Types of eccentric braced frames

Types of eccentric braced frames


However, they are of questionable value in seismic regions because of their poor inelastic behavior. Although moment-resistant frames exhibit considerable energy dissipation characteristics, they are relatively flexible when sized from strength considerations alone.
Eccentric bracing is a unique structural system that attempts to combine the strength and stiffness of a braced frame with the inelastic energy dissipation characteristics of a moment frame. The system is called eccentric because deliberate eccentricities are designed within the system, typically within the beam segment. 

The eccentric beam element designed as a fuse limits large forces from entering the braces. The eccentric segment of the beam, called the link, undergoes flexural or shear yielding prior to buckling of compression members. Thus, the system maintains stability even under large inelastic deformations. 

The required stiffness during wind storms or minor earthquakes is maintained because no plastic hinges are formed under these loads and all behavior is elastic. Although the deformation is larger than in a concentrically braced frame because of bending deformation of the “fuse,” its contribution to deflection is not significant because of the relatively small length of the fuse. 

Thus, the elastic stiffness of an eccentrically braced frame can be considered the same as the concentrically braced frame for all practical purposes.click here to continue read

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