1. Chapter 7
Metals

2. Objectives
After reading the chapter and reviewing the materials presented the students will be able to:
Outline the basic steps for erecting a steel structure.
Identify common types of nails, bolts, and screws.
Identify products commonly used in construction.

3. Introduction
Ferrous metals contain a large percentage of iron. Steel is an example of a ferrous metal. They are magnetic.
Nonferrous metals contain little or no iron. Copper and aluminum are nonferrous metals. They are not magnetic.
Combining metals with other elements forms alloys. Steel is an alloy of iron and carbon. Brass is an alloy of copper and zinc.

4. Steel: Manufacturing Processes
Casting is done by pouring molten steel into moulds or by continuous casting.
Casting moulds are made from a sand and clay mixture that can be easily removed once the steel solidifies.
Continuous casting produces a ribbon of semi finished steel that is shaped into sheets, structural shapes, and bars.
Extrusion produces shapes of uniform cross section by forcing steel through dies of appropriate shape. Tubing, pipe, and bars can be extruded in a variety of shapes and sizes.
Forging involves pressing or stamping preheated steel between dies of the desired shape. Forging is used to make tools, brackets, clamps, and some fasteners.
Drawing involves pulling steel through a series of dies to produce a desired cross sectional shape. Drawing is primarily used to make wire.

5. Structural Steel and Bar Stock
Structural steel is construction material that has specific properties and is formed into cross sections, or shapes.
It is often used for framing on buildings and other structures.
Bar stock is raw material that comes in many of the same shapes as structural steel, but in smaller sizes (fig 7-7, page 127).
Bar joists are made from bar stock and are often used for framing, and may be used to frame floors.
Typical Uses: A basic building frame is composed of columns, girders, and beams.
Columns provide vertical support. I beams and wide flange I beams are typically used for columns.
Girders are large horizontal structural members that are supported by columns.
Beams are horizontal structural members that are supported by girders.

6. Joining Techniques
Traditionally, structural steel was joined using rivets.
Today, high strength structural bolts and welding are more common.
Erecting Steel Structures:
Each component of a steel framed structure is made in a steel fabrication shop.
Brackets are welded in place and holes are drilled for bolts or rivets.
Columns are put in place first.
The base plate, welded to the bottom end of columns, fits over anchor bolts that were cast in the foundation. Columns must be plumb (vertical).
Girders are then attached to the columns and beams are connected to the girders (fig 7-13, page 131).The sides of girders and beams also need to be plumb.
Hand signals and two radio communication enable the ironworkers to communicate with the crane operator.
A hand operated winch, called a come-along, is used to pull the steel in position (figure 7-13).
Bracing involves installing diagonal steel components to make the frame rigid.
Once the frame is permanently fastened with bolts, rivets, or welding, the guy wires are removed.

7. Reinforcing Steel
Concrete is often reinforced with steel to give the concrete additional tensile strength.
Rebar is used in footings, walls, columns, floors, sidewalks, and paving.
Welded wire mesh may replace the rebar in floors, sidewalks, and paving.
High tensile strength steel (HTSS) cable is most often used in concrete beams, floor panels, and other products that are manufactured off site.

8. Steel Plate and Sheet Steel
Flat slabs of steel that are 1/8” and thicker are called steel plate.
Sheet steel is less than 1/8” thick.
Sheet steel that is specially coated may be used for decking under concrete floors, siding, or roofing.
Heating and air conditioning ducts are often made from galvanized sheet steel. Galvanizing is a process in which steel is coated with zinc to prevent rusting.

9. Steel Pipe and Tubing
Most steel pipe and steel tubing is produced using an electric welding process.
Steel tubing used for structural components is cleaned and coated with a primer.
Black iron pipe and fittings are used for compressed air and fuel gas piping.
Steel pipe is joined using threaded fittings that are tapered. This makes the joint watertight.

10. Light Gage Steel Framing Members
Light gage steel framing members have long been used for interior wall studs in commercial buildings.
Metal framing tends to be less expensive than wood framing.
Disadvantage is metal studs in exterior walls increases heat flow, reducing the insulating value of the exterior wall.

11. Framing Connectors
Framing connectors are designed to increase the strength of connections.
They are made of galvanized steel and are prepunched for fasteners.
Strapping connectors, also called ties hold parts of a frame together. They are often required by building codes in earthquake zones and areas where high wind speeds are a concern.
Hanging connectors connect the end of one framing member to the side of another.
Both strapping and hanging connectors are attached with nails or screws.
Corrosion resistant fasteners are required for exterior applications.

12. Fasteners
Nails, bolts, and screws are the most commonly used fasteners in construction.
In the late 1800’s, a machine was invented that made nails from wire. Roofing nails have large heads to prevent them from pulling through shingles. In construction today, most nails are driven with nail guns.
Bolts are inserted through holes drilled in the materials to be fastened. They are secured using nuts that thread onto the bolt. Anchor bolts are embedded in concrete foundations. The hook or twist on the embedded end of the anchor bolt prevents the bolt from pulling out of cured concrete.
One advantage of screws over nails is that they can be removed without damaging the components being fastened. Common types of screwdriver shapes are slotted, Phillips, square, and combination drive (fig 7-33, page 141).

13. Working with Fasteners
Finish nails are set below the board surface with a nail set. Setting permits the nail head to be covered by putty so it is not visible (fig 7-37, page 142).
Screw installation often requires that a clearance hole be drilled through the top piece of the material and a pilot hole be drilled into the bottom piece of the material. A clearance hole allows the screw to be driven without splitting the wood and reduces the force required to drive the screw.

14. Aluminum and Copper
Neither aluminum or copper rust (nonferrous metals), so they are commonly used where rust resistance is important.
Aluminum sheet is formed into gutters, downspouts, siding, flashing, and roofing.
Aluminum extrusions are used to make window and door frames.
Copper sheets are formed into gutters, downspouts, flashing, and roofing.
Most electrical wire is made from copper.
Copper pipe and fittings are widely used for plumbing.

15. Summary
Ferrous metals contain a large percentage of iron. Steel is an example of a ferrous metal. They are magnetic.
Combining metals with other elements forms alloys. Steel is an alloy of iron and carbon.
Casting is done by pouring molten steel into moulds or by continuous casting.
Extrusion produces shapes of uniform cross section by forcing steel through dies of appropriate shape. Tubing, pipe, and bars can be extruded in a variety of shapes and sizes.
Forging involves pressing or stamping preheated steel between dies of the desired shape. Forging is used to make tools, brackets, clamps, and some fasteners.
Drawing involves pulling steel through a series of dies to produce a desired cross sectional shape. Drawing is primarily used to make wire.
Structural steel is construction material that has specific properties and is formed into cross sections, or shapes.
Columns provide vertical support. I beams and wide flange I beams are typically used for columns.
Girders are large horizontal structural members that are supported by columns.
Beams are horizontal structural members that are supported by girders.
A hand operated winch, called a come-along, is used to pull the steel in position.
Bracing involves installing diagonal steel components to make the frame rigid.
Galvanizing is a process in which steel is coated with zinc to prevent rusting.
Steel tubing used for structural components is cleaned and coated with a primer.
Black iron pipe and fittings are used for compressed air and fuel gas piping.
Light gage steel framing members have long been used for interior wall studs in commercial buildings.
Nails, bolts, and screws are the most commonly used fasteners in construction.
Aluminum sheet is formed into gutters, downspouts, siding, flashing, and roofing.
Most electrical wire is made from copper.

16. Home Work
1.What type of metals contain iron? Give an example. What is one property of metals that contain iron?
2. How are columns, girders, and beams used in erecting steel structures?