Francis D. K Ching Building Construction Illustrated This is an excellent text to use during this term. Chapter 4 pages 4.14-4.22 are very imformative when dealing with structural steel. Please review

this information for now and future reference. Structural steel detailing is a career that students can get into. Answer the following questions and submit to Canvas for grading. 1. How is the base of a steel column mounted? 2. What is a girder in steel framming? (google) 3. What is a beam in steel framming? (google) 4. What is a moment connection used for? 5. What is a shear connection used for? 6. How are open web steel joist supported on the ends? 7. How is the spacing between steel joist determined? 8. What is the minimum length for 8K1 Series Joist, 18LH5 and DH longest span? 9. What is the purpose of a seat angle? 10. What is the term for when the top of a beam is cut away to make it flush with another beam?/n 4.14 STRUCTURAL STEEL FRAMING Structural steel girders, beams, and columns are used to construct a skeleton frame for structures ranging in size from one-story buildings to skyscrapers. Because structural steel is difficult to work on-site, it is normally cut, shaped, and drilled in a fabrication shop according to design specifications; this can result in relatively fast, precise construction of a structural frame. Structural steel may be left exposed in unprotected noncombustible construction, but because steel can lose strength rapidly in a fire, fire-rated assemblies or coatings are required to qualify as fire-resistive construction. In exposed conditions, corrosion resistance is also required. See 12.08 for a discussion of steel as a construction material; see the Appendix for fire-rated steel assemblies. . Steel framing is most efficient when the girder and beam supports are laid out along a regular grid. Resistance to lateral wind or earthquake forces requires the use of shear walls, diagonal bracing, or rigid framing with moment-resisting connections. For nonbearing or curtain wall options, see 7.24. . Metal floor deck w/ concrete fill; see 4.22- Steel beam- Steel girder- . Connections usually use transitional elements, such as steel angles, tees, or plates. The actual connections may be riveted but are more often bolted or welded. When bearing on concrete or masonry, steel bearing plates are required to distribute the concentrated load imposed by a column or beam so that the resultant unit bearing pressure does not exceed the allowable unit stress for the supporting material. CSI MasterFormat 05 12 00: Structural Steel Framing H H H H H H H H STRUCTURAL STEEL FRAMING 4.15 • Lateral-load-carrying mechanisms are required in both directions, but lateral forces tend to be more critical in the short direction. • Each pair of external columns supports a long-spanning beam or girder. This system is suitable for long, narrow buildings, especially when a column-free space is desired. One-Way Beam System Girder Beams Typical span range for beams is 20' to 32' (6 to 10 m); above this range, open- web steel joists become an economical alternative due to their reduced weight. Beams are spaced 6' to 15' (1830 to 4570), depending on the magnitude of the applied load and spanning capability of the floor deck. Steel framing should utilize rectangular bay units, with comparatively lightly loaded beams spanning farther than more heavily loaded girders. Two-Way Beam System Framing beams into girders minimizes floor depth; some mechanical services can pass through holes cut into the beam webs, but large lines may have to be accommodated in a suspended ceiling space below. Two-layer system increases floor depth considerably but provides more space for mechanical services. ⚫ Girders spanning the short axis of a building can contribute to the lateral stability of the structure. Primary beams- Secondary beams- • When a large, column-free space is required, long-spanning plate girders or trusses can be used to carry the primary beam, which in turn support a layer of secondary beams, ⚫ Long-spanning members Triple Beam System 4.16 STEEL BEAMS S shape W shape More structurally efficient wide-flange (W) shapes have largely superseded the classic I-beam (S) shapes. Beams may also be in the form of channel (C) sections, structural tubing, or composite sections. Rules of thumb for estimating depth: beams: span/20 girders: span/15 Width=1/3 to 1/2 of depth The general objective is to use the lightest steel section that will resist bending and shear forces within allowable limits of stress and without excessive deflection for intended use. • In addition to material costs, also consider the labor costs required for erection. . C shape Structural tubing ITH wwwwww I Plate girders are built up from plates or shapes that are welded or riveted together. A web plate forms the web of a plate girder, while flange angles form the top and bottom flanges. Shear plates may be fastened to the web of the girder to increase its resistance to shearing stresses. Cover plates are fastened to the flanges of a plate girder to increase its section modulus in areas subject to high bending stresses. Stiffener angles are fastened to each side of a web plate to stiffen it against buckling; bearing stiffeners are placed at a point of support or under a concentrated load; intermediate stiffeners are placed between bearing stiffeners for increased resistance to diagonal compressive stresses. Box girders are built up from shapes and have a hollow, rectangular cross section. Castellated beams are fabricated by dividing the web of a wide-flange section with a lengthwise zigzag cut, then welding both halves together at the peaks, thus increasing its depth without increasing its weight. CSI MasterFormat 05 12 23: Structural Steel for Buildings There are many ways in which steel connections can be made, using different types of connectors and various combinations of bolts and welds. Refer to the American Institute of Steel Construction's (AISC's) Manual of Steel Construction for steel section properties and dimensions, allowable load tables for beams and columns, and requirements for bolted and welded connections. In addition to strength and degree of rigidity, connections should be evaluated for economy of fabrication and erection, and for visual appearance if the structure is exposed to view. The strength of a connection depends on the sizes of the members and the connecting tees, angles, or plates, as well as the configuration of bolts or welds used. The AISC defines three types of steel framing that govern the sizes of members and the methods for their connections: moment connections, shear connections, and semi-rigid connections. . . STEEL BEAM CONNECTIONS 4.17 Stiffener plates welded to column Top and bottom flanges welded to column Tab plate welded to column and bolted to beam web Weld flanges or use a splice plate bolted to top flanges of girder and beam. Beam welded to stiffener plates and bolted to tab- Shear bolts Backing bar Stiffener Stiffener plates welded to column and bolted to beam flanges Welded all around Shear tab welded to column and bolted to . Girder- Shear is carried by plates welded to girder web and bolted to beam web. Plate welded to girder web and bolted to bottom flange of beam Welded web stiffeners beam web- Moment Connections Erection seat angle AISC Type 1-Rigid Frame-connections are able to hold their original angle under loading by developing a specified resisting moment, usually by means of plates welded or bolted to the beam flanges and the supporting column. Beam continues over girder; bolt to keep beam from shifting. Small openings may be cut or drilled in web; large openings weaken web in shear and require stiffening or reinforcement. 4.18 STEEL BEAM CONNECTIONS • A framed connection is a shear-resisting steel connection made by welding or bolting the web of a beam to the supporting column or girder with two angles or a single tab plate. Two angles welded or bolted to column and web- of beam Stabilizing angle • A seated connection is a shear-resisting steel connection made by welding or bolting the flanges of a beam to the supporting column with a seat angle below and a stabilizing angle above. Seat angle carries shear load. Tab plate welded to column and bolted to web of beam • A seated connection may be stiffened to resist large beam reactions, usually by means of a vertical plate or pair of angles directly below the horizontal component of the seat angle. I Angles bolted or welded to webs of girder and beam; for the top of the beam to be flush w/ the top of the girder, the top flange of the beam is coped or cut away. Two angles shop-welded to beam web and field-welded to column Bolts hold beam in place until welds are made on site. Shear Connections AISC Type 2-Simple Frame-connections are made to resist only shear and are free to rotate under gravity loads. Shear walls or diagonal bracing is required for lateral stability of the structure. End plate welded to beam all around and bolted to column • All-welded connections are aesthetically pleasing, especially when ground smooth, but they can be very expensive to fabricate. Semi-Rigid Connections AISC Type 3-Semi-Rigid Frame-connections assume beam and girder connections possess a limited but known moment-resisting capacity.