Frameworks for Lateral Loads
    Lecture 2
    Arch 721, Structural Design for Dynamic Loads, University of Virginia
     Copyright © 1996-2006 Kirk Martini. 29-Aug-2007 8:39     		Table of
    Contents

    Today's Topics

    • Lab Discussion
    • Review of Behavior Concepts (Arch 324, Lecture 8)
      • Strength, Stiffness, Stability, Ductility

    • Overall behavior of lateral force resisting systems.
    • Frameworks
      • Braced frames, Moment-resisting frames, eccentric-braced frames
    • Upcoming lab exercise.

    Overall System Behavior

    What happens when you push a building?

    Concepts and Terminology

    Horizontal and Vertical Systems
         The lateral-load resisting system of a building can be subdivided into horizontal and vertical subsystems.
    Horizontal Systems = "Diaphragms"
    The horizontal systems (typically called diaphragms) resist horizontal forces induced by wind or earthquake and transfer these forces to the vertical systems, which then take the forces to the ground.
    Diaphragms are like large beams
    Diaphragms tyically act like large simply supported beams spanning between vertical systems.
    Vertical systems are large cantilevers
    Vertical systems typically act like large cantilevers spanning vertically out of the ground.
    Today: Vertical systems that are frameworks
    Vertical systems constructed as frameworks include moment resisting frames, braced frames, and eccentric-braced frames.

    Moment-resisting frames (aka "moment frames", "rigid frames")

    Braced frames

    Comparing braced and moment frames

    Viewing frames as cantilevers

    [demo]

    Examples

    Arch 721, Structural Design for Dynamic Loads, University of Virginia
     Copyright © 1996-2006 Kirk Martini. 29-Aug-2007 8:39    		 Table of
    Contents