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In engineering, a foundation is the element of a structure which connects it to the ground or more rarely, water (as with floating structures), transferring loads from the structure to the ground. Foundations are generally considered either shallow or deep. [1] Foundation engineering is the application of soil mechanics and rock mechanics (geotechnical engineering) in the design of foundation elements of structures.
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Foundations provide the structure's stability from the ground:
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The design and the construction of a well-performing foundation must possess some basic requirements: [2]
Buildings and structures have a long history of being built with wood in contact with the ground. [3] [4] Post in ground construction may technically have no foundation. Timber pilings were used on soft or wet ground even below stone or masonry walls. [5] In marine construction and bridge building a crisscross of timbers or steel beams in concrete is called grillage. [6]
Perhaps the simplest foundation is the padstone, a single stone which both spreads the weight on the ground and raises the timber off the ground. [7] Staddle stones are a specific type of padstone.
Dry stone and stones laid in mortar to build foundations are common in many parts of the world. Dry laid stone foundations may have been painted with mortar after construction. Sometimes the top, visible course of stone is hewn, quarried stones. [8] Besides using mortar, stones can also be put in a gabion. [9] One disadvantage is that if using regular steel rebars, the gabion would last much less long than when using mortar (due to rusting). Using weathering steel rebars could reduce this disadvantage somewhat.
Rubble trench foundations are a shallow trench filled with rubble or stones. These foundations extend below the frost line and may have a drain pipe which helps groundwater drain away. They are suitable for soils with a capacity of more than 10 tonnes/m2 (2,000 pounds per square foot).
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Often called footings, are usually embedded about a meter or so into soil. One common type is the spread footing which consists of strips or pads of concrete (or other materials) which extend below the frost line and transfer the weight from walls and columns to the soil or bedrock.
Another common type of shallow foundation is the slab-on-grade foundation where the weight of the structure is transferred to the soil through a concrete slab placed at the surface. Slab-on-grade foundations can be reinforced mat slabs, which range from 25 cm to several meters thick, depending on the size of the building, or post-tensioned slabs, which are typically at least 20 cm for houses, and thicker for heavier structures.
Another way to install ready-to-build foundations that is more environmentally friendly is to use screw piles. Screw pile installations have also extended to residential applications, with many homeowners choosing a screw pile foundation over other options. Some common applications for helical pile foundations include wooden decks, fences, garden houses, pergolas, and carports.
Used to transfer the load of a structure down through the upper weak layer of topsoil to the stronger layer of subsoil below. There are different types of deep footings including impact driven piles, drilled shafts, caissons, screw piles, geo-piers[ clarification needed ] and earth-stabilized columns[ clarification needed ]. The naming conventions for different types of footings vary between different engineers. Historically, piles were wood, later steel, reinforced concrete, and pre-tensioned concrete.
A type of deep foundation which uses a single, generally large-diameter, structural element embedded into the earth to support all the loads (weight, wind, etc.) of a large above-surface structure.
Many monopile foundations [10] have been used in recent years for economically constructing fixed-bottom offshore wind farms in shallow-water subsea locations. [11] For example, a single wind farm off the coast of England went online in 2008 with over 100 turbines, each mounted on a 4.74-meter-diameter monopile footing in ocean depths up to 16 meters of water. [12]
A floating foundation is one that sits on a body of water, rather than dry land. This type of foundation is used for some bridges and floating buildings.
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Foundations are designed to have an adequate load capacity depending on the type of subsoil/rock supporting the foundation by a geotechnical engineer, and the footing itself may be designed structurally by a structural engineer. The primary design concerns are settlement and bearing capacity. When considering settlement, total settlement and differential settlement is normally considered. Differential settlement is when one part of a foundation settles more than another part. This can cause problems to the structure which the foundation is supporting. Expansive clay soils can also cause problems.
Geotechnical engineering, also known as geotechnics, is the branch of civil engineering and Geological engineering concerned with the engineering behavior of earth materials. It uses the principles of soil mechanics and rock mechanics to solve its engineering problems. It also relies on knowledge of geology, hydrology, geophysics, and other related sciences.
Retaining walls are relatively rigid walls used for supporting soil laterally so that it can be retained at different levels on the two sides. Retaining walls are structures designed to restrain soil to a slope that it would not naturally keep to. They are used to bound soils between two different elevations often in areas of inconveniently steep terrain in areas where the landscape needs to be shaped severely and engineered for more specific purposes like hillside farming or roadway overpasses. A retaining wall that retains soil on the backside and water on the frontside is called a seawall or a bulkhead.
Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with recent experiences with large earthquakes near urban centers, the need of seismic retrofitting is well acknowledged. Prior to the introduction of modern seismic codes in the late 1960s for developed countries and late 1970s for many other parts of the world, many structures were designed without adequate detailing and reinforcement for seismic protection. In view of the imminent problem, various research work has been carried out. State-of-the-art technical guidelines for seismic assessment, retrofit and rehabilitation have been published around the world – such as the ASCE-SEI 41 and the New Zealand Society for Earthquake Engineering (NZSEE)'s guidelines. These codes must be regularly updated; the 1994 Northridge earthquake brought to light the brittleness of welded steel frames, for example.
This page is a list of construction topics.
