Skyscrapers are amazing! Architectural defeats. Wonders of the world. How are they able to withstand even the strongest of winds and earthquakes?
Today, engineers rely on damping systems to counteract nature's forces. There are many types of damping systems that engineers can now use for structures, automobiles, and even tennis rackets! This site focuses on damping systems in structures, mainly architectural variations of the tuned mass damper.
How Tuned Mass Dampers Work
A tuned mass damper (TMD) consists of a mass (m), a spring (k), and a damping device (c), which dissipates the energy created by the motion of the mass (usually in a form of heat). In this figure, M is the structure to which the damper would be attached.
From the laws of physics, we know that F = ma and a = F/m. This means that when an external force is applied to a system, such as wind pushing on a skyscraper, there has to be an accleration. Consequently, the people in the skyscraper would feel this acceleration. In order to make the occupants of the building feel more comfortable, tuned mass dampers are placed in structures where the horizontal deflections from the wind's force are felt the greatest, effectively making the building stand relatively still.
When the building begins to oscillate or sway,
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If their frequencies were significantly different, the TMD would create pushes that were out of sync with the pushes from the wind, and the building's motion would still be uncomfortable for the occupants. If their amplitudes were significantly different, the TMD would, for example, create pushes that were in sync with the pushes from the wind but not quite the same size and the building would still experience too much
Cappa, John, Sean Holman, and Ken Brubaker. "Automobiles- Springs and Suspension." Fourwheeler. NC WiseOwl, May 2012. Web. 17 Feb. 2014. .
...ad to use cantilevers which were beams anchored at only one end. These beams carry the load to support where the force is concentrated by a moment and shear stress. Fallingwater indeed was a revolutionary structure due to the fact that it had many unique aspects. From how famous the house became, Fallingwater was featured on the cover of Time magazine, in 1938.
Stringent seismic criteria related to construction in the San Diego area made it difficult for Kahn's structural engineer to convince local building officials, who wanted him to use steel frame, that concrete, Vierendeel truss system would have the required flexibility. They agreed only after a 400 page report of undoubtedly integrated deflection computations that shows how post-tensioned columns would provide the main resistance to lateral seismic forces. These columns absorb both dead and live load compression plus vertical post-tensioning forces. They were also designed to maintain zero tension if subjected to lateral movements by earthquake. The trusses are 9 ft deep, spaced 20 ft on center and have a clear span of 65 ft (diagram 2). He made use of the 9 ft high resultant space as service area, allowing pipe chases to be dropped to the 65x 245 ft floor below with more latitude than before.
Suspension system is used to absorb shocks and jerks from road or rough terrain. Suspension allows wheel to move independently to the body. Suspension components, wheel rims and brake components are known as un-sprung masses, which is important for better ride quality as well as it is meant to reduce the total vehicle weight. Comfort can be achieved by isolating the riders from road disturbances like bumps or potholes and Control is achieved by keeping car body from rolling and pitching, and maintaining good contact between road to tyre.
We will now look at the physics of a trebuchet. “The trebuchet uses many different physics applications, we will look at a few of them. Basically a trebuchet is a fulcrum.
1.0 Terms of Reference This formal report has been written for students, government agencies and engineering development companies. Forecasting it to be completed before the 18th May 2015, It serves the purpose of assisting and providing insight to people conducting researches pertaining to this specific topic, whether it is to understand the previous errors made in construction or to improve static structural building standards based on history failures. As acknowledged by the writer, this chosen topic is one of which contains ample debates ranging from a diverse band of perceptions. Hence, the scope of this report will purely cover how the World Trade Centre collapsed on September the 11th 2001 from scientific; mathematical, structural and
The average wind on the entire site is approximately 9m/s. Wind speeds of 7.5m/s are deemed economically viable. The wind speed can vary dramatically onsite. The wind speed was very low at 3m/s when we were there and we were told on our site visit that there have being wind speeds up to 50m/s experienced on the site. To prevent any damage the turbines cut out at a certain wind speed. This is typically 25m/s for the turbines on site.
F = ma : where F is force; m is the mass of the body; and a is the acceleration due to that particular force
Vehicle suspension is the system of springs and dampers that controls vertical oscillations of the vehicle, determining ride comfort and operating safety. With the technology available today, there are three different functions that can be accomplished with adjustable, electronically controlled suspension.
where J is the moment of inertia of the armature–flapper assembly, Br is the damping coefficient for rotation of the armature–flapper assembly, Tnozzle is the torque produced by the net flow force, m is the mass of the armature–flapper assembly, and Bt is the damping coefficient for translation of the armature–flapper assembly.
Kineticsnoise.com. 2013. Spring Lift Slab Concrete Floating Floor System | Model LSM. [online] Available at: http://www.kineticsnoise.com/arch/lsm.html [Accessed: 25 Nov 2013].
Shock absorbers, otherwise known as dampeners, reduce the vertical movement of the car as it drives down a rough surface. Without this piece of the suspension system, your car would rock and sway back and forth viciously. “It would be a traveling deathtrap. Or at least it would be a traveling deathtrap until the incessant vibration caused it to fall apart,” says Longhurst. Shock absorbers have two main functions. They both absorb any over-average bumps in the road, as I mentioned above, and secondly they keep your wheels on the ground as you drive. (Longhurst)
Two or more forces acting on a body in different directions may balance, producing a state of equilibrium. For example, the downward force of gravity (see gravitation) on a person weighing 200 lb (91 km) when standing on the ground is balanced by an equivalent upward force exerted by the earth on the person's feet. If the person were to fall into a deep hole, then the upward force would no longer be acting and the unbalanced force of gravity would accelerate the person downward. If a body is not completely rigid, then force acting on it may change its size or shape. Scientists study the strength of materials to anticipate how a given material may behave under the influence of various types of force.
Earthquakes are vibrations felt at the surface of the earth which are caused by disturbances of the energy in the earth's interior. These vibrations are known as seismic waves. (Skinner Robinson McVerry 1) There are different type sof seisimc waves such as Primary (P) waves, whcih travel the fastest, Secondary (S) waves which cause the earth to vibrate vertically, Surface (L) waves. P and S waves are "affected by changes in the density and the rigidity of the materials through which they pass." (Columbia Encyclopedia) Earthquakes vary in their intensity and duration. Often times they are strong enough to cause massive destriction. Tall buildings often suffer as a result of these natural disasters. In recent years this has become a larger and larger threat with both the number of large buildings, and their number of occupants increasing. In an effort to try to minimize the damage caused by earthquakes many some engineers focus primarily on designing and constructing earthquake resistant buildings. Earthquake engineers have gathered much of their information from analyzing past earthquakes, and learning which buildings can and can't withstand the tremors. The goals of these engineers is to design buildings that can withstand moderate earthquakes and obtain minimal damage, and that the buildings will not collapse lowering the probability of human deaths.
Taher, R. (2011). General recommendations for improved building practices in earthquake and hurricane prone areas. San Francisco, CA: Architecture for Humanity Retrieved from