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An Introduction to Composite Steel Joists
Research and Behavior
David Samuelson, P.E. Manager for Nucor
Corporations Research and Development for
Downstream Products, Norfolk, NE Perry S. Green,
Ph.D. Technical Director Steel Joist Institute,
Myrtle Beach, SC
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History of Composite Steel Joists

• 1960s Lembeck Wang and Kaley. First
  experimental research conducted utilizing OWSJ as
  part of a composite joist system.

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History of Composite Steel Joists

• 1970s Tide and Galambos. Looked at stud shear
  connection behavior to develop composite action.

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History of Composite Steel Joists

• 1980s Leon and Curry Alsamsam. Verification
  that a composite beam model could be used to
  predict the ultimate capacity of composite steel
  joists.

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History of Composite Steel Joists
Summary of Composite Steel Joist Research
Projects University of Minnesota, Minneapolis, MN
1Test performed by Alsamsam, 1988, Curry, 1988
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University of Minnesota, Minneapolis MN
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History of Composite Steel Joists

• 1990s Patras and Azizinimini. Accurate
  predictions of ultimate load-carrying capacities
  of composite steel joists when different concrete
  strengths are used.

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History of Composite Steel Joists
Summary of Composite Steel Joist Research
Projects University of Nebraska- Lincoln, NE
2Test performed by Patras and Azizinimini, 1991
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University of Nebraska, Lincoln NE
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History of Composite Steel Joists

• 1990s-2000s Avci, Easterling, Gibbings,
  Lyons, Murray, Nguyen, Roddenberry, Sublett.
  Examination of the behavior of composite steel
  joists Ultimate strength prediction models
  Strength and behavior of stud shear connectors.

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History of Composite Steel Joists
Table 1 Summary of Composite Steel Joist
Research Projects
Summary of Composite Steel Joist Research
Projects Virginia Polytechnic Institute,
Blacksburg, VA
3Test performed by Nguyen, Gibbings, Easterling,
and Murray, 1991, Gibbings and Easterling,
1991, Gibbings, Easterling, and Murray, 1996
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Virginia Polytechnic Institute and State
University, Blacksburg VA
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Virginia Polytechnic Institute and State
University, Blacksburg VA
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Composite Joist Model
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Experimental Research

• Bottom Chord Behavior
• Top Chord Behavior
• Web Behavior
• Shear Stud Behavior

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Bottom Chord Behavior
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Top Chord Behavior
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Web Behavior
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Composite Steel Joist Design

• ?Mn minimum design flexural strength of
  composite section determined as follows.
• Mu required flexural strength determined from
  applied factored loads, kip-in. (N-mm)

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Shear Stud Behavior
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Shear Stud Layout in Strong Position
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Shear Stud Layout in Weak Position
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Shear Capacity of a Single Shear Stud
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Shear Capacity of a Single Shear Stud
Notes 1) Wr _at_ mid-height Average deck rib
width of deck rib containing the shear stud.
2) The deck is assumed to be oriented
perpendicular to the joists.
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Composite Steel Joist Components
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Summary

• A significant amount of data has been accumulated
  from testing that has been performed on composite
  steel joists over the past 40 years.
• The results of the experimental and analytical
  research projects have been reviewed by the Steel
  Joist Institutes Composite Joist Committee and
  the committee determined that it is possible to
  accurately predict the load-carrying capacities
  and deflection behavior of composite steel
  joists.

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Summary

• The Composite Joist Committee found that the
  ultimate strength models that were originally
  developed for composite wide flange beams are
  applicable to composite steel joists.
• Based on all the available information to date on
  the behavior of composite steel joists, the
  committee was able to develop the new Standard
  Specifications for Composite Steel Joists,
  CJ-Series

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Any Questions?
SJI Website http//www.steeljoist.org/composite