Steel Frame Construction Advantages and Disadvantages History of

Steel Frame Construction Advantages and Disadvantages

History of Iron and Steel Making n n Prior to the mid 19 th century steel a very rare and valuable commodity Development of the Bessemer Process Discovery of iron ore Today, more than 20% of all steel production is used in building construction

Iron and Steel Making n n n A refining process 1 st , iron extracted from iron ore 2 nd , carbon rich iron production 3 rd , reduce carbon content in steelmaking Add alloying elements

Foundry Production n n (small percent) Adding scrape metal reduces carbon content White cast iron Gray cast iron (graphite flakes) Malleable cast iron (annealing) Ornamental wrought iron (97% pure)

Steel Making n n n (a further refinement) Steel making process (lower the carbon content) Control impurities (residual elements) Add allowing elements Electric furnaces Open hearth furnaces Basic oxygen furnaces

Mild Structural Steel n n ASTM A 36 (predominant for decades) ASTM A 572 and A 992 (less expensive and stronger)

High Strength Low Alloy Steels

High Alloy-Stainless Steel n n n 18/8 Stainless 18% chrome 8% nickel

Steel Finishes n n n Texture Galvanizing (zinc) Aluminizing Cladding Vitreous Coatings (porcelain enamels)

Structural Steel Shapes

Open-Web Steel Joist n n K Series (span to 60 feet, depths 8 to 30 inches) LH Series (span to 96 feet, depths 18 to 48 inches) DLH Series (span 144 feet, depths 52 to 72 inches) Joist Girders

Joining Steel Members n n n Rivets Bolts Welds

Joining with Rivets

Joining with Bolts n n n n Carbon steel bolts (ASTM A 307) High-strength bolts (ASTM A 325 & A 490) Bearing connections Friction or slip-critical connections Impact wrenches Turn of the nut method Load indicator washer (visual inspection Tension control bolts

Joining with Welds n n n Types of welds The size of welds Welding symbols Backup bars and runoff bars Weld inspection

Steel Connections n n n Gusset plates and angles in use with rivets, bolts and welds Framed connections (shear, vertical bearing) Moment connections

Moment Connections (Type 1)

Coped Connection

Column Connections

Steel Framing

Stabilizing the Frame n Diagonal Bracing n Eccentric Bracing n Moment Connections n Shear Panels

n Rigid Core n Rigid Perimeter

Rigid Frames

Steel Construction Process n Fabricators

Steel Erectors

Fireproofing Steel Framing

Steel Roof Construction

Decking