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Plate Girder
A plate girder bridge is a bridge supported by two or more plate girders. Overview In a plate girder bridge, the plate girders are typically I-beams made up from separate structural steel plates (rather than rolled as a single cross-section), which are welded or, in older bridges, bolted or riveted together to form the vertical web and horizontal flanges of the beam. In some cases, the plate girders may be formed in a Z-shape rather than I-shape. The first tubular wrought iron plate girder bridge was built in 1846-47 by James Millholland for the Baltimore and Ohio Railroad. Plate girder bridges are suitable for short to medium spans and may support railroads, highways, or other traffic. Plate girders are usually prefabricated and the length limit is frequently set by the mode of transportation used to move the girder from the bridge shop to the bridge site. Generally, the depth of the girder is no less than the span, and for a given load bearing capacity, a depth of arou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trestle Bridge
A trestle bridge is a bridge composed of a number of short spans supported by closely spaced frames usually carrying a railroad line. A trestle (sometimes tressel) is a rigid frame used as a support, historically a tripod used to support a stool or a pair of isosceles triangles joined at their apices by a plank or beam such as the support structure for a trestle table. Each supporting frame is a bent. A trestle differs from a viaduct in that viaducts have towers that support much longer spans and typically have a higher elevation. Timber and iron trestles (i.e. bridges) were extensively used in the 19th century, the former making up from 1 to 3 percent of the total length of the average railroad. In the 21st century, steel and sometimes concrete trestles are commonly used to bridge particularly deep valleys, while timber trestles remain common in certain areas. Many timber trestles were built in the 19th and early 20th centuries with the expectation that they would be te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Structural Steel
Structural steel is steel used for making construction materials in a variety of shapes. Many structural steel shapes take the form of an elongated beam having a profile of a specific cross section (geometry), cross section. Structural steel shapes, sizes, chemical composition, mechanical properties such as strengths, storage practices, etc., are regulated by Technical standard, standards in most industrialized countries. Structural steel shapes, such as I-beams, have high Second moment of area, second moments of area, so can support a high Structural load, load without excessive Hogging and sagging, sagging. Structural shapes The shapes available are described in published standards worldwide, and specialist, proprietary cross sections are also available. *I-beam, I-beam (serif capital '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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reinforced Concrete
Reinforced concrete, also called ferroconcrete or ferro-concrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ductility. The reinforcement is usually, though not necessarily, steel reinforcing bars (known as rebar) and is usually embedded passively in the concrete before the concrete sets. However, post-tensioning is also employed as a technique to reinforce the concrete. In terms of volume used annually, it is one of the most common engineering materials. In corrosion engineering terms, when designed correctly, the alkalinity of the concrete protects the steel rebar from corrosion. Description Reinforcing schemes are generally designed to resist tensile stresses in particular regions of the concrete that might cause unacceptable cracking and/or structural failure. Modern reinforced concrete can contain varied reinforcing materials made o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear Stress
Shear stress (often denoted by , Greek alphabet, Greek: tau) is the component of stress (physics), stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. ''Normal stress'', on the other hand, arises from the force vector component perpendicular to the material cross section on which it acts. General shear stress The formula to calculate average shear stress or force per unit area is: \tau = ,where is the force applied and is the cross-sectional area. The area involved corresponds to the material face (geometry), face parallel to the applied force vector, i.e., with surface normal vector perpendicular to the force. Other forms Wall shear stress Wall shear stress expresses the retarding force (per unit area) from a wall in the layers of a fluid flowing next to the wall. It is defined as:\tau_w := \mu\left.\frac\_,where is the dynamic viscosity, is the flow velocity, and is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Highway
A highway is any public or private road or other public way on land. It includes not just major roads, but also other public roads and rights of way. In the United States, it is also used as an equivalent term to controlled-access highway, or a translation for ''motorway'', ''Autobahn'', ''autostrada'', ''autoroutes of France, autoroute'', etc. According to Merriam-Webster, the use of the term predates the 12th century. According to Online Etymology Dictionary, Etymonline, "high" is in the sense of "main". In North American English, North American and Australian English, major roads such as controlled-access highways or arterial (road), arterial roads are often state highways (Canada: provincial highways). Other roads may be designated "county highways" in the US and Ontario. These classifications refer to the level of government (state, provincial, county) that maintains the roadway. In British English, "highway" is primarily a legal term. Everyday use normally implies roads, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Railroad
Rail transport (also known as train transport) is a means of transport using wheeled vehicles running in railway track, tracks, which usually consist of two parallel steel railway track, rails. Rail transport is one of the two primary means of land transport, next to road transport. It is used for about 8% of passenger and rail freight transport, freight transport globally, thanks to its Energy efficiency in transport, energy efficiency and potentially high-speed rail, high speed.Rolling stock on rails generally encounters lower friction, frictional resistance than rubber-tyred road vehicles, allowing rail cars to be coupled into longer trains. Power is usually provided by Diesel locomotive, diesel or Electric locomotive, electric locomotives. While railway transport is capital intensity, capital-intensive and less flexible than road transport, it can carry heavy loads of passengers and cargo with greater energy efficiency and safety. Precursors of railways driven by human or an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baltimore And Ohio Railroad
The Baltimore and Ohio Railroad was the oldest railroads in North America, oldest railroad in the United States and the first steam engine, steam-operated common carrier. Construction of the line began in 1828, and it operated as B&O from 1830 until 1987, when it was merged into the Chessie System. Its lines are today controlled by CSX Transportation. Founded to serve merchants from Baltimore who wanted to do business with settlers crossing the Appalachian Mountains, the railroad competed with several existing and proposed Central Avenue (Albany, New York), turnpikes and canals, including the Erie Canal, Erie and Chesapeake and Ohio Canal. The railroad began operation in 1830 on a 13-mile line between Baltimore and Ellicott City, Maryland, Elliot's Mill in Maryland. Horse-drawn cars were replaced by steam locomotives the following year. Over the following decades, construction continued westward. During the American Civil War, the railroad sustained much damage but proved cru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Millholland
James Millholland (1812–1875) was an American railway master mechanic who is particularly well known for his invention of many railway mechanisms. His association with the Philadelphia and Reading Railroad Company as master machinist spanned fifty years in the early development of the American railroad. He also founded the locomotive shops at Mount Savage, Maryland, the center of the Cumberland and Pennsylvania Railroad. Millholland's inventions and contributions include the cast-iron crank axle, wooden spring, plate girder bridge, poppet throttle, anthracite firebox, water grate, drop frame, and steel tires. He was also an early user and advocate of the superheater, the feedwater heater A feedwater heater is a power plant component used to pre-heat water delivered to a steam generating boiler. Preheating the feedwater reduces the irreversibilities involved in steam generation and therefore improves the thermodynamic efficiency o ..., and the injector. Several of his in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wrought Iron
Wrought iron is an iron alloy with a very low carbon content (less than 0.05%) in contrast to that of cast iron (2.1% to 4.5%), or 0.25 for low carbon "mild" steel. Wrought iron is manufactured by heating and melting high carbon cast iron in an open charcoal or coke hearth or furnace in a process known as puddling. The high temperatures cause the excess carbon to oxidise, the iron being stirred or puddled during the process in order to achieve this. As the carbon content reduces, the melting point of the iron increases, ultimately to a level which is higher than can be achieved by the hearth, hence the wrought iron is never fully molten and many impurities remain. The primary advantage of wrought iron over cast iron is its malleability - where cast iron is too brittle to bend or shape without breaking, wrought iron is highly malleable, and much easier to bend. Wrought iron is a semi-fused mass of iron with fibrous slag inclusions (up to 2% by weight), which give it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beam (structure)
A beam is a structural element that primarily resists loads applied laterally across the beam's axis (an element designed to carry a load pushing parallel to its axis would be a strut or column). Its mode of deflection is primarily by bending, as loads produce reaction forces at the beam's support points and internal bending moments, shear, stresses, strains, and deflections. Beams are characterized by their manner of support, profile (shape of cross-section), equilibrium conditions, length, and material. Beams are traditionally descriptions of building or civil engineering structural elements, where the beams are horizontal and carry vertical loads. However, any structure may contain beams, such as automobile frames, aircraft components, machine frames, and other mechanical or structural systems. Any structural element, in any orientation, that primarily resists loads applied laterally across the element's axis is a beam. Overview Historically a beam is a squared ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flange
A flange is a protruded ridge, lip or rim (wheel), rim, either external or internal, that serves to increase shear strength, strength (as the flange of a steel beam (structure), beam such as an I-beam or a T-beam); for easy attachment/transfer of contact force with another object (as the flange on the end of a pipe (fluid conveyance), pipe, steam cylinder, etc., or on the lens mount of a camera); or for stabilizing and guiding the movements of a machine or its parts (as the inside flange of a railroad car, rail car or tram train wheel, wheel, which keep the wheels from derailment, running off the rail profile, rails). Flanges are often attached using bolts in the pattern of a bolt circle. Flanges play a pivotal role in piping systems by allowing easy access for maintenance, inspection, and modification. They provide a means to connect or disconnect Pipe (fluid conveyance), pipes and equipment without the need for welding, which simplifies installation and reduces downtime during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
