what is damping and why is it useful erthquake ressistant bulding?

Answer 1

daming is absorbing a shock
damping ratio is how fast a structure stop moving due to a blast or earth quake
dampers used in high rise buildings to reduce its natural frequensy which reduces the time needed to stop

Answer 2

Damping is a force in a system acting on a body that is proportional to the body's velocity. It is a component in dealing with system resonance, which is the matching of excitation frequency to the reactive frequency of a mechanical system.

Damping systems are used to dissipate the sensitivity of a structure to resonant frequency excitation. This is exactly why shocks are used in autos (in the case of a car, deflating resonance has the effect of keeping the tires in contact with the road the greatest amount of time, even though the car is hitting bumps).

Answer 3

Damping is the energy dissipation properties of a material or system under cyclic stress. Active damping and passive damping:

Active damping:
Active damping refers to energy dissipation from the system by external means, such as controlled actuator, etc.
Passive damping:
Passive damping refers to energy dissipation within the structure by add-on damping devices such as isolator, by structural joints and supports, or by structural member's internal damping.

Material damping and system damping:

Material damping:
Energy dissipation in a volume of macro-continuous media.
System damping:
Energy dissipation in the total structure. in addition to damping due to materials, it also includes energy dissipation effects of joints, fasteners, and interfaces.

Damping Measurement:

There are many methods for measuring the damping of a vibtation system. Logarithmic decrement method and bandwidth meathod are introduced here.

Logarithmic decrement method is used to measure damping in time domain. In this method, the free vibration displacement amplitude history of a system to an impulse is measured and recorded. A typical free decay curve is shown as below.Logarithmic decrement is the natural logarithmic value of the ratio of two adjacent peak values of displacement in free decay vibration.

Damping in machine tools basically is derived from two sources--material damping and interfacial slip damping. Material damping is the damping inherent in the materials of which the machine is constructed. The magnitude of material damping is small comparing to the total damping in machine tools. A typical damping ratio value for material damping in machine tools is 0.003. It accounts for approximately 10% of the total damping.

The interfacial damping results from the contacting surfaces at bolted joints and sliding joints. This type of damping accounts for approximately 90% of the total damping. Among the two types of joints, sliding joints contribute most of the damping. Welded joints usually provide very small damping which may be negleted when considering damping in joints.

Answer 4

It is basically like a shock absorber in a car, you use fluid pressure to counteract the force of the earthquakes vibration.