Page 69 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

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Source: STRUCTURAL STEEL DESIGNER'S HANDBOOK

CHAPTER 3

CONNECTIONS

Larry S. Muir, P.E.
Chief Engineer, Cives Steel Company
President, Cives Engineering Corporation
Roswell, Georgia
William A.Thornton, Ph.D., P.E.
Corporate Consultant, Cives Corporation
Roswell, Georgia

In this chapter, the term connection is used in a general sense to include all types of joints in struc-
tural steel made with fasteners or welds. Emphasis is placed on the more commonly used connec-
tions, such as shear connections, beam-to-column moment connections, and axial force connections
including main-member splices, bracing connections, and truss connections.
Recommendations apply to buildings that are not subject to special detailing requirements due to
seismic loading. This material is generally based on the American Institute of Steel Construction
(AISC), “Specification for Structural Steel Buildings,” 2005, referred to herein as the AISC
Specification. This new unified specification includes both load and resistance factor design (LRFD)
and allowable strength design (ASD), with common expressions for nominal strength. All examples in
this chapter are given in LRFD format, but most of the procedures are readily adaptable to ASD. See
Chap. 5 for further discussion of design methods and terminology. For additional considerations in
seismic applications, see AISC, “Seismic Provisions for Structural Steel Buildings,” 2005, and Chap. 8.

3.1 GENERAL CONSIDERATIONS FOR CONNECTION DESIGN

3.1.1 To Connect, to Join, to Make Whole—the Job of the Connection
Design Engineer
To connect or to join is to bring together so as to make continuous or form a unit. In steel structures,
this bringing together is usually accomplished through the use of fasteners (primarily bolts) and
welds, along with secondary plates, angles, or other steel pieces. When designing structural steel
connections, the goal is to unite the parts in such a way that the basic assumptions made during the
analysis are supported by the as-built conditions. Of course, the assumptions made during analysis
can rarely be precisely replicated. Pinned supports are almost never truly pinned, and fixed supports
are almost never truly fixed; but by diligently sizing connection elements to accommodate these
differences, the connection design engineer can design connections that will closely approximate the
assumed behavior, or at least accommodate the differences that inevitably exist.

3.1
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