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Encyclopedia > Structural engineering
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Structural engineering is a field of engineering that deals with the design of structural systems with the purpose of supporting and resisting various loads. Though other disciplines touch on this field, a physical object or system is truly considered a part of structural engineering, regardless of its central scientific or industrial application, if its main function is designed to resist loads and dissipate energy. Structural engineering is usually considered a specialty discipline within civil engineering, but it can also be studied in its own right.[1] Image File history File links No higher resolution available. ... Engineering is the discipline and profession of applying scientific knowledge and utilizing natural laws and physical resources in order to design and implement materials, structures, machines, devices, systems, and processes that realize a desired objective and meet specified criteria. ... The term structural system in structural engineering refers to load-resisting sub-system of a structure. ... Load may mean: Look up Load in Wiktionary, the free dictionary. ... The Falkirk Wheel in Scotland. ...

Burj Dubai, the world's tallest building, currently under construction in Dubai

A structural engineer is most commonly involved in the design of buildings and nonbuilding structures[2]but also plays an essential role in designing machinery where structural integrity of the design item impacts safety and reliability. Large man-made objects, from furniture to medical equipment to a variety of vehicles, require significant design input from a structural engineer. Image File history File links Size of this preview: 354 Ã— 598 pixelsFull resolution (662 Ã— 1119 pixel, file size: 76 KB, MIME type: image/jpeg) Burj Dubai, taken by me on August 9, 2007 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to... Image File history File links Size of this preview: 354 Ã— 598 pixelsFull resolution (662 Ã— 1119 pixel, file size: 76 KB, MIME type: image/jpeg) Burj Dubai, taken by me on August 9, 2007 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to... Burj Dubai (Arabic: â€Ž Dubai Tower) is a skyscraper currently under construction in Dubai, United Arab Emirates, and is currently the tallest man-made structure on Earth. ... For many millennia the record holder for worlds tallest structure was clearly defined (see table below. ... Location of Dubai in the UAE Coordinates: , Country Emirate Dubai Incorporated (town) June 9, 1833 Incorporated (emirate) December 2, 1971 Founder Maktoum bin Bati bin Suhail (1833) Seat Dubai Subdivisions Towns and villages Jebel Ali Hatta Al Hunaiwah Al Aweer Al Hajarain Al Lusayli Al Marqab Al Shindagha Al Faq... structural engineer is an engineering profession who practices structural engineering. ... Old Executive Office Building, Washington D.C. Bank of China Tower, Hong Kong, China In architecture, construction, engineering and real estate development the word building may refer to one of the following: Any man-made structure used or intended for supporting or sheltering any use or continuous occupancy, or An... Nonbuilding structures, also referred to simply as structures, are those not designed for continuous human occupancy. ... A machine is any mechanical or electrical device that transmits or modifies energy to perform or assist in the performance of tasks. ... For the UK band, see Furniture (band). ...

Structural engineers ensure that their designs satisfy a given "design intent", predicated on safety (e.g. structures do not collapse without due warning), or performance criteria (e.g. vibration control), or serviceability (e.g. floor vibration and building sway do not result in discomfort for the occupants). Structural engineers are responsible for making creative and efficient use of funds and materials to achieve these goals. [2] In the design of floor systems in buildings vibrations caused by walking, dancing, mechanical equipment or other rhythmic excitation may cause an annoyance to the occupants or impede the function of sensitive equipment. ...

## Etymology

The term structural derives from the Latin word structus, which is "to pile, build assemble". The first use of the term structure was c.1440.[3] The term engineer derives from the old French term engin, meaning "skill, cleverness" and also 'war machine'. This term in turn derives from the Latin word ingenium, which means "inborn qualities, talent," and is constructed of in- "in" + gen-, the root of gignere, meaning "to beget, produce." The term engineer is related to ingenious.[4]

The term structural engineer is generally applied only to those who have completed a degree in structural engineering. The term engineer in isolation varies widely in its use and application, and can, depending on the geographical location of its use, refer to many different technical and creative professions in its common usage.

## The structural engineer

Main article: Structural engineer
Gustave Eiffel, pioneer of the use of iron in structural engineering

Structural engineers often specialise in particular fields, such as bridge engineering, building engineering, pipeline engineering, industrial structures or special structures such as vehicles or aircraft.

Structural engineering has existed since humans first started to construct their own structures. It became a more defined and formalised profession with the emergence of the architecture profession as distinct from the engineering profession during the industrial revolution in the late 19th Century. Until then, the architect and the structural engineer were often one and the same - the master builder. Only with the understanding of structural theories that emerged during the 19th and 20th century did the professional structural engineer as it is known now begin to exist. This article is about building architecture. ... A Watt steam engine, the steam engine that propelled the Industrial Revolution in Britain and the world. ... For other uses, see Architect (disambiguation). ... structural engineer is an engineering profession who practices structural engineering. ...

The role of a structural engineer today involves a significant understanding of both static and dynamic loading, and the structures that are available to resist them. The complexity of modern structures often requires great creativity in order to support and resist the loads they are subjected to. A structural engineer will typically have a three, four or five year undergraduate degree, followed by a minimum of three years of professional practice before being able to be considered fully qualified.[5]

Structural engineers are licensed or accredited by different learned societies and regulatory bodies around the world (for example, the Institution of Structural Engineers in the UK)[5]. Depending on the degree course they have studied, they may be accredited (or licensed) as just structural engineers, or as civil and as structural engineers. Image:IStructE logo. ...

## History of structural engineering

Statuette of Imhotep, in the Louvre, Paris, France

Throughout ancient and medieval history most architectural design and construction was carried out by artisans, such as stone masons and carpenters, rising to the role of master builder. No theory of structures existed and understanding of how structures stood up was extremely limited, and based almost entirely on empirical evidence of 'what had worked before'. Knowledge was retained in guilds and seldom supplanted by advances. Structures were repetitive, and increases in scale were incremental.[6] An artisan, also called a craftsman,[1] is a skilled manual worker who uses tools and machinery in a particular craft. ... Look up mason in Wiktionary, the free dictionary. ... The Carpenters were a vocal and instrumental duo, consisting of siblings Karen and Richard Carpenter. ... The Master Builder (Norwegian: Bygmester Solness) is a play by Norwegian dramatist Henrik Ibsen. ... A guild is an association of persons of the same trade or pursuits, formed to protect mutual interests and maintain standards of morality or conduct. ...

### Pre-Twentieth Century structural engineering developments

Archimedes is said to have remarked about the lever: "Give me a place to stand on, and I will move the Earth."
• In the 26th century BC, the Great Pyramid of Giza was constructed in Egypt. It remained the largest man-made structure for millenia and was considered an unsurpassed feat in architecture until the 19th century AD.[7]
• In the 3rd Century BC Archimedes published his work On the Equilibrium of Planes in two volumes, in which he sets out the Law of the Lever, stating:
 “ Equal weights at equal distances are in equilibrium, and equal weights at unequal distances are not in equilibrium but incline towards the weight which is at the greater distance. ”
Archimedes used the principles derived to calculate the areas and centers of gravity of various geometric figures including triangles, paraboloids, and hemispheres. [8] Archimedes work on this and his work on calculus and geometry, together with Euclidian geometry, underpin much of the mathematics and understanding of structures in modern structural engineering.
Aqueduct of Segovia
• In the 15th and 16th centuries, Leonardo da Vinci, despite lacking beam theory and calculus produced many engineering designs based on scientific observations and rigour, including a design for a bridge to span the Bosporus. Though dismissed at the time, the design has since been judged to be both feasible and structurally valid[10]
Galileo Galilei. Portrait in crayon by Leoni
• In 1638 Galileo published Dialogues Relating to Two New Sciences[11], outlining the sciences of the strength of materials and the motion of objects (essentially defining gravity as a force giving rise to a constant acceleration). It was the first establishment of a scientific approach to structural engineering, including the first attempts to develop a theory for beams. This is also regarded as the beginning of structural analysis, the mathematical representation and design of building structures.
Leonhard Euler portrait by Johann Georg Brucker
• In the 18th Century Leonhard Euler pioneered much of the mathematics and many of the methods which allow structural engineers to model and analyse structures. Specifically, he developed the Euler-Bernoulli beam equation with Daniel Bernoulli circa 1750 - the fundamental theory underlying most structural engineering design.[15][16]
• In the 18th Century Johann (Jean) Bernoulli (1667-1748) and Daniel Bernoulli (1700-1782) are credited with formulating the theory of virtual work, providing a tool using equilibrium of forces and compatibility of geometry to solve structural problems. In 1717 Jean Bernoulli wrote to Pierre Varignon explaining the principle of virtual work, while in 1726 Daniel Bernoulli wrote of the "composition of forces".[17]
• In 1821 Claude-Louis Navier formulated the general theory of elasticity in a mathematically usable form. In his lecons of 1826 he explored a great range of different structural theory, and was the first to highlight that the role of a structural engineer is not to understand the final, failed state of a structure, but to prevent that failure in the first place.[15] In 1826 he also established the elastic modulus as a property of materials independent of the second moment of area, allowing engineers for the first time to both understand structural behaviour and structural materials.[18]
• In1873 Carlo Alberto Castigliano presented his dissertation "Intorno ai sistemi elastici", which contains his theorem for computing displacement as partial derivative of the strain energy.[19]

### Modern developments in structural engineering

Bessemer converter, Kelham Island Museum, Sheffield, England (2002)
Belper North Mill
Forth Bridge
Eiffel Tower under construction in July 1888.
Salginatobel Bridge by Robert Maillart.
Screenshot from the ANSYS finite element analysis software.

• In 1824, Portland Cement was patented by the engineer Joseph Aspdin as "a superior cement resembling Portland Stone", British Patent no. 5022. Although different forms of cement already existed (Pozzolanic cement was used by the Romans as early as 100 B.C. and even earlier by the ancient Greek and Chinese civilizations) and were in common usage in Europe from the 1750s, the discovery made by Aspdin used commonly available, cheap materials, making concrete construction an economical possibility.[20]
• In 1848 Joseph-Louis Lambot built a rowing boat of ferrocement - the forerunner of modern reinforced concrete. He patented his system of mesh reinforcement and concrete in 1855, one year after W.B. Wilkinson also patented a similar system.[21]
• In the 1850s Henry Bessemer developed the Bessemer process to produce steel. He gained patents for the process in 1855 and 1856 and successfully completed the conversion of cast iron into cast steel in 1858.[22] Eventually mild steel would replace both wrought iron and cast iron as the preferred metal for construction.
• In 1867, a reinforced concrete planting tub was patented by Joseph Monier in Paris, using steel mesh reinforcement similar to that used by Lambot and Wilkinson. Monier took the idea forward, filing several patents for tubs, slabs and beams, leading eventually to the Monier system of reinforced structures, the first use of steel reinforcement bars located in areas of tension in the structure. [23]
• During the late 19th Century, great advancements were made in the use of cast iron, gradually replacing wrought iron as a material of choice. Ditherington Flax Mill in Shrewsbury, designed by Charles Bage, was the first building in the world with an interior iron frame. It was built in 1797. In 1792 William Strutt had attempted to build a fireproof mill at Belper in Derby (Belper West Mill), using cast iron columns and timber beams within the depths of brick arches that formed the floors. The exposed beam soffits were protected against fire by plaster. This mill at Belper was the world's first attempt to construct fireproof buildings, and is the first example of fire engineering. This was later improved upon with the construction of Belper North Mill, a collaboration between Strutt and Bage, which by using a full cast iron frame represented the world's first "fire proofed" building.[24][25]
• In 1889, the wrought-iron Eiffel Tower was built by Gustave Eiffel and Maurice Koechlin, demonstrating the potential of construction using iron, despite the fact that steel construction was already being used elsewhere.
• From 1892 onwards François Hennebique's firm used his patented reinforced concrete system to build thousands of structures throughout Europe. Thaddeus Hyatt in the US and Wayss & Freitag in Germany also patented systems. The firm AG für Monierbauten constructed 200 reinforced concrete bridges in Germany between 1890 and 1897 [26]
• During the first third of the 20th Century, Robert Maillart and others pioneered the use of reinforced concrete, and greatly furthered the understanding of its behaviour. Maillart noticed that many concrete bridge structures were significantly cracked, and as a result left the cracked areas out of his next bridge design - correctly believing that if the concrete was cracked, it was not contributing to the strength. Wilhelm Ritter formulated the truss theory for the shear design of reinforced concrete beams in 1899, and Emil Mörsch improved this in 1902. He went on to demonstrate that treating concrete in compression as a linear-elastic material was a conservative approximation of its behaviour[27]. Concrete design and analysis has been progressing ever since, with the development of analysis methods such as yield line theory, based on plastic analysis of concrete (as opposed to linear-elastic), and many different variations on the model for stress distributions in concrete in compression[28] [29]
• Prestressed concrete, pioneered by Eugène Freyssinet with a patent in 1928, gave a novel approach in overcoming the weakness of concrete structures in tension. Freyssinet constructed an experimental prestressed arch in 1908 and later used the technology in a limited form in the Plougastel Bridge in France in 1930. He went on to build six prestressed concrete bridges across the Marne River, firmly establishing the technology.[30]
• In 1930 Professor Hardy Cross’s developed his Moment Distribution Method, allowing the real stresses of many complex structures to be approximated quickly and accurately.[31]
• In the mid 20th Century John Fleetwood Baker developed the plasticity theory of structures, providing a powerful tool for the safe design of steel structures.[31]
• In 1941 Alexander Hrennikoff submitted his D.Sc thesis at MIT on the topic of discretization of plane elasticity problems using a lattice framework. This was the forerunner to the development of finite element analysis. In 1942, Richard Courant developed a mathematical basis for finite element analysis. This led in 1956 to the publication by J. Turner, R. W. Clough, H. C. Martin, and L. J. Topp's of a paper on the "Stiffness and Deflection of Complex Structures". This paper introduced the name "finite-element method" and is widely recognised as the first comprehensive treatment of the method as it is known today. [32]
• In the second half of the 20th century, Fazlur Khan, designed structural systems that remain fundamental to all high-rise skyscrapers and which he employed in his structural designs for the John Hancock Center in 1969 and Sears Tower in 1973.[33] Khan's central innovation in skyscraper design and construction was the idea of the "tube" and "bundled tube" structural systems for tall buildings.[34][35] Another innovation that Khan developed was the concept of X-bracing, which reduced the lateral load on the building by transferring the load into the exterior columns. This allowed for a reduced need for interior columns thus creating more floor space, and can be seen in the John Hancock Center.
• In 1987 Jörg Schlaich and Kurt Schafer published the culmination of almost ten years of work on the strut and tie method for concrete analysis - a tool to design structures with discontinuities such as corners and joints.[36]
• In the late 20th and early 21st Centuries the development of powerful computers has allowed finite element analysis to become a significant tool for structural analysis and design. The development of finite element programs has led to the ability to accurately predict the stresses in complex structures, and allowed significant advances in structural engineering design and architecture. In the 1960s and 70s computational analysis was used in a significant way for the first time on the design of the Sydney Opera House roof. Many modern structures could not be understood and designed without the use of computational analysis.[37]

### Significant structural failures

Main article: Structural failure
Mechanical failure modes
Buckling
Corrosion
Creep
Fatigue
Fracture
Melting
Thermal shock
Wear
Yielding
This box: view  talk  edit
The Dee bridge after its collapse
Fallen Tay Rail Bridge
Tacoma Narrows Bridge collapsing
Design change on the Hyatt Regency walkways.

