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Re: Knee Brace Literature

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Dear Stan Scholl,

For comparison of deflection, four simple structures consisting single
bay ( Plane Frame) are modeled (in STAAD). All four structures are
modeled with moment resisting frames and thereafter with knee bracing.
Sizes of members are identical in all the cases. Lateral load was
applied and deflection was checked at the top story for both the
cases. Following shows the brief details of STAAD model and comparison
of the results.

Brief Details of STAAD models

1)	Model 1 :   3m x 3m height
2)	Model 2 :   3m x 6m height
3)	Model 3 :   3m x 9m height
4)	Model 4 :   3m x 12m height

 Supports are hinged at the foundation level. Knee bracings are
provided below the beams only. In case of knee braced structure,
moment at the beam-column junctions are released.

Comparison of the results

       % Increase in deflection at top story in case of Moment
resisting frame & