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Seismic Vibration Control
In earthquake engineering, vibration control is a set of technical means aimed to mitigate seismic impacts in building and non-building structures. All seismic vibration control devices may be classified as ''passive'', ''active'' or ''hybrid'' where: * ''passive control devices'' have no feedback capability between them, structural elements and the ground; * ''active control devices'' incorporate real-time recording instrumentation on the ground integrated with earthquake input processing equipment and actuators within the structure; * ''hybrid control devices'' have combined features of active and passive control systems. When ground seismic waves reach up and start to penetrate a base of a building, their energy flow density, due to reflections, reduces dramatically: usually, up to 90%. However, the remaining portions of the incident waves during a major earthquake still bear a huge devastating potential. After the seismic waves enter a superstructure, there is a number ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-rise Building
A tower block, high-rise, apartment tower, residential tower, apartment block, block of flats, or office tower is a tall building, as opposed to a low-rise building and is defined differently in terms of height depending on the jurisdiction. It is used as a residential or office building, or has other functions, including hotel, retail, or with multiple purposes combined. Residential high-rise buildings are also known in some varieties of English, such as British English, as tower blocks and may be referred to as MDUs, standing for multi-dwelling units. A very tall high-rise building is referred to as a skyscraper. High-rise buildings became possible to construct with the invention of the elevator (lift) and with less expensive, more abundant building materials. The materials used for the structural system of high-rise buildings are reinforced concrete and steel. Most North American–style skyscrapers have a steel frame, while residential blocks are usually constructed o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vibration Isolation
''Vibration isolation'' is the prevention of transmission of vibration from one component of a system to others parts of the same system, as in Building, buildings or mechanical systems. Vibration is undesirable in many domains, primarily engineered systems and habitable spaces, and methods have been developed to prevent the transfer of vibration to such systems. Vibrations propagate via mechanical waves and certain mechanical linkages conduct vibrations more efficiently than others. Passive vibration isolation makes use of materials and mechanical linkages that absorb and damp these mechanical waves. Active vibration isolation involves sensors and actuators that produce disruptive interference that cancels-out incoming vibration. Passive isolation "Passive vibration isolation" refers to vibration isolation or mitigation of vibrations by passive techniques such as rubber pads or mechanical springs, as opposed to "active vibration isolation" or "electronic force cancellation" employi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metallic Roller Bearing
In earthquake engineering, a metallic roller bearing is a base isolation device which is intended for protection of various building and non-building structures against potentially damaging lateral impacts of strong earthquakes. This bearing support may be adapted, with certain precautions, as a seismic isolator to skyscrapers and buildings on soft ground. Metallic roller bearings are employed by a housing complex (17 stories) in Tokyo, Japan Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most .... See also * Earthquake-resistant structures * Elevated building foundation References Earthquake engineering Seismic vibration control {{architecture-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cushioning
Package cushioning is used to protect items during shipment. Vibration and impact shock during shipment and loading/unloading are controlled by cushioning to reduce the chance of product damage. Cushioning is usually inside a shipping container such as a corrugated box. It is designed to absorb shock by crushing and deforming, and to dampen vibration, rather than transmitting the shock and vibration to the protected item. Depending on the specific situation, package cushioning is often between thick. Internal packaging materials are also used for functions other than cushioning, such as to immobilize the products in the box and lock them in place, or to fill a void. Design factors When designing packaging the choice of cushioning depends on many factors, including but not limited to: * effective protection of product from shock and vibration * resilience (whether it performs for multiple impacts) * resistance to creep – cushion deformation under static load * material cos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-vibration Compound
An anti-vibration compound is a temperature-resistant mixture of a liquid with fine particles, which is used to reduce oscillations in calender rolls and to dampen vibrations in fabricated structures like machine beds and housings. Use Vibration may limit the performance of a calender or paper machine. It can have numerous sources such as bulk variations in the sheet, bearing problems, or misalignment of the driveshaft. Vibration manifests itself as a high frequency periodic movement of the roll body with an amplitude from less than one to several μm. When anti-vibration compound is introduced to the center bores of the rolls, vibration is transferred from the solid roll structure to the incompressible fluid component of the anti-vibration compound. Its solid particles are less mobile due to their inertia. Thus the fluid is forced to oscillate around the solid components. The flow energy is absorbed by micro eddies by which the vibration is damped. The benefits are a smoother ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Vibration Control