• On the 24th May, 1847 the Dee Bridge collapsed as a train passed over it, with the loss of 5 lives. It was designed by Robert Stephenson, using cast iron girders reinforced with wrought iron struts. The bridge collapse was subject to one of the first formal inquiries into a structural failure. The result of the enquiry was that the design of the structure was fundamentally flawed, as the wrought iron did not reinforce the cast iron at all, and due to repeated flexing it suffered a brittle failure due to fatigue.[38]
• The Dee bridge disaster was followed by a number of cast iron bridge collapse, including the collapse of the first Tay Rail Bridge on the 28 December 1879, also when a train passed over it. 75 people lost their lives. The bridge failed because of poorly made cast iron, and the failure of the designer Thomas Bouch to consider wind loading on the bridge. The collapse resulted in cast iron largely being replaced by steel construction, and a complete redesign of the Forth Railway Bridge of 1890. The Forth Bridge was as a result the first entirely steel bridge in the world.[39]
• In 1940 the first Tacoma Narrows Bridge collapsed spectacularly due to wind induced resonant vibration with positive feedback (causing continually increasing amplitude). This collapse, and the research that followed, led to increased understanding of wind/structure interactions, including the phenomenon of flutter, a torsional mode of vibration. Several bridges were altered following the collapse to prevent a similar event occurring again. The only fatality was 'Tubby' the dog.[39]
• During 1954 two de Havilland Comet C1 jet airliners, the world's first commercial airliner, crashed with the loss of all on board. After lengthy investigations, and the grounding of all Comet airliners, the cause was discovered to be metal fatigue at the corners of the windows. The square corners had led to stress concentrations which after continual stress cycles from pressurisation and de-pressurisation, failed catastropically in flight. The research into the failures led to significant improvements in understanding of fatigue loading of airframes, and the redesign of the Comet and all subsequent airliners to incorporate rounded corners to doors and windows.
• On the 16 May 1968 the 22 storey residential tower Ronan Point in the London borough of Newham collapsed when a relatively small gas explosion on the 18th floor caused a structural wall panel to be blown away from the building. The tower was constructed of precast concrete, and the failure of the single panel caused one entire corner of the building to collapse. The panel was able to be blown out because there was insufficient reinforcement steel passing between the panels. This also meant that the loads carried by the panel could not be redistributed to other adjacent panels, because there was no route for the forces to follow. As a result of the collapse, building regulations were overhauled to prevent disproportionate collapse, and the understanding of precast concrete detailing was greatly advanced. Many similar buildings were altered or demolished as a result of the collapse.[40]
• On the 17 July 1981, two suspended walkways through the lobby of the Hyatt Regency in Kansas City, Missouri, collapsed, killing 114 people at a tea dance. The collapse was due to a late change in design, altering the method in which the rods supporting the walkways were connected to them, and inadvertently doubling the forces on the connection. The failure highlighted the need for good communication between design engineers and contractors, and rigorous checks on designs and especially on contractor proposed design changes. The failure is a standard case study on engineering courses around the world, and is used to teach the importance of ethics in engineering.[40][41]
• On 19 April 1995, the nine storey concrete framed Alfred P. Murrah Federal Building in Oklahoma was struck by a huge car bomb causing partial collapse, resulting in the deaths of 168 people. The bomb, though large, caused a significantly disproportionate collapse of the structure. The bomb blew all the glass off the front of the building and completely shattered a ground floor reinforced concrete column (see brisance). At second storey level a wider column spacing existed, and loads from upper storey columns were transferred into fewer columns below by girders at second floor level. The removal of one of the lower storey columns caused neighbouring columns to fail due to the extra load, eventually leading to the complete collapse of the central portion of the building. The bombing was one of the first to highlight the extreme forces that blast loading from terrorism can exert on buildings, and led to increased consideration of terrorism in structural design of buildings.[42]
• On 11 September 2001, the two towers of the World Trade Center in New York were struck by airplanes. Though the towers initially withstood the impact, the jet fuel on board caused fires which ultimately caused the buildings to collapse due to buckling failures in the perimeter gravity frame. Both towers collapsed in their entirety because as each floor collapsed, it fell on the floor below and caused it too to collapse. This mode of collapse is known as progressive collapse. The significant investigations into the collapse led to changes in the way tall buildings are designed to withstand both fire and terrorism, and the methods in which people escape in emergencies.

## Specialisations

### Building structures

Sydney Opera House, designed by Ove Arup & Partners, with the architect Jorn Utzon
Gare do Oriente in Lisbon, Portugal (1998), by the structural engineer and architect Santiago Calatrava

Structural building engineering is primarily driven by the creative manipulation of materials and forms and the underlying mathematical and scientific principles to achieve an end which fulfils its functional requirements and is structurally safe when subjected to all the loads it could reasonably be expected to experience, while being economical and practical to construct. This is subtly different to architectural design, which is driven by the creative manipulation of materials and forms, mass, space, volume, texture and light to achieve an end which is aesthetic, functional and often artistic.

The architect is usually the lead designer on buildings, with a structural engineer employed as a sub-consultant. The degree to which each discipline actually leads the design depends heavily on the type of structure. Many structures are structurally simple and led by architecture, such as multi-storey office buildings and housing, while other structures, such as tensile structures, shells and gridshells are heavily dependent on their form for their strength, and the engineer may have a more significant influence on the form, and hence much of the aesthetic, than the architect. Between these two extremes, structures such as stadia, museums and skyscrapers are complex both architecturally and structurally, and a successful design is a collaboration of equals. The worlds first steel tensile structure by Vladimir Shukhov (during construction), Nizhny Novgorod, 1896 The Sidney Myer Music Bowl in Kings Domain, Melbourne A tensile structure is a construction of elements carrying only tension and no compression or bending. ... The worlds first double curvature lattice steel Shell by V.G.Shukhov (during construction), Vyksa near Nizhny Novgorod, 1897 Thin-shell structures can be defined as curved structures capable of transmitting loads in more than two directions to supports. ... Multihalle in Mannheim, wooden gridshell structure designed with Frei Otto. ...

The structural design for a building must ensure that the building is able to stand up safely, able to function without excessive deflections or movements which may cause fatigue of structural elements, cracking or failure of fixtures, fittings or partitions, or discomfort for occupants. It must account for movements and forces due to temperature, creep, cracking and imposed loads. It must also ensure that the design is practically buildable within acceptable manufacturing tolerances of the materials. It must allow the architecture to work, and the building services to fit within the building and function (air conditioning, ventilation, smoke extract, electrics, lighting etc). The structural design of a modern building can be extremely complex, and requires a large team to complete. For other uses, see Temperature (disambiguation). ... Creep is the term used to describe the tendency of a solid material to slowly move or deform permanently under the influence of stresses. ...

Structural engineering specialties for buildings include:

This article does not cite any references or sources. ... Fire protection engineering (also known as fire engineering or fire safety engineering) is the application of science and engineering principles to protect people and their environments from the destructive effects of fire and smoke. ... For automobile roofs, see Sunroof. ... This article does not cite any references or sources. ... Wind Engineering is a field of engineering devoted to the analysis of wind effects on the natural and built environment. ...

### Civil engineering structures

The Millau Viaduct in France, designed by Michel Virlogeux with Foster & Partners

Civil structural engineering includes all structural engineering related to the built environment, excluding occupiable buildings. It includes: Image File history File links Metadata Size of this preview: 800 Ã— 600 pixelsFull resolutionâ€Ž (2,304 Ã— 1,728 pixels, file size: 1. ... Image File history File links Metadata Size of this preview: 800 Ã— 600 pixelsFull resolutionâ€Ž (2,304 Ã— 1,728 pixels, file size: 1. ... The Millau Viaduct (French: ) is a large cable-stayed road-bridge that spans the valley of the River Tarn near Millau in southern France. ... Michel Virlogeux was the chief engineer in the construction of the Millau Viaduct. ... Hearst Tower (New York City) Expo MRT Station, Mass Rapid Transit, Singapore. ... The Falkirk Wheel in Scotland. ...

Civil engineering structures are often subjected to very extreme forces, such as large variations in temperature, dynamic loads such as waves or traffic, or high pressures from water or compressed gases. They are also often constructed in corrosive environments, such as at sea, in industrial facilities or below ground.

### Mechanical structures

An Airbus A380, the world's largest passenger airliner

The design of static structures assumes they always have the same geometry (in fact, so-called static structures can move significantly, and structural engineering design must take this into account where necessary), but the design of moveable or moving structures must account for fatigue, variation in the method in which load is resisted and significant deflections of structures. Image File history File links Metadata No higher resolution available. ... Image File history File links Metadata No higher resolution available. ... The Airbus A380 is a double-deck, wide-body, four-engine airliner manufactured by the European corporation Airbus, an EADS subsidiary. ... In materials science, fatigue is the progressive, localised, and permanent structural damage that occurs when a material is subjected to cyclic or fluctuating strains at nominal stresses that have maximum values less than (often much less than) the static yield strength of the material. ...

The forces which parts of a machine are subjected to can vary significantly, and can do so at a great rate. The forces which a boat or aircraft are subjected to vary enormously and will do so thousands of times over the structure's lifetime. The structural design must ensure that such structures are able to endure such loading for their entire design life without failing.

These works can require mechanical structural engineering:

Airframe means the mechanical structure of an aircraft[1] and as generally used does not include the engines. ... Steel Pressure Vessel A pressure vessel is a closed, rigid container designed to hold gases or liquids at a pressure different from the ambient pressure. ... The body of a motor vehicle which is built around a chassis, rather than being of monocoque construction. ... A modern crawler type derrick crane with outriggers. ... For other uses, see Elevator (disambiguation). ... Escalators at Canary Wharf, London. ... Traditional boat building in South East Maluku, Indonesia. ...

## Structural elements

A statically determinate simply supported beam, bending under an evenly distributed load.

Any structure is essentially made up of only a small number of different types of elements: In statics, a construction is statically indeterminate when the static equilibrium equations are not sufficient to calculate the reactions on that construction. ...

