Shear vs. Moment for wind resistance

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    Michael Ermann

    Ha! I just re-read my first comment. Foiled by autocorrect. It should have read. . . 

    Better to resist lateral forces of wind or SEISMIC:
    Moment-connected frames
    Or cross bracing
    Or shear walls
    And generally, ductility (steel) outperforms brittle (masonry)

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    Rebekka O'Melia

    For starters, a 'shear wall' isn't going to be a structural steel wall with a lot of connections.

    A shear wall is going to be a solid masonry (concrete) wall.  Think monolithic.  

    A structural steel wall can be a braced frame or moment frame.  A moment frame has 2-way rigid connections, web & flange.  

    All the above can resist lateral forces.  Shear walls can resist the most, then braced frames, and moment connections resist the least.

    Hope this helps!

    Rebekka O'Melia, Registered Architect, NCARB, B. Arch, M. Ed, Step UP,  Step UP ARE 5.0 Courses

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    Michael Ermann

    Let's then answer your question with a question. . . 

    For seismic events, which strategy best protects buildings?

    Ductile structure

    Heavy structure

    Moment forces

    Shear connections

    . . . scroll down for the answer. .  . 

     

     

     

     

     

    A: Ductile structure

    Explanation


    And for seismic (but not necessarily wind) ductility (steel) outperforms brittle (unreinforced masonry). Click <<here>>

    Light wood stick construction, like steel, has a bend-but-don’t-break nature that makes it also perform well in an earthquake.

    Concrete, like masonry, is brittle and performs poorly in an earthquake (click <<here>>). . . unless there’s enough steel rebar in the concrete to make it relatively ductile (click <<here>>).

    Again, the names are, admittedly, confusing…..try not to relate “shear wall” or “moment connection” to shear force and moment force. (They do relate from a physics point of view but not intuitively for most of us)

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    Gang Chen

    A shear wall can be a reinforced masonry wall, a metal stud wall with plywood or OSB, a wood stud wall with plywood or OSB, a reinforced concrete wall, or walls made from many other materials…

    See the definition of a shear wall here:

    https://en.wikipedia.org/wiki/Shear_wall

    Gang Chen, Author, AIA, LEED AP BD+C (GreenExamEducation.com)

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    Michael Ermann

    Better to resist lateral forces of wind or seizure:
    Moment-connected frames
    Or cross bracing
    Or shear walls
    And generally, ductility (steel) outperforms brittle (masonry)

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    Michael Ermann

    The names are, admittedly, confusing…..try not to relate “shear wall” or “moment connection” to shear force and moment force. (They do relate from a physics point of view but not intuitively fir most of us)

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    Gang Chen

    Wind is one kind of lateral forces. For lateral forces like wind and earthquake, a rigid connection is typically better. 

    A hinged connection has little value in resisting lateral forces.

    Gang Chen, Author, AIA, LEED AP BD+C (GreenExamEducation.com)

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    Zachary Shedlock

    Thank you all.  This information is helpful in clarifying some key concepts.

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    Rebekka O'Melia (Edited )

    You're welcome Zachary!

    Rebekka O'Melia, Registered Architect, NCARB, B. Arch, M. Ed, Step UP,  Step UP ARE 5.0 Courses

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