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 is an Alloy consisting mostly of Iron, with a Carbon content between 0 Materials are physical Substances used as inputs to production or Manufacturing. In Standardization, a profile consists of an agreed-upon subset and interpretation of a Specification. The shape ( OE sceap Eng created thing) of an object located in some space refers to the part of space occupied by the object as determined In Geometry, a cross section is the intersection of a body in 2-dimensional space with a line or of a body in 3-dimensional space with a plane etc Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties Structural steel shape, size, composition, strength, storage, etc, is regulated in most industrialised countries.
Structural steel, such as I-beams, have a large polar moment of inertia, which allows the beam to be very stiff in respect to its cross-sectional area.
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Common structural shapes
In most developed countries, the shapes available are set out in published standards, although a number of specialist and proprietary cross sections are also available. The term developed country, or advanced country, is used to categorize countries with developed Economies in which the tertiary and quaternary sectors In Geometry, a cross section is the intersection of a body in 2-dimensional space with a line or of a body in 3-dimensional space with a plane etc
- I-beam (I-shaped cross-section - in Britain these include Universal Beams (UB) and Universal Columns (UC); in Europe it includes the IPE, HE, HL, HD and other sections; in the US it includes Wide Flange (WF) and H sections)
- Z-Shape (half a flange in opposite directions)
- HSS-Shape (Hollow structural section also known as SHS (structural hollow section) and including square, rectangular, circular (pipe) and elliptical cross-sections)
- Angle (L-shaped cross-section)
- Channel (C-shaped cross-section)
- Tee (T-shaped cross-section)
- Rail profile (asymmetrical I-beam)
- Bar, a piece of metal, rectangular cross sectioned (flat) and long, but not so wide so as to be called a sheet. I-beams (also known as W-beams or double-T esp in Polish and German) are beams with an I- or H-shaped A hollow structural section (HSS is a type of metal profile with a hollow tubular cross section. Classification A square (regular Quadrilateral) is a special case of a Rectangle as it has four right angles and equal parallel sides In Geometry, a rectangle is defined as a Quadrilateral where all four of its angles are Right angles A rectangle with vertices ABCD would be denoted as A pipe is a tube or hollow cylinder used to convey materials or as a structural component In Mathematics, an ellipse (from the Greek ἔλλειψις literally absence) is a Conic section, the locus of points in a A Rail profile is a Hot rolled Steel profile of a specific Shape or cross section (an asymmetrical I-beam) designed A Rail profile is a Hot rolled Steel profile of a specific Shape or cross section (an asymmetrical I-beam) designed A Rail profile is a Hot rolled Steel profile of a specific Shape or cross section (an asymmetrical I-beam) designed Tramway track is used on tramways or Light rail operations Grooved rails (or girder rails are often used in order to make street running feasible The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across In Geometry, a rectangle is defined as a Quadrilateral where all four of its angles are Right angles A rectangle with vertices ABCD would be denoted as In Geometry, a cross section is the intersection of a body in 2-dimensional space with a line or of a body in 3-dimensional space with a plane etc Sheet metal is simply Metal formed into thin and flat pieces It is one of the fundamental forms used in Metalworking, and can be cut and bent into a variety
- Rod, a round or square and long piece of metal or wood, see also rebar and dowel. Circles are simple Shapes of Euclidean geometry consisting of those points in a plane which are at a constant Distance, called the Classification A square (regular Quadrilateral) is a special case of a Rectangle as it has four right angles and equal parallel sides The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across Wood is hard fibrous lignified structural tissue produced as secondary Xylem in the stems of Woody plants notably trees but also shrubs A rebar, or reinforcing bar, is a common Steel bar and is commonly used in Reinforced concrete and reinforced Masonry structures A dowel is a solid cylindrical rod, usually made of Wood, Plastic or Metal.
- Plate, sheet metal thicker than 6 mm or 1/4 in. Sheet metal is simply Metal formed into thin and flat pieces It is one of the fundamental forms used in Metalworking, and can be cut and bent into a variety
- Open web steel joist
While many sections are made by hot or cold rolling, others are made by welding together flat or bent plates (for example, the largest circular hollow sections are made from flat plate bent into a circle and seam-welded). Hot rolling is a Metalworking process where large pieces of Metal, such as slabs or billets are heated above their Recrystallization temperature and Cold rolling is a Metal working process in which metal is deformed by passing it through rollers at a temperature below its Recrystallization temperature Rolling is a fabricating process in which the Metal, Plastic, Paper, Glass, etc
Structural steels
Most industrialised countries prescribe a range of standard steel grades with different strengths, corrosion resistance and other properties.
Standard structural steels (Europe)
Most steels used throughout Europe are specified to comply with the European standard EN 10025. European Committee for Standardization or Comité Européen de Normalisation ( CEN) is a private non-profit organisation whose mission is to foster the European economy However, many national standards also remain in force.
Typical grades are described as 'S275J2' or 'S355K2W'. In these examples, 'S' denotes structural rather than engineering steel; 275 or 355 denotes the yield strength in newtons per square millimetre or the equivalent megapascals; J2 or K2 denotes the materials toughness by reference to Charpy impact test values; and the 'W' denotes weathering steel. The yield strength or yield point of a Material is defined in Engineering and Materials science as the stress at which a material Toughness, in Materials science and Metallurgy, is the resistance to Fracture of a material when stressed. The Charpy impact test, also known as the Charpy v-notch test, is a standardized high strain -rate test which determines the amount of Energy Weathering steel, best-known under the trademark COR-TEN steel is a group of Steel alloys which were developed to obviate the need for painting and form a stable Further letters can be used to designate normalised steel ('N' or 'NL'); quenched and tempered steel ('Q' or 'QL'); and thermomechanically rolled steel ('M' or 'ML'). Annealing, in Metallurgy and Materials science, is a Heat treatment wherein a material is altered causing changes in its properties such as strength A quench refers to a rapid Cooling. In Polymer chemistry and Materials science, quenching is used to prevent low-temperature processes such as phase
The normal yield strength grades available are 195, 235, 275, 355, 420, and 460, although some grades are more commonly used than others e. g. in the UK, almost all structural steel is grades S275 and S355. Higher grades are available in quenched and tempered material (500, 550, 620, 690, 890 and 960 - although grades above 690 receive little if any use in construction at present).
Standard structural steels (USA)
Steels used for building construction in the US use standard alloys identified and specified by ASTM International. ASTM International ( ASTM) originally known as the American Society for Testing and Materials is an international Standards organization that develops and publishes These steels have an alloy identification beginning with A and then two, three, or four numbers. The four-number AISI steel grades commonly used for mechanical engineering, machines, and vehicles are a completely different specification series.
The standard commonly used structural steels are: [1]
Carbon steels
- A36 - structural shapes and plate
- A53 - structural pipe and tubing
- A500 - structural pipe and tubing
- A501 - structural pipe and tubing
- A529 - structural shapes and plates
High strength low alloy steels
- A441 - structural shapes and plates
- A572 - structural shapes and plates
- A618 - structural pipe and tubing
- A992 - W shapes beams only
Corrosion resistant high strength low alloy steels
- A242 - structural shapes and plates
- A588 aka Cor-ten - structural shapes and plates
Quenched and tempered alloy steels
Steel vs. A36 steel is a standard Steel alloy which is a common structural steel used in the United States ASTM A53 is a carbon Steel Alloy, used for Structural steel pipe ASTM A500 is a standard specification published by the ASTM for cold-formed welded and seamless carbon steel structural tubing in round square and rectangular shapes ASTM A500 is a standard specification published by the ASTM for cold-formed welded and seamless carbon steel structural tubing in round square and rectangular shapes Weathering steel, best-known under the trademark COR-TEN steel is a group of Steel alloys which were developed to obviate the need for painting and form a stable Weathering steel, best-known under the trademark COR-TEN steel is a group of Steel alloys which were developed to obviate the need for painting and form a stable A514 is a particular type of high strength Steel, which is Quenched and Tempered Alloy steel with basic strength of 100000 psi (100 A514 is a particular type of high strength Steel, which is Quenched and Tempered Alloy steel with basic strength of 100000 psi (100 concrete
As raw material prices fluctuate, often so does building design. During times of lower steel prices, more steel and less concrete is used, and vice versa. Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag Each set of vendors and users typically maintain national industry associations that advocate the use of its materials versus the other. However, both materials are typically used together. Concrete without steel reinforcement (usually ribbed round bars called Rebar) crumbles under tensile loads. A rebar, or reinforcing bar, is a common Steel bar and is commonly used in Reinforced concrete and reinforced Masonry structures Steel on its own, without solid concrete floors, is likewise not a preferred building method.
While rebar is almost always steel, it is not considered a structural steel and is described separately in the Rebar and Reinforced concrete articles. A rebar, or reinforcing bar, is a common Steel bar and is commonly used in Reinforced concrete and reinforced Masonry structures Reinforced concrete is Concrete in which reinforcement bars (" Rebars quot or fibers have been incorporated to strengthen a material that would otherwise be
Thermal properties
The properties of steel vary widely, depending on its alloying elements.
The austenizing temperature, the temperature where a steel transforms to an austenite crystal structure, for steel starts at 900°C for pure iron, then, as more carbon is added, the temperature falls to a minimum 724°C for eutectic steel (steel with only . Austenite (or gamma phase iron is a metallic non-magnetic solid solution of Iron and an Alloying element 83% by weight of carbon in it). As 2. 1% carbon (by mass) is approached, the austenizing temperature climbs back up, to 1130°C. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object Similarly, the melting point of steel changes based on the alloy.