• Columns
• Beams
• Plates
• Arches
• Shells
• Catenaries

### Columns

Table showing values of K for structural columns of various end conditions (adapted from Manual of Steel Construction, 8th edition, American Institute of Steel Construction, Table C1.8.1)
Main article: column

Columns are elements that carry only axial force - either tension or compression - or both axial force and bending. The design of a column must check the axial capacity of the element, and the buckling capacity. Image File history File links Size of this preview: 600 Ã— 600 pixelsFull resolution (962 Ã— 962 pixel, file size: 79 KB, MIME type: image/png) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Column ... Image File history File links Size of this preview: 600 Ã— 600 pixelsFull resolution (962 Ã— 962 pixel, file size: 79 KB, MIME type: image/png) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Column ... For other uses, see Column (disambiguation). ...

The buckling capacity is the capacity of the element to withstand the propensity to buckle because of inaccuracies in straightness or position of the column. Its capacity depends upon its geometry, material and the effective length of the column, which depends upon the restraint conditions at the top and bottom of the column. This is shown in the table on the right, where the effective length is K * l where l is the real length of the column.

The capacity of a column to carry axial load depends on the degree of bending it is subjected to, and vice versa. This is represented on an interaction chart and is a complex non-linear relationship.

### Beams

Main article: Beam (structure)

A beam may be: A statically determinate beam, bending under an evenly distributed load. ...

• cantilevered (supported at one end only with a fixed connection)
• simply supported (supported vertically but able to rotate at the supports)
• continuous (supported vertically and unable to rotate at the supports)

Beams are elements which carry pure bending only. Bending causes one section of a beam (divided along its length) to go into compression and the other section into tension. The compression section must be designed to resist buckling and crushing, while the tension section must be able to adequately resist the tension. A schematic image of two cantilevers. ...

#### Trusses

Main article: Truss
The McDonnell Planetarium by Gyo Obata in St Louis, USA, a concrete shell structure
A masonry arch
1. Keystone 2. Voussoir 3. Extrados 4. Impost 5. Intrados 6. Rise 7. Clear span 8. Abutment

Trusses are usually utilised to span large distances, where it would be uneconomical and unattractive to use solid beams.

### Plates

Plates carry bending in two directions. A concrete flat slab is an example of a plate. Plates are understood by using continuum mechanics, but due to the complexity involved they are most often designed using a codified empirical approach, or computer analysis. Continuum mechanics is a branch of physics (specifically mechanics) that deals with continuous matter, including both solids and fluids (i. ...

They can also be designed with yield line theory, where an assumed collapse mechanism is analysed to give an upper bound on the collapse load (see Plasticity). This is rarely used in practice.

### Shells

Main article: Thin-shell structure

Shells derive their strength from their form, and carry forces in compression in two directions. A dome is an example of a shell. They can be designed by making a hanging-chain model, which will act as a catenary in pure tension, and inverting the form to achieve pure compression. The worlds first double curvature lattice steel Shell by V.G.Shukhov (during construction), Vyksa near Nizhny Novgorod, 1897 Thin-shell structures can be defined as curved structures capable of transmitting loads in more than two directions to supports. ... Multihalle in Mannheim, wooden gridshell structure designed with Frei Otto. ...

### Arches

Main article: Arch

Arches carry forces in compression in one direction only, which is why it is appropriate to build arches out of masonry. They are designed by ensuring that the line of thrust of the force remains within the depth of the arch. For other uses, see Arch (disambiguation). ...

### Catenaries

Main article: Tensile structure

Catenaries derive their strength from their form, and carry transverse forces in pure tension by deflecting (just as a tightrope will sag when someone walks on it). They are almost always cable or fabric structures. A fabric structure acts as a catenary in two directions. The worlds first steel tensile structure by Vladimir Shukhov (during construction), Nizhny Novgorod, 1896 The Sidney Myer Music Bowl in Kings Domain, Melbourne A tensile structure is a construction of elements carrying only tension and no compression or bending. ...

### Seismic base isolators

Main article: Vibration control

Base isolation is a collection of structural elements of a building that should substantially decouple the building's superstructure from the shaking ground thus protecting the building's integrity; see, e.g., the shake table testing of a kind of seismic base isolators called Earthquake Protectors. This technology, which is a kind of seismic vibration control, can be applied both to newly designed buildings and to seismic upgrading of existing structures. Normally, excavations are made around the building which is separated from its foundation. Steel or reinforced concrete beams replace the connections to the foundation, while under these, the isolating pads, or seismic base isolators, replace the material removed. While the base isolation tends to restrict transmition of the ground motion to the building, it also keeps the building positioned properly over the foundation. Old Executive Office Building, Washington D.C. Bank of China Tower, Hong Kong, China In architecture, construction, engineering and real estate development the word building may refer to one of the following: Any man-made structure used or intended for supporting or sheltering any use or continuous occupancy, or An... In physics, decoupling is the general phenomenon in which the interactions between some physical objects (such as elementary particles) disappear. ... // Sociological concept In social sciences, superstructure is the set of socio-psychological feedback loops that maintain a coherent and meaningful structure in a given society, or part thereof. ...

## Structural engineering theory

Figure of a bolt in shear. Top figure illustrates single shear, bottom figure illustrates double shear.

Structural engineering depends upon a detailed knowledge of loads, physics and materials to understand and predict how structures support and resist self-weight and imposed loads. To apply the knowledge successfully a structural engineer will need a detailed knowledge of mathematics and of relevant empirical and theoretical design codes. Look up bolt in Wiktionary, the free dictionary. ... In physics and mechanics, shear refers to a deformation that causes parallel surfaces to slide past one another (as opposed to compression and tension, which cause parallel surfaces to move towards or away from one another). ... Loads is the title of a 1995 compilation of the British pop group Happy Mondays. ... A magnet levitating above a high-temperature superconductor demonstrates the Meissner effect. ... material is the substance or matter from which something is or can be made, or also items needed for doing or creating something. ... For other meanings of mathematics or uses of math and maths, see Mathematics (disambiguation) and Math (disambiguation). ...

The criteria which govern the design of a structure are either serviceability (criteria which define whether the structure is able to adequately fulfil its function) or strength (criteria which define whether a structure is able to safely support and resist its design loads). A structural engineer designs a structure to have sufficient strength and stiffness to meet these criteria. Look up strength in Wiktionary, the free dictionary. ... Stiffness is the resistance of an elastic body to deflection or deformation by an applied force. ...

Loads imposed on structures are supported by means of forces transmitted through structural elements. These forces can manifest themselves as:

• tension (axial force)
• compression (axial force)
• shear
• bending (or flexure (a bending moment is a force multiplied by a distance, or lever arm, hence producing a turning effect or torque)

Tension is a reaction force applied by a stretched string (rope or a similar object) on the objects which stretch it. ... Physical compression is the result of the subjection of a material to compressive stress, resulting in reduction of volume. ... Shear stress is a stress state where the stress is parallel or tangential to a face of the material, as opposed to normal stress when the stress is perpendicular to the face. ... Figure 1. ... This article or section does not adequately cite its references or sources. ... For other senses of this word, see torque (disambiguation). ...

Live loads are transitory or temporary loads, and are relatively unpredictable in magnitude. They may include the weight of a building's occupants and furniture, the forces/weights of wind and water, temperature, vibration, seismic activity, blast loading, fire loading and temporary loads the structure is subjected to during construction.

Dead loads are permanent, and may include the weight of the structure itself and all major permanent components. Dead load may also include the weight of the structure itself supported in a way it wouldn't normally be supported, for example during construction.

### Strength

Strength depends upon material properties. The strength of a material depends on its capacity to withstand axial stress or shear stress. The strength of a material is measured in force per unit area (newtons per square millimetre or N/mm², or the equivalent megapascals or MPa). Strength of materials is materials science applied to the study of engineering materials and their mechanical behavior in general (such as stress, deformation, strain and stress-strain relations). ... Stress has different meanings in different fields: Look up stress in Wiktionary, the free dictionary. ... Shear stress is a stress state where the stress is parallel or tangential to a face of the material, as opposed to normal stress when the stress is perpendicular to the face. ...

A structure fails the strength criterion when the stress (force divided by area of material) induced by the loading is greater than the capacity of the structural material to resist the load without breaking, or when the strain (percentage extension) is so great that the element no longer fulfils its function (yield). Stress has different meanings in different fields: Look up stress in Wiktionary, the free dictionary. ... This article is about the deformation of materials. ... The yield strength or yield point of a material is defined in engineering and materials science as the stress at which a material begins to deform plastically. ...

Tensile strength isthe measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. ... Compressive strength is the capacity of a material to withstand axially directed pushing forces. ... Shear strength in engineering is a term used to describe the strength of a material or component against the type of yield or structural failure where the material or component fails in shear. ...

