1. Class Day Sixteen

2. Steel Frame Construction
Chapter 11
Steel Frame Construction

3. HISTORY OF IRON AND STEEL
Iron is a natural element found in the earth and has been known to man for thousands of years.
Iron ore is mined from the earth and heated to a very high temperature using fuel with a blast of air to remove impurities. It is then cast into forms called “pigs” to be re-developed into other products such as cast iron, wrought iron, and steel.
“Any range of alloys or iron with less than 2% carbon”
Carbon content
TOO MUCH CARBON - HARD, BUT BRITTLE
EX - CAST IRON IS 3-4% CARBON
TOO LITTLE - SOFT & WEAK
OPTIMAL - <.3% CARBON (MILD STEEL)
Strength
Yield strength
DEFORMS - DOES NOT RETURMN TO ORGINAL CONFIGURATION
PSI
POUNDS per SQUARE INCH
36,000psi to 65,000psi +

4. CAST IRON, is formed by remelting pig iron in a furnace and pouring it into molds to make castings. It contains from 2% to 6% carbon, and scrap iron or steel is often added to vary the composition. Cast iron is used extensively to make machine parts, engine cylinder blocks, stoves, pipes, radiators, and many other products.
Cast Iron was the early form of usable ferrous metal made from iron ore. The high content of carbon makes it hard and brittle.
First structures of cast iron were built in the late 1700s
Cast Iron is brittle, difficult to work with, cannot be welded, and is difficult to shape, except in molds.

5. WROUGHT IRON is purified iron
WROUGHT IRON is purified iron. Pig iron is refined in a Bessemer converter and then poured into molten iron-silicate slag. The resulting semisolid mass is passed between rollers that squeeze out most of the slag.
Wrought iron is tough, malleable, ductile, and corrosion-resistant, and melts only at high temperature.
In early days it was used as a structural material for framework, but with the development of steel, wrought iron has widespread use to make ornamental ironwork.

6. The most famous structure built with wrought iron is the Eiffel Tower in Paris, France.
Built entirely of wrought iron, it contains 18,000 pieces of iron and 2,500,000 rivets to connect them.

7. The Eiffel Tower, Paris France
3/15/1888
9/14/1888
12/26/1888
3/12/1889
Construction time- Foundation - 5mo, Tower 21mo.

8. STEEL is an alloy of iron, carbon, and small proportions of other elements. Steelmaking involves the removal of iron's impurities and the addition of desirable alloying elements to provide a specific material.
Steel was not produced economically until the development of the Bessemer furnace in the 1850s. The process involved blasting air through a tube to the bottom of molten iron ore to remove impurities.
Steel is often classified by its carbon content. A high-carbon steel is hard and brittle. Low- or medium-carbon steel can be welded and tooled.

9. Alloy steels, now the most common, contain one or more elements that give them special properties. Aluminum steel is smooth and has a high tensile strength. Chromium steel is used in automobile and airplane parts because of its hardness, strength, and elasticity.
Nickel steel is the most widely used of the alloys. It is nonmagnetic and has the tensile properties of high-carbon steel without the brittleness. Stainless steel has a high tensile strength and resists abrasion and corrosion because of its high chromium content.
Nickel is added to make stainless steel. Chromium is added to make decorative, highly polished steel. A tenacious oxide coating can be given to steel to form a protective coating of rust, called “weathering steel.”

10. ADVANTAGES OF STEEL AS A BUILDING MATERIAL
Light in proportion to its strength
Strong & Stiff in proportion to its weight
Fabrication is done in controlled conditions
Steel is quick to erect
It is a precise & predictable material
Steel is 100% Recyclable – by far the largest percentage
of new steel produced in America is
recycling scraps.

11. DISADVANTAGES OF STEEL
It will deteriorate due to rust if not protected.
Prolonged exposure to high temperature fires will substantially weaken its structural characteristics. Even though steel does not burn, framework in buildings must be protected from intense heat.

12. STEEL SHAPES FOR CONSTRUCTION
Standard Steel shapes offer a variety for use as beams, columns, and special structural applications
Wide Flange Shapes
American Standard – The “I” beam.
Channels
Angles – equal leg and unequal leg
Structural Tubing – square, rectangular, and round.
Plate
Square and round bars
Special shapes that may be made from standard shapes, such as Tees cut from wide flange shapes.

13. A WIDE FLANGE SHAPE is so called because the flanges at top and bottom are a width similar to the depth of the beam.
The first shapes of the type were called Standard Shapes and the width of the flanges was narrow in comparison.
But structural techniques proved that a beam with a wider flange has a greater load carrying capacity and resistance to deflection.
Size Range
Depth; 4” to 36”
Weight; 9#/ft to 730#/ft
Uses - Beams & Columns
Proportions - Shape
Tall &Narrow - Beams
Square - Columns & Piles

14. All steel today is manufactured under extreme controlled conditions according to specifications of the American Society for Testing and Materials.
Two basic formulas for steel for general construction is manufactured according to its strength. ASTM A-36 steel is the standard, with a yield strength of 36,000 p.s.i. ASTM A-50 steel is available for higher strength projects such as multistory buildings, and has a yield strength of 50,000 p.s.i.
Steel structural design, fabrication, and erection is done according to the specifications of the Manual of Steel Construction published by the American Institute of Steel Construction.

15. The following exhibits are sample pages from the Manual of Steel Construction that represent standard shapes and sizes of various structural members available to designers of steel frames.
The first are called “W” shapes a designation shortened from the previous name, “Wide Flange”
The tables a variety of sizes and the physical characteristics of each that are needed to establish structural calculations and details.
W indicates the shape of the cross section, the first number indicates the nominal depth of the member, and the second number indicates the weight per lineal foot.

16. A Wide Flange section is designated by W, the nominal depth, and weight per foot. The first Section in the chart below is W 18 x 119, meaning it is a wide flange shape, its depth is 18 inches and weighs 119 pounds per foot.

17. The next example is called a “Channel” shape, of which are American Standard Channels, which are manufactured in standard shapes by all steel manufacturers. There are also “miscellaneous channels” which are available, but not made by all makers of steel products.
The designation for identity is a “C”, the first number is the exact depth of the cross section, and the second number is the weight per lineal foot.

18. STANDARD CHANNELS are designated by the letter C, its depth, and weight per foot. The first section below is a C 15 x 50, meaning it is a channel, it is 15 inches deep, and it weighs 50 pounds per foot.

19. The next examples are called “Angles,” which are L – shaped members in cross section. The legs of the members may be of equal length or of unequal length.
The designation for identity is “L” followed by three numbers; the first indicating the length of the longest leg, the second the length of the short leg, followed by the thickness of the legs.
The weight of angles per foot is not a part of their designation.

20. ANGLES are available with even or uneven size legs
ANGLES are available with even or uneven size legs. Designated by the letter L, the size legs, and thickness of leg. The first angle below is an L 5 x 3 ½ x ¾”.

21. The next example is called “S shapes,” which is a member left over from earlier days when steel shapes were first made. It was commonly called an “I” beam.
S shapes are not used extensively in framework, as the shape is not nearly as efficient structurally as are “W” shapes. S shapes are commonly used for things like crane rails in warehouses and manufacturing plants.
The designation is “S” followed by two numbers which indicate the depth and weight per foot.

22. S SHAPES were formerly called American Standard
S SHAPES were formerly called American Standard. Are early beam shapes, replaced by Wide Flange shapes. S shapes are used for applications such as crane rails.
Designation is S, the depth, and weight per foot.

23. The next example is for pipe
The next example is for pipe. Steel pipe is round in cross section and there are 3 designations;
The first part of the designation is the pipe size, which is the nominal inside diameter, followed by a second part, of which there are three, each of which is an indication of the pipe wall thickness:
Standard (schedule 40)
X strong (schedule 80)
XX strong (schedule 120)
Example designations: “4” standard ; 4” X strong ; or 4” XX strong.

24. STEEL PIPE is round tubing with electrically welded seams, designated by its nominal inside diameter and its weight. Pipe comes in three weight classifications; Standard, Extra Strong, and Double Extra Strong. The 3” pipe below is designated “3” standard weight pipe.”

25. The next example is structural tubing, which may be either square or rectangular in cross section.
The designation is “TS” followed by a number that indicates the width of the longest side, then a number that indicates the width of the short side, followed by a number that indicates the thickness of the wall.
Example: TS 6” x 4” X ¼” the dimensions are exact sizes of the exterior of the member. Structural tubing members have rounded corners.

26. STRUCTURAL TUBING is available in rectangular and square cross section
STRUCTURAL TUBING is available in rectangular and square cross section. Designated by the letters TS, its cross section dimensions, and the wall thickness. The first section below is designated TS 8” x 3” x 3/8”

27. The last exhibit is for a miscellaneous shape called a “structural tee” which is a member cut from a W shape.
The basic use of structural tees are as web members of steel trusses, and are not used extensively as standard framing members, except for miscellaneous use where their shape would serve as a solution to a particular condition.

28. STRUCTURAL TEES are special shapes cut from another standard shape
STRUCTURAL TEES are special shapes cut from another standard shape. They have special uses, such as members to make steel trusses. Designation is by depth and weight per foot.

