Impact of vibration and noise on people
People have created various facilities according to their purposes and uses. On the surface of the earth where these are located, waves due to the movement of underground magma and the crust are transmitted, causing pulsation and intermittent dead seismic motion. In addition, vibrations due to roads/traffic, industrial machinery, wind, waves, etc. are transmitted while being attenuated according to the structure and distance of the ground/building, creating an environment with constant weak vibrations (always slight vibration). ..
- Control targets of vibration control
- Houses (detached house, middle low-rise/high-rise house)
- General architecture (government buildings, banks, hotels, department stores, offices)
- Schools (nursery school, elementary and junior high school, library)
- Hospitals (hospital architecture, hospital rooms, operating rooms, examination rooms)
- Theaters (cinema, music hall, art museum, museum)
- Research facilities (university/research institute, research/development/experiment)
- Factories (heavy industry, light industry, production/processing/inspection)
- Warehouses (automatic warehouse, automated distribution center)
- Exercise facilities (gymnasium, stadium, live facilities)
- Transportation (road, railway, subway, car)
- Ship (guest room, cargo ship)
- Space (satellite launch test site)
Originally, there are inherent vibration components in facilities due to the characteristics (rigidity) of the materials and structures that form the building. In addition, various vibrations occur due to the presence of vibration. Sources include people, machines, fluids, magnetostriction, vehicles, and sound pressure.
These vibrations sometimes lead to noise disturbances. Sound can be heard by vibrating a medium such as air, but when a floor or wall vibrates greatly in a building, it vibrates the air and becomes a sound, which causes noise disturbance in places other than the vibration source... In this way, the sound generated due to the vibration transmitted through the structure, such as floors, walls, and piping, is known as solid sound.
Moreover, in the state-of-the-art research facilities and production plants where nanotechnology has advanced, even insensitivity level vibrations that are far below the microtremors of the ground can affect the accuracy of equipment. The magnitude of the vibration (displacement) is a micro level (micron (10-3 mm) to nanometer (10-6 mm)) that cannot be discerned by humans.
On the other hand, an earthquake has a large vibration effect, not only in one facility, but in a wide area. Seismic activity on the earth is active in the orogenic belts from the Himalayas to the Alps and the Pacific Rim orogens, but Japan is also located in the Pacific Rim orogens, and earthquakes with a seismic intensity of the 5-6 classes occur on average once every two years. A seismic intensity 7 class occurs once every 30 years. During the 60 years that are the legal life of the structure, it will have to endure a series of strong earthquakes.