In construction or renovation, underpinning is the process of strengthening the foundation of an existing building or other structure. Underpinning may be necessary for a variety of reasons:
In geotechnical engineering, a caisson is a watertight retaining structure used, for example, to work on the foundations of a bridge pier, for the construction of a concrete dam, or for the repair of ships.
The Lilla Bommen named after the surrounding location of Lilla Bommen, commonly referred to as Läppstiftet , is an 86 m, 22-floor building housing office, networking and restaurant spaces in Gothenburg, Sweden. The building’s distinct post-modern architectural style, popularly referred to as “The Lipstick” due to its distinctive red-and-white colour schematic, was erected on the banks of Göta River in 1989 by Skanska Property West AB. The 32000 sqm office space which houses over 900 office workers, is a popular tourist destination for its top-floor lookout, Götheborgs Utkiken and restaurants such as the Restuarang Läppstiftet, has contributed to the landmark status of the building in the Central Gothenburg skyline.
A pile driver is a heavy-duty tool used to drive piles into soil to build piers, bridges, cofferdams, and other "pole" supported structures, and patterns of pilings as part of permanent deep foundations for buildings or other structures. Pilings may be made of wood, solid steel, or tubular steel, and may be driven entirely underwater/underground, or remain partially aboveground as elements of a finished structure.
A girder bridge is a bridge that uses girders as the means of supporting its deck. The two most common types of modern steel girder bridges are plate and box.
A deep foundation is a type of foundation that transfers building loads to the earth farther down from the surface than a shallow foundation does to a subsurface layer or a range of depths. A pile or piling is a vertical structural element of a deep foundation, driven or drilled deep into the ground at the building site.
A shallow foundation is a type of building foundation that transfers structural load to the earth very near to the surface, rather than to a subsurface layer or a range of depths, as does a deep foundation. Customarily, a shallow foundation is considered as such when the width of the entire foundation is greater than its depth. In comparison to deep foundations, shallow foundations are less technical, thus making them more economical and the most widely used for relatively light structures.
The Statnamic load test is a type of test for assessing the load-carrying capacity of deep foundations which is faster and less expensive than the static load test. The Statnamic test was conceived in 1985, with the first prototype tests carried out in 1988 through collaboration between Berminghammer Foundation Equipment of Canada and TNO Building Research of the Netherlands. Guidance on rapid load pile testing can be found in: Methods for Axial Compressive Force Pulse (Rapid) Testing of Deep Foundations. Sanken D7383 - 08 Standard Test.
Screw piles, sometimes referred to as screw-piles, screw piers, screw anchors, screw foundations, ground screws, helical piles, helical piers, or helical anchors are a steel screw-in piling and ground anchoring system used for building deep foundations. Screw piles are typically manufactured from high-strength steel using varying sizes of tubular hollow sections with helical flights.
The Franki piling system is a method used to drive expanded base cast-in-situ concrete (Franki) piles. It was developed by Belgian Engineer Edgard Frankignoul in 1909.
A grade beam or grade beam footing is a component of a building's foundation. It consists of a reinforced concrete beam that transmits the load from a bearing wall into spaced foundations such as pile caps or caissons. It is used in conditions where the surface soil’s load-bearing capacity is less than the anticipated design loads.
Offshore geotechnical engineering is a sub-field of geotechnical engineering. It is concerned with foundation design, construction, maintenance and decommissioning for human-made structures in the sea. Oil platforms, artificial islands and submarine pipelines are examples of such structures. The seabed has to be able to withstand the weight of these structures and the applied loads. Geohazards must also be taken into account. The need for offshore developments stems from a gradual depletion of hydrocarbon reserves onshore or near the coastlines, as new fields are being developed at greater distances offshore and in deeper water, with a corresponding adaptation of the offshore site investigations. Today, there are more than 7,000 offshore platforms operating at a water depth up to and exceeding 2000 m. A typical field development extends over tens of square kilometers, and may comprise several fixed structures, infield flowlines with an export pipeline either to the shoreline or connected to a regional trunkline.
The tripod is a type of foundation for offshore wind turbines. The tripod is generally more expensive than other types of foundation. However, for large turbines and higher water depth, the cost disadvantage might be compensated when durability is also taken into account.
An Olivier pile is a drilled displacement pile:. This is an underground deep foundation pile made of concrete or reinforced concrete with a screw-shaped shaft which is performed without soil removal.
Marine construction is the process of building structures in or adjacent to large bodies of water, usually the sea. These structures can be built for a variety of purposes, including transportation, energy production, and recreation. Marine construction can involve the use of a variety of building materials, predominantly steel and concrete. Some examples of marine structures include ships, offshore platforms, moorings, pipelines, cables, wharves, bridges, tunnels, breakwaters and docks. Marine construction may require diving work, but professional diving is expensive and dangerous, and may involve relatively high risk, and the types of tools and equipment that can both function underwater and be safely used by divers are limited. Remotely operated underwater vehicles (ROVs) and other types of submersible equipment are a lower risk alternative, but they are also expensive and limited in applications, so when reasonably practicable, most underwater construction involves either removing the water from the building site by dewatering behind a cofferdam or inside a caisson, or prefabrication of structural units off-site with mainly assembly and installation done on-site.
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