### Stiffness

Stiffness depends upon material properties and geometry. The stiffness of a structural element of a given material is the product of the material's Young's modulus and the element's second moment of area. Stiffness is measured in force per unit length (newtons per millimetre or N/mm), and is equivalent to the 'force constant' in Hooke's Law. Stiffness is the resistance of an elastic body to deflection or deformation by an applied force. ... For other uses, see Geometry (disambiguation). ... In solid mechanics, Youngs modulus (E) is a measure of the stiffness of a given material. ... The second moment of area, also known as the area moment of inertia or second moment of inertia, is a property of a shape that is used to predict its resistance to bending and deflection which are directly proportional. ... Hookes law accurately models the physical properties of common mechanical springs for small changes in length. ...

The deflection of a structure under loading is dependent on its stiffness. The dynamic response of a structure to dynamic loads (the natural frequency of a structure) is also dependent on its stiffness. This article or section does not cite any references or sources. ... fdg--220. ...

In a structure made up of multiple structural elements, the elements will carry loads in proportion to their relative stiffness - the stiffer an element, the more load it will attract.

A structure is considered to fail the chosen serviceability criteria if it is insufficiently stiff to have acceptably small deflection or dynamic response under loading. Look up stiff in Wiktionary, the free dictionary. ... This article or section does not cite any references or sources. ... The word dynamics can refer to: a branch of mechanics; see dynamics (mechanics) the volume of music; see dynamics (music) When used referring to mechanics, it is referring to the study of the motion of both rigid bodies and particles. ...

The inverse of stiffness is the flexibility. â€¹ The template below (Expand) is being considered for deletion. ...

In structural engineering, the flexibility method is the classical consistent deformation method for computing member forces and displacements in structural systems. ... In structural engineering, the matrix stiffness method (or simply stiffness method) is a matrix method that makes use of the members stiffness relations for computing member forces and displacements in structures. ...

### Safety Factors

The safe design of structures requires a design approach which takes account of the statistical likelihood of the failure of the structure. Structural design codes are based upon the assumption that both the loads and the material strengths vary with a normal distribution. This article is about the field of statistics. ... The normal distribution, also called the Gaussian distribution, is an important family of continuous probability distributions, applicable in many fields. ...

The job of the structural engineer is to ensure that the chance of overlap between the distribution of loads on a structure and the distribution of material strength of a structure is acceptably small (it is impossible to reduce that chance to zero).

In design for strength the following safety factors for loads are typical:

The safety factors for material strength vary depending on the material and the use it is being put to and on the design codes applicable in the country or region.

In design for serviceability criteria it is normal to use factors of 1.0 for the loads.

### Newton's Laws of Motion

The most important natural laws for structural engineering are Newton's Laws of Motion Newtons First and Second laws, in Latin, from the original 1687 edition of the Principia Mathematica. ... Newtons First and Second laws, in Latin, from the original 1687 edition of the Principia Mathematica. ...

Newton's First Law states that every body perseveres in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by force impressed.

Newton's Second Law states that the rate of change of momentum of a body is proportional to the resultant force acting on the body and is in the same direction. Mathematically, F=ma (force = mass x acceleration).

Newton's Third Law states that all forces occur in pairs, and these two forces are equal in magnitude and opposite in direction.

With these laws it is possible to understand the forces on a structure and how that structure will resist them. The Third Law requires that for a structure to be stable all the internal and external forces must be in equilibrium. This means that the sum of all internal and external forces on a free-body diagram must be zero: A standard definition of mechanical equilibrium is: A system is in mechanical equilibrium when the sum of the forces, and torque, on each particle of the system is zero. ... A free body diagram is a pictorial representation often used by physicists to show all contact and non-contact forces acting on the given free body. ...

• $sum vec F = 0$: the vectorial sum of the forces acting on the body equals zero. This translates to
Σ H = 0: the sum of the horizontal components of the forces equals zero;
Σ V = 0: the sum of the vertical components of forces equals zero;
• $sum vec M = 0$: the sum of the moments (about an arbitrary point) of all forces equals zero.

For other uses, see Force (disambiguation). ... It has been suggested that this article or section be merged with torque. ...

### Statical determinacy

A structural engineer must understand the internal and external forces of a structural system consisting of structural elements and nodes at their intersections. In statics, a construction is statically indeterminate when the static equilibrium equations are not sufficient to calculate the reactions on that construction. ...

A statically determinate structure can be fully analysed using only consideration of equilibrium, from Newton's Laws of Motion.

A statically indeterminate structure has more unknowns than equilibrium considerations can supply equations for (see simultaneous equations). Such a system can be solved using consideration of equations of compatibility between geometry and deflections in addition to equilibrium equations, or by using virtual work. In Mathematics simultaneous equations are a set of equations containing multiple variables. ... A force F, which may be real (actual) or imaginary (fictitious), acting on a particle is said to do virtual work when the particle is imagined to undergo a real or imaginary displacement component D in the direction of the force. ...

If a system is made up of b bars, j pin joints and r support reactions, then it cannot be statically determinate if the following relationship does not hold:

r + b = 2j

It should be noted that even if this relationship does hold, a structure can be arranged in such a way as to be statically indeterminate.[43]

### Elasticity

Main article: Elasticity (physics)

Much engineering design is based on the assumption that materials behave elastically. For most materials this assumption is incorrect, but empirical evidence has shown that design using this assumption can be safe. Materials that are elastic obey Hooke's Law, and plasticity does not occur. Elasticity is a branch of physics which studies the properties of elastic materials. ... Hookes law accurately models the physical properties of common mechanical springs for small changes in length. ...

For systems that obey Hooke's Law, the extension produced is directly proportional to the load:

$vec{mathbf{F}}=-kvec{mathbf{x}}$

where

x is the distance that the spring has been stretched or compressed away from the equilibrium position, which is the position where the spring would naturally come to rest [usually in meters],
F is the restoring force exerted by the material [usually in newtons], and
k is the force constant (or spring constant). This is the stiffness of the spring. The constant has units of force per unit length (usually in newtons per metre)

### Plasticity

Comparison of Tresca and Von Mises Criteria
Main article: Plasticity (physics)

Some design is based on the assumption that materials will behave plastically.[31] It applies to ductile materials. It can be used for reinforced concrete structures assuming they are underreinforced and the steel reinforcement fails before the concrete. Image File history File links Tresca_stress_2D.png Based on Image:Von_mises_stress_2D.png File links The following pages link to this file: Henri Tresca ... Image File history File links Tresca_stress_2D.png Based on Image:Von_mises_stress_2D.png File links The following pages link to this file: Henri Tresca ... For other uses, see Plasticity. ... For other uses, see Plasticity. ... Ductility is the physical property of being capable of sustaining large plastic deformations without fracture (in metals, such as being drawn into a wire). ...

Plasticity theory states that the point at which a structure collapses (reaches yield) lies between an upper and a lower bound on the load, defined as follows:

• If, for a given external load, it is possible to find a distribution of moments that satisfies equilibrium requirements, with the moment not exceeding the yield moment at any location, and if the boundary conditions are satisfied, then the given load is a lower bound on the collapse load.
• If, for a small increment of displacement, the internal work done by the structure, assuming that the moment at every plastic hinge is equal to the yield moment and that the boundary conditions are satisfied, is equal to the external work done by the given load for that same small increment of displacement, then that load is an upper bound on the collapse load.

If the correct collapse load is found, the two methods will give the same result for the collapse load.[44]

Plasticity theory depends upon a correct understanding of when yield will occur. A number of different models for stress distibution and approximations to the yield surface of plastic materials exist:[15] Yield surface is described in three dimensional space of principal stresses (), and encompasses the elastic region of material behavior. ...

Mohrs circle is a graphical representation of any 2-D stress state proposed by Christian Otto Mohr in 1882. ... Henri Tresca (1814â€“1884) was French Mechanical Engineer, professor of Conservatoire National des Arts et MÃ©tiers in Paris. ...

### The Euler-Bernoulli beam equation

Deflection of a cantilever under a point load (f) in engineering
Main article: Euler-Bernoulli beam equation

The Euler-Bernoulli beam equation defines the behaviour of a beam element (see below). It is based on five assumptions: Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... This vibrating glass beam may be modeled as a cantilever beam with acceleration, variable linear density, variable section modulus, some kind of dissipation, springy end loading, and possibly a point mass at the free end. ...

