Earthquake engineering

Earthquake -proof construction means the entire effort, buildings must be designed so equip or retrofit to withstand earthquakes up to a certain thickness.

• 3.1 elastomeric bearings
• 3.2 Lead core storage
• 3.3 plain bearings
• 3.4 sliding pendulum

• 4.1 Nuclear power plants

Standardization

As design rules apply throughout Europe since its appear the Euro codes. The " Design of structures for earthquake resistance " is 8 ( EN 1998-1 to 6) regulated in the standards of Euro code. The to -country differences in boundary conditions, such as the expected earthquake intensities and ground accelerations are recorded in the respective National User documents.

Germany

For Germany, the inherited version of the Euro codes, DIN EN 1998 and, with its six parts. Precursor was the DIN standard DIN 4149 " Buildings in German earthquake zones - loads, analysis and design of buildings ." Until further notice, the normative already withdrawn standard DIN 4149:2005 construction law applies since the Euro Code 8 is not in the lists of the building inspectorate the technical building regulations of the federal states.

An important component of the German edition of the Euro codes is a national user document. The design is a seismic zone map contained therein are based, which was already included in DIN 4149. The conditions laid down in the map zones are based on the 475- year earthquake, an earthquake with a certain strength, which is exceeded in 50 years with a probability of 10%.

The majority of the Federal territory shall be deemed not at risk from earthquakes, that is, the earthquake occurring once in 475 years, a statistical average has an intensity ≤ 6 on the European Macroseismic Scale (EMS ) on. The most vulnerable areas of zone 3 ( EMS intensity I ≥ 7.5) will be around Basel and Aachen and southern Württemberg. As large areas on both sides of the Rhine, South Württemberg, the Danube Valley are to be endangered ( including zone 0) to about the Altmühltherme mouth and the Vogtland region and its wider surroundings to about Leipzig and finally the Alps and the surrounding foothills of the Alps.

Decisive for the real risk at the site is beyond the local underground.

Method of construction

Construction methods that allow for horizontal loading large deformations and only with advance notice ( ductile, not brittle ) failure are considered to be beneficial. Will withstand earthquakes designed and constructed, which may include:

• Steel structures
• Reinforced concrete structures in situ concrete
• Steel - reinforced concrete composite construction
• Wood construction
• Truss

In addition, the following design principles have a beneficial effect on the resistance to earthquake loading:

• Statically redundant systems,
• Redundant components,
• Symmetrical ground plan of the building,
• Arrangement vertically through ongoing massive cores,
• Horizontal stiffeners, eg by shear walls,
• Ductile materials and compounds.

Seismic isolation

Decoupling from their substrate structures to reduce the effect of the seismic waves of the building can be achieved by different types of interference. The essential principle is based on an increase in the natural vibration period of the building together with the storage. The horizontal forces occurring can be reduced by shifting the response spectrum of the building.

Elastomeric bearings

Elastomeric bearings, as they are also used in bridge construction work, damping, and are suitable for large shear deformation ability also for earthquake isolation.

Lead core storage

Lead- bearing core composed of a rubber mounting with an additional lead core, the damping acts, and absorbs energy by plastic deformation.

Plain bearings

Plain bearings allow the horizontal movement of the building on the ground and are usually used in combination with other methods of absorption and cushioning.

Sliding pendulum

These structural bearings combine different methods and using a concave slide plate. They have been used, among others, the Acropolis Museum.

Soft parts such as a floating storage or the suspension of a suspension bridge are further possibilities of storage of buildings to reduce the burden of earthquakes.

Scientists at the University of Marseille have developed a simulation that suggests that Rayleigh waves can be derived by concentric rings of selected materials and so building would be protected in the center of the plant. However, a practical application for it is not foreseeable.

Special buildings

Nuclear power plants

The Fukushima nuclear disaster since March 2011 drew world attention to the fact that nuclear power plants can not withstand any quake and that they can be severely damaged despite their sometimes massive construction of tidal waves.

After the devastating earthquake in Kobe in 1995, in which more than 6,400 people died, the rules were tightened in Japan. Since then built reactors have at least the strength of earthquakes 7.75 can withstand; in high-risk areas even quake to 8.25. The Tohoku Earthquake of 2011, however, had a moment magnitude of 9.0.

In California (November 2011) Work two old nuclear power plants, which are often mentioned in connection with the issue of earthquake safety: the San Onofre nuclear power plant (since 1968) and the Diablo Canyon nuclear power plant (since 1984/1985 ). The latter is 3 km away from an earthquake column (the one discovered during construction ); both located near the San Andreas Fault.