of the acceleration of comparable fixed–base buildings, which each building undergoes as a percentage of gravity. As we noted above, inertial forces increase, and decrease, proportionally as acceleration increases or decreases. Acceleration is decreased because the base isolation system lengthens a building's period of vibration, the time it takes for the building to rock back and forth and then back again. And in general, structures with longer periods of vibration tend to reduce acceleration, while those with shorter periods tend to increase or amplify acceleration. Finally, since they are highly elastic, the rubber isolation bearings don't suffer any damage. But what about that lead plug in the middle of our example bearing? It experiences the same deformation as the rubber. However, it also generates heat as it does so. Energy Dissipation Devices The second of the major new techniques for improving the earthquake resistance of buildings also relies upon damping and energy dissipation, but it greatly extends the damping and energy dissipation provided by lead–rubber bearings. As we've said, a certain amount of vibration energy is transferred to the building by earthquake ground motion. Buildings themselves do possess an inherent ability to dissipate, or damp, this energy. However, the capacity of buildings to dissipate energy before they begin to suffer deformation and damage is quite limited. The building will dissipate energy either by undergoing large scale movement or sustaining increased internal strains in elements such as the building's columns and beams. Both of these eventually result in varying degrees of damage. So, by equipping a building with additional devices which have high damping capacity, we can greatly decrease the seismic energy entering the building, and thus decrease building damage. Fluid Viscous Dampers Once again, to try to illustrate some of the general principles of damping devices, we'll look more closely at one particular type of damping device, the Fluid Viscous Damper, which is one variety of viscous damper that has been widely utilized and has proven to be very effective in a wide range of applications. The article, titled Application of Fluid Viscous Dampers to Earthquake Resistant Design, describes the basic characteristics of fluid viscous dampers, the process of developing and testing them, and the installation of fluid viscous dampers in an actual building to make it more earthquake resistant. |
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