C243 probable maximum moment at plastic hinge the

This preview shows page 61 - 62 out of 90 pages.

C2.4.3 Probable Maximum Moment at Plastic Hinge The probable plastic moment at the plastic hinge is intended to be a conservative estimate of the maximum moment likely to be developed by the connection under cyclic inelastic response. It includes consideration of likely material overstrength and strain hardening. C2.4.4 Beam Flange Continuity Plates Beam flange continuity plates serve several purposes in moment connections. They help to distribute beam flange forces to the column web, they stiffen the col- umn web to prevent local crippling under the concentrated beam-flange forces and they minimize stress concentrations that can occur in the joint between beam flange and column due to non-uniform stiffness of the attached elements. When the beam flange connects to the flange of a wide-flange, built-up I-shape or cruciform W -shaped column in which the column extends above and below the beam and the column flange thickness satisfies Equations 2.4.4-1 and 2.4.4-2, con- tinuity plates are not required as beam-flange forces can be adequately trans- ferred to the column webs without the stiffening effects and secondary load paths provided by these plates. However, these equations have been developed based on consideration of the behavior of columns in lower stories of buildings, where the column extends a considerable distance above the top flange of the connected beam. Equations 2.4.4-1 and 2.4.4-2 do not apply in the top story of a building, where the column terminates at approximately the level of the top flange of the beam. In such cases beam-flange continuity plates or column cap plates, having a thickness not less than that of the connected beam flange, should be provided. Figure C–2.2 presents a detail for such a connection, where the beam flange is welded directly to the cap plate and the cap plate is welded to the column so as to deliver the beam-flange forces to the column web. Alternatively, if the column projects sufficiently above the beam top flange, Equations 2.4.4-1 and 2.4.4.-2 can be considered valid. Although comprehen- sive research to establish the necessary distance the column must extend above the beam for this purpose has not been performed, it may be sufficient if the col- umn is extended a distance not less than d c /2 or b f /2, whichever is less, above the top beam flange. For boxed wide-flange section columns in which the beams are connected to the flange of the I-shaped section, Equations 2.4.4-3 and 2.4.4-4 have been developed to provide a similar stiffness of column flange as that provided by Equations 2.4.4-1 and 2.4.4-2 for unboxed sections. As with Equations 2.4.4-1 and 2.4.4-2, Equations 2.4.4-3 and 2.4.4-4 are not strictly valid for the case of a moment
Image of page 61

Subscribe to view the full document.

6.2 –54 COMMENTARY Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications A MERICAN I NSTITUTE OF S TEEL C ONSTRUCTION , I NC .
Image of page 62
You've reached the end of this preview.
  • Winter '14
  • Tensile strength, Steel Moment Frames, American Institute of Steel, Intermediate Steel Moment

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern