Structural shapes, steels

The Standard covers bar, plates, sheets, strip, structural shapes rolled stock, pipes, sheets with laminar coating and strip of carbon, alloyed and electrical steels and sets up nondestructive magnetic method of mechanical and service properties and microstructure control. 

Available forms Structural shapes of all types, plates, rods, wire foil flakes, powder (technical and USP). Aluminum can be electrolytically coated and dyed by the anodizing process (see anodic coating) it can be foamed by incorporating zirconium hydride in molten aluminum, and it is often alloyed with other metals or mechanically combined (fused or bonded) with boron and sapphire fibers or whiskers. Strengths up to 55,000 psi at 500C have been obtained in such composites. A vapor-deposition technique is used to form a tightly adherent coating from 0.2 to 1 mil thick on titanium and steel. 

Properties. The properties of plain carbon steels are governed principally by carbon content and microstructure. These properties can be controlled by heat treatment as discussed. About half the plain carbon steels are used in the hot-rolled form, although increasingly the property combinations are enhanced by controlled cooling following the last stand of the hot mill for structural shapes, sheet, and strip. The other half are cold-rolled to thin sheet or strip and used direcdy or with an annealing treatment such as described. 

Fig. 27. U.S. shipments of steel mill products, where (— —) represents bars-reinforcing, (—0—) hot-rolled and cold-finished bars, (—ce—) tinplate, (— —) sheet-cold-rolled, (—0—) structural shapes, (— —) plate, (— —) sheet-hot-rolled, and (—a—) sheet-coated products.

Zhang Y.F., Zhang D.F., Zhao J.H. 2013. Experimental study on seismic behavior of connection between composite CFST column and H-shaped steel beam. Journal of Building Structures 34(9) 40-48 (in Chinese). 

A 709, grade 50 and 50W Structural steel V, Nb, N, Cr, Ni, Mo All structural-shape groups and plate <100 mm in thickness Minimum yield strength of 345 MPa, Grade 50W is a weathering steel Bridges... 

HSLA steels usually require 25 to 30% more energy than do structural carbon steels. Commercially HSLA steels are available in all standard wrought forms (i.e., sheet, strip, plate, structural shapes, bar-size shapes, and special shapes). 

As with the structural shapes of first-generation profiles (see Section 9.8.1), which mimic the geometry of structural steel cross-sections, so the current practice of bolting FRP structural elements copies the constructive details of steel construction (Fig. 9.4). In most cases, this direct knowledge transfer of connection technology leads to oversized FRP components, since it does not consider the different behavioms of the two materials. In fact, the linear-elastic behaviour of FRP profiles is incompatible with plastic deformations and so the stress concentrations aronnd the bolt holes are higher than those... 

Until quite recently, the structural shapes of pultruded profiles have been copied from steel construction, usually reproducing thin-walled open (I, H, L, C) or tubular (square, rectangular, circular) cross-sections. Figure 9.8 shows the most typical shapes of the so-called first-generation profiles, which are normally composed of glass fibres embedded in polyester or vinylester based resin matrix - GFRP pultruded profiles. 

FRP structural shapes are very light in weight, which permits them to be easily transported, handled, and set into place. They weigh 80% less than a corresponding steel shape and 30% less than a corresponding aluminum shape. 

As noted earlier, the riser is an important component of an offshore structure. For a floating structure there are a variety of risers in use today, which are schematically identified in Fig. 24.14. The vertical risers are still the most common and always used for the drilling operation. These risers for drilling and production operation are pretensioned (Top Tension Risers, TTR). The production risers may have a catenary shape (Steel Catenary Riser, SCR) or may be flexible as well. Flexible risers may have additional buoyancy elements giving it an S-shape. 

Standard structural shapes, including pipe, which makes an excellent structural shape, can be used. Electrodes such as the E6OIO-II types are often the welder s first choice for this kind of fabrication welding because of their all-position characteristics. These electrodes, which are not low-hydrogen types, may be used providing the weldability of the steel is such that neither weld cracks nor severe porosity is likely to occur. 

Prior to appbcation of corrosion inhibiting or insulating wrapping tapes to structural steel, the steel should be thoroughly cleaned and primed, tubular structures wrapped, and structural shapes taped longitudinally. The tape should be well pressed down and smooth, and the tension should not be excessive. Folds and air pockets should be avoided the tape over protruding nuts, bolts, etc., should be cut in the form of cross, with the tape pressed firmly to the metal and the exposed surface patched up with a piece of tape (see Figure 10.20). 

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