We use steel as the structure in many kind of construction work such as Factory, Nuclear Support Structures and other world trade centers. Steel are produced in many kind of section or shapes that suitable and cost saving with the function of structure that stand for long life. Those shapes are M shape, W shapes, C shapes, Hollow structural section (HSS), and Many others as shown in figure below: I. Kinds of steel A. Carbon steel More than 90 percent of all steels are carbon steels. They contain varying amounts of carbon and not more than 1.65 percent manganese, 0.60 percent silicon, and 0.60 percent copper. Machines, automobile bodies, most structural steel for buildings, ship hulls, bed-springs, and bobby pins are among the products made of carbon steels. B. Alloys steel These steels have a specified composition, containing certain percentages of vanadium, molybdenum, or other elements, as well as larger amounts of manganese, silicon, and copper than do the regular carbon steels. Automobile gears and axles, roller skates, and carving knives are some of the many things that are made of alloy steels. C. High-strength low alloy steel Called HSLA steels, they are the newest of the five chief families of steels. They cost less than the regular alloy steels because they contain only small amounts of the expensive alloying elements. They have been specially processed, however, to have much more strength than carbon steels of the same weight. For example, freight cars made of HSLA steels can carry larger loads because their walls are thinner than would be necessary with carbon steel of equal strength; also, because an HSLA freight car is lighter in weight than the ordinary car, it is less of a load for the locomotive to pull. Numerous buildings are now being constructed with frameworks of HSLA steels. Girders can be made thinner without sacrificing their strength, and additional space is left for offices and apartments. D. Strainless steel Stainless steels contain chromium, nickel, and other alloying elements that keep them bright and rust resistant in spite of moisture or the action of corrosive acids and gases. Some stainless steels are very hard; some have unusual strength and will retain that strength for long periods at extremely high and low temperatures. Because of their shining surfaces architects often use them for decorative purposes. Stainless steels are used for the pipes and tanks of petroleum refineries and chemical plants, for jet planes, and for space capsules. Surgical instruments and equipment are made from these steels, and they are also used to patch or replace broken bones because the steels can withstand the action of body fluids. In kitchens and in plants where food is prepared, handling equipment is often made of stainless steel because it does not taint the food and can be easily cleaned. E. Tool steel These steels are fabricated into many types of tools or into the cutting and shaping parts of power-driven machinery for various manufacturing operations. They contain tungsten, molybdenum, and other alloying elements that give them extra strength, hardness, and resistance to wear. II. Steel as Bridge structure
Bridge
(structure), structure designed to provide continuous passage over an
obstacle. Bridges commonly carry highways, railroad lines, and pathways over
obstacles such as waterways, deep valleys, and other transportation routes.
Bridges may also carry water, support power cables, or house telecommunications
lines.
A bridge must be strong enough to support its own weight
as well as the weight of the vehicles and people that use it. It must also be
able to resist varying environmental conditions. Different designs serve
different purposes and lengths of spans. Load is transferred by hangers (arch
bridges) or cables (suspension and cable-stayed bridges) to towers or abutments
at the ends of the bridge, and these in turn transfer the force into the ground.
Cantilever bridges have two independent cantilever arms projecting toward each
other and joined by a central span.
Bridge designs differ in the way they support loads. These loads include the weight of the bridges themselves, the weight of the material used to build the bridges, and the weight and stresses of the vehicles crossing them. There are basically eight common bridge designs: beam, cantilever, arch, truss, suspension, cable-stayed, movable, and floating bridges. Combination bridges may incorporate two or more of the above designs into a bridge. Each design differs in appearance, construction methods and materials used, and overall expense. Some designs are better for long spans. Beam bridges typically span the shortest distances, while suspension and cable-stayed bridges span the greatest distances. 1. Beam bridgeBeam bridges represent the simplest of all bridge designs. A beam bridge consists of a rigid horizontal member called a beam that is supported at both ends, either by a natural land structure, such as the banks of a river, or by vertical posts called piers. Beam bridges are the most commonly used bridges in highway construction. Single-piece, rolled-steel beams can support spans of 15 to 30 m (50 to 100 ft). Heavier, reinforced beams and girders are used for longer spans.
 4. Truss Bridge
Reference 1. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. (Software)  |