The lowest temperature at which a plain carbon steel can begin to melt, its solidus, is 1130 °C. Steel never turns into a liquid below this temperature. Pure Iron ('Steel' with 0% Carbon) starts to melt at 1492 °C (2720 °F), and is completely liquid upon reaching 1539 °C (2802 °F). Steel with 2. 1% Carbon by weight begins melting at 1130 °C (2066 °F), and is completely molten upon reaching 1315 °C (2400 °F). 'Steel' with more than 2. 1% Carbon is no longer Steel, but is known as Cast iron. Cast iron usually refers to grey cast iron, but identifies a large group of Ferrous Alloys which solidify with a Eutectic. http://www.msm.cam.ac.uk/phase-trans/images/FeC.gif
Fireproofing of structural steel
In order for a fireproofing product to qualify for a certification listing of structural steel, through a fire test, the critical temperature is set by the national standard, which governs the test. "Fireproof" redirects here For the album see Fireproof (album. A Certification listing is a document against which a field installation is compared to make sure that it complies with a regulation such as a Building code. A fire test is a means of determining whether or not Fire protection products meet minimum performance criteria as set out in a Building code or other applicable legislation In Japan, this is below 400°C. For a topic outline on this subject see List of basic Japan topics. In China, Europe and North America, it is set at ca. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National 540°C. The time it takes for the steel element that is being tested to reach the temperature set by the national standard determines the duration of the fire-resistance rating. A fire-resistance rating typically means the duration for which a Passive fire protection System can withstand a standard fire resistance test.
Care must be taken to ensure that thermal expansion of structural elements does not damage fire-resistance rated wall and floor assemblies. Thermal Expansion is the tendency of matter to change in Volume in response to a change in temperature A fire-resistance rating typically means the duration for which a Passive fire protection System can withstand a standard fire resistance test. Penetrants in a firewalls and ferrous cable trays in organic firestops should be installed in accordance with an appropriate certification listing that complies with the local building code. In Construction, a firewall is a fire-resistance rated Wall assembly intended to slow the A cable tray system according to the US National Electrical Code is "a unit or assembly of units or sections and associated fittings forming a rigid structural system used to A firestop is a Passive fire protection System of various components used to seal openings and joints in fire-resistance rated wall A Certification listing is a document against which a field installation is compared to make sure that it complies with a regulation such as a Building code. A building code, or building control, is a set of rules that specify the minimum acceptable level of safety for constructed objects such as Buildings and Nonbuilding
Open Web Steel Joists (OWSJ) require a great deal of spray fireproofing because they are not very massive and also because they are so open, that a lot of the sprayed plaster flies right past its constituent parts during the coating process. The term plaster can refer to plaster of Paris Lime plaster, or Cement plaster.
Structural steel requires external insulation (fireproofing) in order to prevent the steel from weakening in the event of a fire. When heated, steel expands and softens, eventually losing its structural integrity. Given enough energy, it can also melt. Heat transfer to the steel can be slowed by the use of fireproofing materials. "Fireproof" redirects here For the album see Fireproof (album. While concrete structures that comprise buildings are able to achieve fire-resistance ratings with out additional fireproofing, concrete can be subject to severe spalling, particularly if it has an elevated moisture content. Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag Fireproofing is available for concrete but this is typically not used in buildings. Instead, it is used in traffic tunnels and locations where a hydrocarbon fire is likely to break out. In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon. Thus, steel and concrete compete against one another not only on the basis of the price per unit of mass but also on the basis of the pricing for the fireproofing that must be added in order to satisfy the passive fire protection requirements that are mandated through building codes. Passive fire protection (PFP is an integral component of the three components of structural Fire protection and fire safety in a Building. A building code, or building control, is a set of rules that specify the minimum acceptable level of safety for constructed objects such as Buildings and Nonbuilding Common fireproofing methods for structural steel include intumescent, endothermic and plaster coatings as well as drywall and calcium silicate cladding. An intumescent is a substance which swells as a result of Heat exposure thus increasing in Volume, and decreasing in Density. In Thermodynamics, the word endothermic "within-heating" describes a process or reaction that absorbs Energy in the form of Heat. The term plaster can refer to plaster of Paris Lime plaster, or Cement plaster. For the musical group "Drywall" see Drywall (musical project Drywall is a common manufactured Building material Calcium silicates are a set of four compounds obtained by reacting Calcium oxide and silica in various ratios
See also
References
- ^ Manual of Steel Construction, 8th Edition, 2nd revised printing, American Institute of Steel Construction, 1987, ch 1 page 1-5
External links
- The American Institute of Steel Construction, Inc.
- Product Data Standards for Structural Steel (CIS/2, IFC) The product data standards facilitate interoperability between CAD software
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