29. SEVERAL OTHER SECTIONS that may be considered as standard are listed in the AMERICAN INSTITUTE OF STEEL CONSTRUCTION manual.
Aside from the charts for standard shapes mentioned, others include
HP shapes used primarily as columns in large buildings
M shapes, for miscellaneous, are items a steel manufacturer has made for a particular single purpose, but still has demand for the unusual shapes. Miscellaneous wide flange shapes and channels are available.

30. Welding Welding of Steel Welding vs Bolting Welding
labor intensive (especially in the field)
Requires a highly skilled/certified craftsman
Verification of Installed Quality
Bolting - Quick, easy, and less labor intensive & skill required.
Not uncommon to see both
Welded fabrications in the shop
Bolted in the field
Welding
Fillet Weld
Full Penetration Weld

31. Steel Framing Connections
Simple Framing
Bolts only in web, not the flanges
Transmits only shear
not bending moment
Accomplished with
clip angles & bolts/welds
Moment Connections
Transmit shear & moment
Flanges must be connected
Bolt/Weld Flanges
May require column stiffeners
“Framed” Connections
Bolts only in web, not the flanges
Transmits only shear
Does not transmit bending moment
Shear & Moment Connections
Transmit shear & moment
Welded & Bolted Connection

32. Joist Spacing Depends on; Load Span capability of deck
OPEN WEB STEEL JOISTS are mass produced steel trusses made for a specific purpose.
Commonly called “bar Joists”, they are made according to specifications of the STEEL JOIST INSTITUTE by a variety of companies.
Common Uses
Floor Support
Roof Support
Joist Spacing Depends on;
Load
Span capability of deck
Typically 2 to 10 feet
“Mass” produced steel trusses
SERIES OF SMALL ANGLES, ROD, ETC.
Common Uses
Floor Support
Roof Support
Joist Spacing Depends on;
Load
Span capability of decking
Typically 2 to 10 feet

33. OPEN WEB STEEL JOISTS are fabricated from steel bars arranged in triangular patterns, fastened between two steel angles at top and at bottom. Steel joists are actually small trusses.

34. OPEN WEB STEEL JOISTS
Steel Joists are made in three classifications:
K series joists for general purpose use for spans up to 60 feet.
LH series joists for longer spans up to 96 feet.
DLH series joists are deep trusses for long spans up to 144 feet.
Steel joists are made according to standards of the Steel Joist Institute required for loading, span conditions, and deflection. Joists are not cut and fabricated until an order is placed for a specific project.

35. Joist used for floor support

36. Joists used for Roof Support

37. Joist “Seat”
Joist Girder

38. Larger Steel Trusses Heavier Members Can Carry Larger Loads &
Span Greater Distances
Typically are Specially Fabricated

44. Steel Decking
A sheet of steel that has been corrugated to increase its stiffness
Span capability primarily based on:
Thickness (gauge) of the sheet
Depth & spacing of the corrugations
Singular or Cellular
Cold Formed
USES - FLOORS & ROOFS
Span Capability primarily based on;
Thickness (gauge) of the sheet
Depth & spacing of the corrugations
Attachment
Mechanical fastener
Welding

45. Use of Steel Decking
It can be a permanent formwork for Concrete, for floors and roofs, or for roofs where insulation and roofing membrane are placed.

46. STEEL DECKING FOR ROOFS

47. Structural Steel Fireproofing
Encasement with a fire resistant material
Concrete or Masonry
Adds dead weight
Plaster
Costly/labor intensive
Exterior or humid applications
Drywall
Also serves as finish material
Spray-on Fireproofing
Combination
Intumescent Mastics & Paints
Encasement in Concrete or Masonry
IMPROVES STRUCTURAL CAPACITY &
FIREPROOFS
Encasement in Plaster
LARGELY REPLACED BY DRYWALL
TIME & COST
Encasement in Drywall
CAN ALSO SUPPLY FINISH SURFACE
USED IN CONJUCTION W/ LIGHT STEEL FRAMING
Spray-on Fireproofing Mixture
Cementious or fiber& binder mixture
Sprayed to the required thickness
Greater thickness = greater Resistance

48. FIREPROOFING SPRAYED ON STRUCTURAL STEEL MEMBERS

49. Frank O. Gehry & Assoc. Architect “free-form curvilinear structure”
Rock -’n’- Roll Museum
Seattle
Frank O. Gehry & Assoc. Architect
“free-form curvilinear structure”
ENR 2/28/00

50. Rock -’n’- Roll Museum as seen from the Space Needle

51. Some of the ‘Exterior’ Skin of the Rock -’n’- Roll Museum