Active vibration control is the active application of force in an equal and opposite fashion to the forces imposed by external vibration. With this application, a precision industrial process can be maintained on a platform essentially vibration-free. Many precision industrial processes cannot take place if the machinery is being affected by vibration. For example, the production of semiconductor Wafer (electronics), wafers requires that the machines used for the photolithography steps be used in an essentially vibration-free environment or the sub-micrometre features will be blurred. Active vibration control is now also commercially available for reducing vibration in helicopters, offering better comfort with less weight than traditional passive technologies. In the past, passive techniques were used. These include traditional vibration Damping ratio, dampers, shock absorbers, and base isolation. The typical active vibration control system uses several components: * A massive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanical Snubber
A mechanical snubber is a mechanical device designed to protect components from excess shock or sway caused by seismic disturbances or other transient forces. During normal operating conditions, the snubber allows for movement in tension and compression. When an impulse event occurs, the snubber becomes activated and acts as a restraint device. The device becomes rigid, absorbs the dynamic energy, and transfers it to the supporting structure. The image at right shows an isometric view of one style of mechanical snubber. When a disturbance occurs that exceeds the acceleration threshold of the snubber, the ball screw and drum produce angular momentum to the inertia mass. The inertial resistance of the mass engages the resilient capstan to tighten around a hardened mandrel, which is part of the structural tube. This, in turn, causes restraining force against the rotation of the ball screw. During standard operation, the associated acceleration is far below the threshold limit of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snubber
A snubber is a device used to suppress ("wiktionary:snub, snub") a phenomenon such as voltage transients in electronics, electrical systems, pressure transients in fluid systems (caused by for example water hammer) or excess force or rapid movement in mechanics, mechanical systems. Electrical systems Snubbers are frequently used in electrical systems with an electromagnetic induction, inductive load where the sudden interruption of electric current, current flow leads to a large counter-electromotive force: a rise in voltage across the current switching device that opposes the change in current, in accordance with Faraday's law of induction, Faraday's law. This transient can be a source of electromagnetic interference (EMI) in other circuits. Additionally, if the voltage generated across the device is beyond what the device is intended to tolerate, it may damage or destroy it. The snubber provides a short-term alternative current path around the current switching device so that th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P-Delta Effect
In structural engineering, the P-Δ or P-delta effect refers to the abrupt changes in ground shear, overturning moment, and/or the axial force distribution at the base of a sufficiently tall structure or structural component when it is subject to a critical lateral displacement. A distinction can be made between P-delta effects on a multi-tiered building, written as P-Δ, and the effects on members deflecting within a tier, written as P-δ. P-delta is a second-order effect on a structure which is loaded laterally. One first-order effect is the initial deflection of the structure in reaction to the lateral load. The magnitude of the P-delta effect depends on the magnitude of this initial deflection. P-delta is a moment found by multiplying the force due to the weight of the structure and applied axial load, ''P'', by the first-order deflection, ''Δ'' or ''δ''. NUMERICAL EXAMPLE OF P DELTA EFFECT ON A CALCULATOR You have a 1 meter tall rigid vertical rod that rotates on a hin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moat
A moat is a deep, broad ditch dug around a castle, fortification, building, or town, historically to provide it with a preliminary line of defence. Moats can be dry or filled with water. In some places, moats evolved into more extensive water defences, including natural or artificial lakes, dams and sluices. In older fortifications, such as hillforts, they are usually referred to simply as ditches, although the function is similar. In later periods, moats or water defences may be largely ornamental. They could also act as a sewer. Historical use Ancient Some of the earliest evidence of moats has been uncovered around ancient Egyptian fortresses. One example is at Buhen, a settlement excavated in Nubia. Other evidence of ancient moats is found in the ruins of Babylon, and in reliefs from ancient Egypt, Assyria, and other cultures in the region. Evidence of early moats around settlements has been discovered in many archaeological sites throughout Southeast Asia, including ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
