Earthquake construction is a branch of architectural engineering concerned with making sure structures can withstand as severe an earthquake shock as possible given the materials available. An architectural engineer applies the skills of many engineering disciplines to the design, construction, operation, maintenance, and renovation of buildings while paying attention to their impacts on the surrounding environment. ... Look up Structure in Wiktionary, the free dictionary. ... An earthquake is a phenomenon that results from the sudden release of stored energy in the Earths crust that creates seismic waves. ...

When, the structure in question is a human habitation, the questions of surviving earthquake damage become much more serious. Examples of inhabited structures collapsing during earthquakes abound and are sadly all too frequent. Areas of the world frequently hit by fatal earthquake damage include Japan, Turkey, Algeria, and countless other regions on or near tectonic plate boundaries. The tectonic plates of the world were mapped in the second half of the 20th century. ...

Earlier in mankind's history (during the Neolithic, for instance), mankind lived in tents, which can withstand earthquakes quite well. We moved on to more comfortable structures of timber, mud brick, limestone, wattle and daub, and even just stacked rubble. An array of Neolithic artifacts, including bracelets, axe heads, chisels, and polishing tools. ... A tent is a shelter, consisting of sheets of fabric or other material draped over or attached to a frame of poles and/or ropes. ... Timber in storage for later processing at a sawmill Timber is a term used to describe wood, either standing or that has been processed for use—from the time trees are felled, to its end product as a material suitable for industrial use—as structural material for construction or wood... A Mudbrick is an unfired brick made of clay. ... Limey shale overlaid by limestone. ... Categories: Stub | Construction ...

Some of these materials can be used to form solid, earthquake resistant structures. The important part is to use them wisely and with an understanding of how earthquakes really apply stresses to structures in practice. A structure might have all the appearances of stability, yet offer nothing but danger when an earthquake occurs. The crucial fact is that for safety, earthquake resistant construction techniques are as important as using the correct materials.

The specific mode of failure in an earthquake for most structures is the lateral (sideways) shaking. It frequently collapses walls, or moves them enough that the roof displaces and falls in.

Development of earthquake construction techniques

People living in frequently shaken areas like Japan started early in developing earthquake resistant buildings based on scientific study. Other countries likewise have and continue to study intensely how to make their citizens safer by understanding the problems posed by earthquakes more accurately.

Until the last 75 years or so, the only way to run "frequent tests" was to build on a fault and hope. Even then, earthquakes may only happen at any given spot every couple of hundred years, and construction techniques may not therefore take account of earthquake concerns. Modern shake tables have helped this; large motors and computer control systems try to precisely simulate earthquake movements.

Modern materials like concrete and reinforced concrete can help, but they also must withstand the same lateral (sideways) forces. Concrete being poured, raked and vibrated into place in residential construction in Toronto, Ontario, Canada. ... Reinforced concrete at Sainte Jeanne dArc Church (Nice, France): architect Jacques Dror, 1926–1933 Reinforced concrete, also called ferroconcrete in some countries, is concrete in which reinforcement bars (rebars) or fibers have been incorporated to strengthen a material that would otherwise be brittle. ...

Good earthquake construction pays careful heed to lateral forces. Proper concrete construction involves significant use of steel reinforcing bar (rebar). All the joints (where beams meet the columns), are carefully tied in with rebar. The concrete is of very high quality, and high strength. Brick infill is avoided for the walls. All structures should be properly anchored with anchor bolts. Rebar is common steel reinforcing bar, an important component of reinforced concrete and reinforced masonry structures. ... An anchor bolt is used to attach objects or structures to concrete. ...

Most countries have building codes that specify lateral strength. These codes are reliant on strict enforcement however.

Modern techniques

Modern construction techniques for earthquake zones involved designing structures that fail in predictable ways at predictable energy levels based on quantified earthquake severities. Many historic buildings have been subjected to a seismic retrofit. Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. ...

In the Los Angeles, California area, it is legal to build an apartment building near the San Andreas Fault with a setback limit of 50 feet. The apartments are typically designed to withstand an earthquake of 7.8 on the Richter Scale and fail in predictable ways at that level. The reasoning behind this is that an earthquake above 7.8 will bring down almost any structure and it is very difficult to design a reasonably priced structure that will withstand an earthquake above 7.8 on the Richter Scale. Nickname: City of Angels Location within Los Angeles County in the state of California Coordinates: State California County Los Angeles County Incorporated April 4, 1850 Government Type mayor-council  - Mayor Antonio Villaraigosa (D)  - City Attorney Rocky Delgadillo  - Governing body City Council Area    - City  498. ... View of the San Andreas Fault on the Carrizo Plain in central California, 35°07N, 119°39W The San Andreas Fault is a geological fault that runs a length of roughly 800 miles (1300 kilometres) through western and southern California in the United States. ... The Richter magnitude test scale (or more correctly local magnitude ML scale) assigns a single number to quantify the size of an earthquake. ...

In residential structures, buildings are designed to have the roof fall in the middle of a room, but stay up near the walls. People are always urged to take refuge in doorways and away from the middle of the room, and are therefore safe in these buildings. The structure of a residence may also be attached to the foundation with bolts to prevent the building from sliding off the foundation during shaking and collapsing.

Ground stabilization

Another failure mode of a structure in an earthquake involves the soil underneath the structure. In a strong enough seismic event, the soil can be shaken hard enough that it will break up, sometimes leading to the collapse of the structure sitting upon it. The most common method of protecting a structure against this failure mode is to flow cement into the soil beneath the structure. This method provides marginal support for the structure as the cement may not set up evenly. SOiL is a five-piece hard rock music group from Chicago, Illinois. ... In the most general sense of the word, cement is a binder, a substance which sets and hardens independently, and can bind other materials together. ...

An alternative method to infusing the ground with cement is under study. The method involves using a bacterium that secretes a viscous, sticky polymer that binds the soil together. In an experiment, the bacteria, Flavobacterium johnsoniae, was mixed with sand and was given several days to colonize the sand. The friction coefficient of the sand was measured and compared against sand without the bacteria colony. The sand colonized with the bacteria was almost twice as solid as the sand without the polymer producing bacteria. (Banagan, et al., 2005) Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Polymer is the term used to describe large molecules consisting of repeating structural units, or monomers, connected by covalent chemical bonds. ... Friction is the force that opposes the relative motion or tendency toward such motion of two surfaces in contact. ...

References

• Banagan, B.L., B.M. Wertheim, M.J.S. Roth, and L.F. Caslake (2005). "Increasing sand strength through the addition of bacteria". American Society for Microbiology meeting. June 5-9. Atlanta. Abstract