(1) continuum mechanics is valid for a bending beam
(2) the stress at a cross section varies linearly in the direction of bending, and is zero at the centroid of every cross section.
(3) the bending moment at a particular cross section varies linearly with the second derivative of the deflected shape at that location.
(4) the beam is composed of an isotropic material
(5) the applied load is orthogonal to the beam's neutral axis and acts in a unique plane. Continuum mechanics is a branch of physics (specifically mechanics) that deals with continuous matter, including both solids and fluids (i. ... Stress is a measure of force per unit area within a body. ... Cross section may refer to the following In geometry, Cross section is the intersection of a 3-dimensional body with a plane. ... Centroid of a triangle In geometry, the centroid or barycenter of an object in -dimensional space is the intersection of all hyperplanes that divide into two parts of equal moment about the hyperplane. ... Cross section may refer to the following In geometry, Cross section is the intersection of a 3-dimensional body with a plane. ... It has been suggested that this article or section be merged with torque. ...

A simplified version of Euler-Bernoulli beam equation is:

$EI frac{d^4 u}{d x^4} = w(x).,$

Here u is the deflection and w(x) is a load per unit length. E is the elastic modulus and I is the second moment of area, the product of these giving the stiffness of the beam. An elastic modulus, or modulus of elasticity, is the mathematical description of an object or substances tendency to be deformed when a force is applied to it. ... The second moment of area, also known as the area moment of inertia or second moment of inertia, is a property of a shape that is used to predict its resistance to bending and deflection which are directly proportional. ... Stiffness is the resistance of an elastic body to deflection or deformation by an applied force. ...

This equation is very common in engineering practice: it describes the deflection of a uniform, static beam.

Successive derivatives of u have important meaning:

• $textstyle{u},$ is the deflection.
• $textstyle{frac{partial u}{partial x}},$ is the slope of the beam.
• $textstyle{EIfrac{partial^2 u}{partial x^2}},$ is the bending moment in the beam.
• $textstyle{-frac{partial}{partial x}left(EIfrac{partial^2 u}{partial x^2}right)},$ is the shear force in the beam.

A bending moment manifests itself as a tension and a compression force, acting as a couple in a beam. The stresses caused by these forces can be represented by: Figure 1. ... Shearing in continuum mechanics refers to the occurrence of a shear strain, which is a deformation of a material substance in which parallel internal surfaces slide past one another. ... For other meanings, see Couple A Couple is or are two equal and opposite forces whose lines of action do not coincide. ...

$sigma = frac{My}{I} = E y frac{partial^2 u}{partial x^2},$

where σ is the stress, M is the bending moment, y is the distance from the neutral axis of the beam to the point under consideration and I is the second moment of area. This equation allows a structural engineer to assess the stress in a structural element when subjected to a bending moment. An axis in the cross section of a beam, shaft or the like along which there are no longitudinal stresses / strains. ... The second moment of area, also known as the area moment of inertia or second moment of inertia, is a property of a shape that is used to predict its resistance to bending and deflection which are directly proportional. ...

### Buckling

A column under a centric axial load exhibiting the characteristic deformation of buckling.
A demonstration model illustrating the effects of lateral-torsional buckling on an I-section beam.

When subjected to compressive forces it is possible for structural elements to deform significantly due to the destabilising effect of that load. The effect can be initiated or exacerbated by possible inaccuracies in manufacture or construction. Image File history File links A column exhibiting the characteristic deformation of buckling under a centric axial load. ... Image File history File links A column exhibiting the characteristic deformation of buckling under a centric axial load. ... Image File history File links Ltb. ... Image File history File links Ltb. ...

The Euler Buckling formula defines the axial compression force which will cause a strut (or column) to fail in buckling. This article is about engineering. ... A strut is a structural component designed to resist longitudinal compression. ...

$F=frac{pi^2 EI}{(Kl)^2}$

where

F = maximum or critical force (vertical load on column),
E = modulus of elasticity,
I = area moment of inertia, or second moment of area
l = unsupported length of column,
K = column effective length factor, whose value depends on the conditions of end support of the column, as follows.
For both ends pinned (hinged, free to rotate), K = 1.0.
For both ends fixed, K = 0.50.
For one end fixed and the other end pinned, K = 0.70.
For one end fixed and the other end free to move laterally, K = 2.0.

This value is sometimes expressed for design purposes as a critical buckling stress. For other uses, see Force (disambiguation). ... In solid mechanics, Youngs modulus (also known as the modulus of elasticity or elastic modulus) is a measure of the Stiffness of a given material. ... The second moment of area, also known as the second moment of inertia and the area moment of inertia, is a property of a shape that is used to predict its resistance to bending and deflection. ... Stress has different meanings in different fields: Look up stress in Wiktionary, the free dictionary. ...

$sigma=frac{pi^2 E}{(frac{Kl}{r})^2}$

where

σ = maximum or critical stress
r = the least radius of gyration of the cross section

Other forms of buckling include lateral torsional buckling, where the compression flange of a beam in bending will buckle, and buckling of plate elements in plate girders due to compression in the plane of the plate. Stress has different meanings in different fields: Look up stress in Wiktionary, the free dictionary. ... The radius of gyration is a defined measure for the dimension of an object, a surface, or an ensemble of points. ...

## Materials

Stress-strain curve for low-carbon steel. Hooke's law (see above) is only valid for the portion of the curve between the origin and the yield point.
1. Ultimate strength
2. Yield strength-corresponds to yield point.
3. Rupture
4. Strain hardening region
5. Necking region.

Structural engineering depends on the knowledge of materials and their properties, in order to understand how different materials support and resist loads. Image File history File links Stress_v_strain_A36_2. ... Image File history File links Stress_v_strain_A36_2. ... A stress-strain curve is a graph derived from measuring load (stress - Ïƒ) versus extension (strain - Îµ) for a sample of a material. ... For other uses, see Steel (disambiguation). ... Yield strength, or the yield point, is defined in engineering as the amount of strain that a material can undergo before moving from elastic deformation into plastic deformation. ... Cold Work is a quality imparted on a material as a result of plastic deformation. ...

Common structural materials are:

### Iron

#### Wrought Iron

Main article: Wrought iron

Wrought iron is the simplest form of iron, and is almost pure iron (typically less than 0.15% carbon). It usually contains some slag. Its uses are almost entirely obsolete, and it is no longer commercially produced. A wrought iron railing in Troy, New York. ... Slag is also an early play by David Hare. ...

Wrought iron is very poor in fires. It is ductile, malleable and tough. It does not corrode as easily as steel. For the hazard, see corrosive. ...

#### Cast Iron

Main article: Cast iron

Cast iron is a brittle form of iron which is weaker in tension than in compression. It has a relatively low melting point, good fluidity, castability, excellent machinability and wear resistance. Though almost entirely replaced by steel in building structures, cast irons have become an engineering material with a wide range of applications, including pipes, machine and car parts. Cast iron usually refers to grey cast iron, but can mean any of a group of iron-based alloys containing more than 2% carbon (alloys with less carbon are carbon steel by definition). ...

Cast iron retains high strength in fires, despite its low melting point. It is usually around 95% iron, with between 2.1-4% carbon and between 1-3% silicon. It does not corrode as easily as steel.

#### Steel

The 630 foot (192 m) high, stainless-clad (type 304) Gateway Arch in Saint Louis, Missouri's.
Main article: Steel
Main article: Structural steel

Steel is a iron alloy with between 0.2 and 1.7% carbon. Gateway Arch, 2001, by Rick Dikeman File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Gateway Arch, 2001, by Rick Dikeman File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... The Jefferson National Expansion Memorial is located in St. ... Nickname: Gateway City, Gateway to the West, or Mound City Motto: Official website: http://stlouis. ... For other uses, see Steel (disambiguation). ... Structural steel is steel construction material, a profile, formed with a specific shape or cross section and certain standards of chemical composition and strength. ... Steel frame usual refers to a building technique in which a skeleton frame of steel is constructed to support the building which is attached to the frame. ...

Steel is used extremely widely in all types of structures, due to its relatively low cost, high strength to weight ratio and speed of construction.

Steel is a ductile material, which will behave elastically until it reaches yield (point 2 on the stress-strain curve), when it becomes plastic and will fail in a ductile manner (large strains, or extensions, before failure at point 3 on the curve). Steel is equally strong in tension and compression. Yield may mean: In economics, yield is a measure of the amount of income an investment generates over time (related to return on investment). ... For other uses, see Plastic (disambiguation). ...

Steel is very weak in fires, and must be protected in most buildings. Because of its high strength to weight ratio, steel buildings typically have low thermal mass, and require more energy to heat (or cool) than similar concrete buildings.

The elastic modulus of steel is approximately 205 GPa An elastic modulus, or modulus of elasticity, is the mathematical description of an object or substances tendency to be deformed when a force is applied to it. ... The initials GPA can refer, among other things, to Grade Point Average; see Grade (education) Guinness Peat Aviation General Practice Australia, a private, independent medical accreditation society Greyhound Pets of America This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

Steel is very prone to corrosion (rust). For other uses, see Rust (disambiguation). ...

#### Stainless Steel

Main article: Stainless steel

Stainless steel is an iron-carbon alloy with a minimum of 10.5% chromium content. There are different types of stainless steel, containing different proportions of iron, carbon, molybdenum, nickel. It has similar structural properties to steel, although its strength varies significantly. The 630 foot (192 m) high, stainless-clad (type 304) Gateway Arch defines St. ... General Name, Symbol, Number molybdenum, Mo, 42 Chemical series transition metals Group, Period, Block 6, 5, d Appearance gray metallic Standard atomic weight 95. ... For other uses, see Nickel (disambiguation). ...

It is rarely used for primary structure, and more for architectural finishes and building cladding.

It is highly resistant to corrosion and staining.

### Concrete

The interior of the Sagrada Familia, constructed of reinforced concrete to a design by Gaudi
Main article: Concrete
Main article: Reinforced concrete

Concrete is brittle material, which is very strong in compression and very weak in tension. It behaves non-linearly at all times. Because it has essentially zero strength in tension, it is almost always used as reinforced concrete, a composite material. It is a mixture of sand, aggregate, cement and water. It is placed in a mould, or form, as a liquid, and then it sets (goes off), due to a chemical reaction between the water and cement. The reaction produces a significant amount of heat. Reinforced concrete at Sainte Jeanne dArc Church (Nice, France): architect Jacques Dror, 1926â€“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. ... For other uses, see Sand (disambiguation). ... For other uses, see Cement (disambiguation). ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ...

Concrete increases in strength continually from the day it is cast. It shrinks over time as it dries out, and deforms over time due to a phenomenon called creep. It's strength depends highly on how it is mixed, poured, cast, compacted and cured (kept wet while setting). It can be cast into any shape that a form can be made for. Its colour, quality and finish depend upon the complexity of the structure, the material used for the form and the skill of the pourer. Creep is the term used to describe the tendency of a solid material to slowly move or deform permanently under the influence of stresses. ...

Concrete is a non-linear, non-elastic material, and will fail suddenly, with a brittle failure, unless adequate reinforced with steel. An "under-reinforced" concrete element will fail with a ductile manner, as the steel will fail before the concrete. An "over-reinforced" element will fail suddenly, as the concrete will fail first. Reinforced concrete elements should be designed to be under-reinforced so users of the structure will receive warning of impending collapse.

The elastic modulus of concrete can vary widely and depends on the concrete mix, age and quality, as well as the on the type and duration of loading applied to it. It is usually taken as approximately 25 GPa for long-term loads once it has attained its full strength (usually considered to be at 28 days after casting). It is taken as approximately 38 Gpa for very short-term loading, such as footfalls. An elastic modulus, or modulus of elasticity, is the mathematical description of an object or substances tendency to be deformed when a force is applied to it. ... The initials GPA can refer, among other things, to Grade Point Average; see Grade (education) Guinness Peat Aviation General Practice Australia, a private, independent medical accreditation society Greyhound Pets of America This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

Concrete has very favourable properties in fire - it is not adversely affected by fire until it reaches very high temperatures. It also has very high mass, so it is good for providing sound insulation and heat retention (leading to lower energy requirements for the heating of concrete buildings). This is offset by the fact that producing and transporting concrete is very energy intensive.

### Aluminium

Stress vs. Strain curve typical of aluminum
1. Ultimate Strength
2. Yield strength
3. Proportional Limit Stress
4. Rupture
5. Offset Strain (typically 0.002).
Main article: aluminium
Main article: Aluminum alloy

Aluminium is a soft, lightweight, malleable metal. The yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has about one-third the density and stiffness of steel. It is ductile, and easily machined, cast, and extruded. Image File history File links Stress_v_strain_Aluminum_2. ... Image File history File links Stress_v_strain_Aluminum_2. ... Yield strength, or the yield point, is defined in engineering as the amount of strain that a material can undergo before moving from elastic deformation into plastic deformation. ... Aluminum redirects here. ... Aluminium alloys or aluminum alloys are alloys of aluminum, often with copper, zinc, manganese, silicon, or magnesium. ...

Corrosion resistance is excellent due to a thin surface layer of aluminium oxide that forms when the metal is exposed to air, effectively preventing further oxidation. The strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper.

Aluminium is used in some building structures (mainly in facades) and very widely in aircraft engineering because of its good strength to weight ratio. It is a relatively expensive material.

In aircraft it is gradually being replaced by carbon composite materials.

### Composites

Main article: Composites

Composite materials are used increasingly in vehicles and aircraft structures, and to some extent in other structures. They are increasingly used in bridges, especially for conservation of old structures such as Coalport cast iron bridge built in 1818. Composites are often anisotropic (they have different material properties in different directions) as they can be laminar materials. They most often behave non-linearly and will fail in a brittle manner when overloaded. Image File history File linksMetadata Download high resolution version (2185x1543, 625 KB) Rutan VariEze (UK registration G-VEZE) at Kemble Airfield, Gloucestershire, England. ... Image File history File linksMetadata Download high resolution version (2185x1543, 625 KB) Rutan VariEze (UK registration G-VEZE) at Kemble Airfield, Gloucestershire, England. ... The Rutan Model 31 VariEze is a composite, canard aircraft designed by Burt Rutan. ... Composite materials (or composites for short) are engineering materials made from two or more components. ... Coalport is a village in Shropshire on the River Severn at grid reference SJ700021, shortly downstream of Ironbridge. ...

They provide extremely good strength to weight ratios, but are also very expensive. The manufacturing processes, which are often extrusion, do not currently provide the economical flexibility that concrete or steel provide. The most commonly used in structural applications are glass-reinforced plastics. It has been suggested that Fiber-reinforced plastic be merged into this article or section. ...

### Masonry

A brick wall built using Flemish Bond
Main article: Masonry

Masonry has been used in structures for hundreds of years, and can take the form of stone, brick or blockwork. Masonry is very strong in compression but cannot carry tension (because the mortar between bricks or blocks is unable to carry tension). Because it cannot carry tension, it also cannot carry bending, so masonry walls become unstable at relatively small heights. High masonry structures require stabilisation against lateral loads from buttresses (as with the flying buttresses seen in many European medieval churches) or from windposts. Flemish Bond (Bricklaying). ... Flemish Bond (Bricklaying). ... Flemish bond. ... This article refers to the building structure component; for the fraternal organization, see Freemasonry. ... Mortar has several meanings: Mortar (weapon) fires shells at a much lower velocity and higher ballistic arc than other ordnance Paintball mortar fires paintballs or water balloons filled with paint Mortar (masonry), material used in masonry to fill the gaps between bricks and bind them together Mortar (firestop), hydraulic cementitious... A buttress (and mostly concealed, a flying buttress) supporting walls at the Palace of Westminster Three different types of buttress: diagonal, on the statues plinth; an ordinary buttress supporting a flying buttress, to the right of the statue; a small ordinary buttress to the right side of the picture... Flying buttresses at Bath Abbey, Bath, England. ...

Historically masonry was constructed with no mortar or with lime mortar. In modern times cement based mortars are used.

Since the widespread use of concrete, stone is rarely used as a primary structural material, often only appearing as a cladding, because of its cost and the high skills needed to produce it. Brick and concrete blockwork have taken its place.

Masonry, like concrete, has good sound insulation properties and high thermal mass, but is generally less energy intensive to produce. It is just as energy intensive as concrete to transport.

### Timber

The reconstructed Globe Theatre, London, by Buro Happold
Main article: Timber

Wood is strong in tension and compression, but can be weak in bending due to its fibrous structure. Wood is relatively good in fire as it chars, which provides the wood in the centre of the element with some protection and allows the structure to retain some strength for a reasonable length of time.

### Other structural materials

Bamboo scaffolding can reach great heights.

structural engineer is an engineering profession who practices structural engineering. ... This is a list of notable structural engineers, people who were trained in or practiced structural engineering and who are notable enough for a Wikipedia article. ... for building and structual design see; Architect Architects are a metal band from Brighton in southern England. ... 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. ... The Falkirk Wheel in Scotland. ... Mechanical Engineering is an engineering discipline that involves the application of principles of physics for analysis, design, manufacturing, and maintenance of mechanical systems. ...

## References

• Leonhardt, A. (1964). "Vom Caementum zum Spannbeton, Band III (From Cement to Prestressed Concrete)". Bauverlag GmbH.
• Mörsch, E. (Stuttgart, 1908). "Der Eisenbetonbau, seine Theorie und Anwendun, (Reinforced Concrete Construction, its Theory an Application)". Konrad Wittwer, 3th edition.
• Hognestad, E. "A Study of Combined Bending and Axial Load in Reinforced Concrete Members". University of Illinois, Engineering Experiment Station, Bulletin Series N. 399.
• Dr P.C.J. Hoogenboom. "Historical Overview of Concrete Modelling".
• Schlaich, J., K. Schäfer, M. Jennewein (1987). "Toward a Consistent Design of Structural Concrete". PCI Journal, Special Report, Vol. 32, No. 3.

## Notes

See above for references to publications and academic papers.

1. ^ History of Structural Engineering. University of San Diego. Retrieved on 2007-12-02.
2. ^ a b What is a structural engineer. Institution of Structural Engineers. Retrieved on 2007-12-02.
3. ^ Etymology of the word structure. etymonline.com. Retrieved on 2007-12-25.
4. ^ Etymology of engine, engineer. etymonline.com. Retrieved on 2007-12-25.
5. ^ a b Routes to membership. Institution of Structural Engineers. Retrieved on 2007-12-25.
6. ^ a b Victor E. Saouma. Lecture notes in Structural Engineering. University of Colorado. Retrieved on 2007-11-02.
7. ^ Kazi, Najma (24 November, 2007). Seeking Seamless Scientific Wonders: Review of Emilie Savage-Smith's Work. FSTC Limited. Retrieved on 2008-02-01.
8. ^ Heath,T.L.. The Works of Archimedes (1897). The unabridged work in PDF form (19 MB). Archive.org. Retrieved on 2007-10-14.
9. ^ Mariam Rozhanskaya and I. S. Levinova (1996), "Statics", p. 642, in Morelon, Régis & Rashed, Roshdi (1996), Encyclopedia of the History of Arabic Science, vol. 2-3, Routledge, pp. 614-642, ISBN 0415020638 :

"Using a whole body of mathematical methods (not only those inherited from the antique theory of ratios and infinitesimal techniques, but also the methods of the contemporary algebra and fine calculation techniques), Arabic scientists raised statics to a new, higher level. The classical results of Archimedes in the theory of the centre of gravity were generalized and applied to three-dimensional bodies, the theory of ponderable lever was founded and the 'science of gravity' was created and later further developed in medieval Europe. The phenomena of statics were studied by using the dynamic apporach so that two trends - statics and dynamics - turned out to be inter-related withina single science, mechanics. The combination of the dynamic apporach with Archimedean hydrostatics gave birth to a direction in science which may be called medieval hydrodynamics. [...] Numerous fine experimental methods were developed for determining the specific weight, which were based, in particular, on the theory of balances and weighing. The classical works of al-Biruni and al-Khazini can by right be considered as the beginning of the application of experimental methods in medieval science." Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 336th day of the year (337th in leap years) in the Gregorian calendar. ... Image:IStructE logo. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 336th day of the year (337th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 359th day of the year (360th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 359th day of the year (360th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 359th day of the year (360th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 306th day of the year (307th in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 32nd day of the year in the Gregorian calendar. ... Internet Archive, San Francisco The Internet Archive (archive. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 287th day of the year (288th in leap years) in the Gregorian calendar. ... The Encyclopedia of the History of Arabic Science is a three-volume encyclopedia covering the history of Arabic contributions to science, mathematics and technology which had a tremendous influence on the rise of the European Renaissance. ... Routledge is an imprint for books in the humanities part of the Taylor & Francis Group, which also has Brunner-Routledge, RoutledgeCurzon and RoutledgeFalmer divisions. ... Science, and particularly geometry and astronomy, was linked directly to the divine for most medieval scholars. ...

10. ^ Renaissance Man. Museum of Science, Boston. Retrieved on 07-12-05.
11. ^ Galilei, Galileo. Dialogues Concerning Two New Sciences. ISBN 0486600998.
12. ^ Allan Chapman (2005). England's Leornardo: Robert Hooke and the Seventeenth Century's Scientific Revolution. CRC Press. ISBN 0750309873.
13. ^ Newton, Isaac;Leseur, Thomas; Jacquier, François (1822). Philosophiæ Naturalis Principia Mathematica. Oxford University.
14. ^ Stillwell, John (2002). Mathematics and its History. Springer, p.159. ISBN 0387953361.
15. ^ a b c Heyman, Jacques (1999). The Science of Structural Engineering. Imperial College Press, 69. ISBN 1860941893.
16. ^ a b Bradley, Robert E.; Sandifer, Charles Edward (2007). Leonhard Euler: Life, Work and Legacy. Elsevier. ISBN 0444527281.
17. ^ Dugas, René (1988). A History of Mechanics. Courier Dover Publications, 231. ISBN 0486656322.
18. ^ Hosford, William F. (2005). Mechanical Behavior of Materials. Cambridge University Press, p.35. ISBN 0521846706.
19. ^ Castigliano, Carlo Alberto (translator: Andrews, Ewart S.) (1966). The Theory of Equilibrium of Elastic Systems and Its Applications. Dover Publications.
20. ^ Prentice, John E. (1990). Geology of Construction Materials. Springer, p.171. ISBN 041229740X.
21. ^ Nedwell,P.J.; Swamy,R.N.(ed) (1994). Ferrocement:Proceedings of the Fifth International Symposium. Taylor & Francis, p.27. ISBN 0419197001.
22. ^ Swank, James Moore (1965). History of the Manufacture of Iron in All Ages. Ayer Publishing, p.395. ISBN 0833734636.
23. ^ Kirby, Richard Shelton (1990). Engineering in History. Courier Dover Publications, p.476. ISBN 0486264122.
24. ^ Blank, Alan; McEvoy, Michael; Plank, Roger (1993). Architecture and Construction in Steel. Taylor & Francis, p.2. ISBN 0419176608.
25. ^ Labrum, E.A. (1994). Civil Engineering Heritage. Thomas Telford, p.23. ISBN 072771970X.
26. ^ Leonhardt. p.41
27. ^ Mörsch, E. p.83
29. ^ Hoogenboom, P.C.J.
30. ^ Hewson, Nigel R. (2003). Prestressed Concrete Bridges: Design and Construction. Thomas Telford. ISBN 0727727745.
31. ^ a b c Heyman, Jacques (1998). Structural Analysis: A Historical Approach. Cambridge University Press, p.101. ISBN 0521622492.
32. ^ Turner, J.; Clough, R.W.; Martin, H.C.; Topp, L.J. (1956). "Stiffness and Deflection of Complex Structures". Journal of Aeronautical Science (Issue 23).
33. ^ Ali Mir (2001). Art of the Skyscraper: the Genius of Fazlur Khan. Rizzoli International Publications. ISBN 0847823709.
34. ^ Chris H. Luebkeman (1996). Tube-in-Tube. Retrieved on 2008-02-22.
35. ^ Chris H. Luebkeman (1996). Bundled Tube. Retrieved on 2008-02-22.
36. ^ Schlaich, J., K. Schäfer, M. Jennewein
37. ^ MacNeal, Richard H. (1994). Finite Elements: Their Design and Performance. Marcel Dekker. ISBN 0824791622.
38. ^ Petroski, Henry (1994). Design Paradigms: Case Histories of Error and Judgment in Engineering. Cambridge University Press, p.81. ISBN 0521466490.
39. ^ a b Scott, Richard (2001). In the Wake of Tacoma: Suspension Bridges and the Quest for Aerodynamic Stabilitya. ASCE Publications, p.139. ISBN 0784405425.
40. ^ a b Feld, Jacob; Carper, Kenneth L. (1997). Construction Failure. John Wiley & Sons, p.8. ISBN 0471574775.
41. ^ Whitbeck, Caroline (1998). Ethics in Engineering Practice and Research. Cambridge University Press, p.115. ISBN 0521479444.
42. ^ Virdi, K.S. (2000). Abnormal Loading on Structures: Experimental and Numerical Modelling. Taylor & Francis, p.108. ISBN 0419259600.
43. ^ Dym, Clive L. (1997). Structural Modeling and Analysis. Cambridge University Press, p.98. ISBN 0521495369.
44. ^ Nilson, Arthur H.; Darwin, David; Dolan, Charles W. (2004). Design of Concrete Structures. McGraw-Hill Professional, p.486. ISBN 0072483059.

2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 53rd day of the year in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 53rd day of the year in the Gregorian calendar. ...

Results from FactBites:

 Structural engineering - Wikipedia, the free encyclopedia (392 words) Structural engineering is a field of engineering that deals with the design of any structural system(s), the purpose of which is to support and resist various loads. Most commonly structural engineers are involved in the design of buildings and nonbuilding structures, but also play an essential role in designing machinery where structural integrity of the design item is a matter of safety and reliability. Typically, entry-level structural engineers may design simple beams, columns, and floors of a new building, including calculating the loads on each member and the load capacity of various building materials (steel, timber, masonry, concrete).
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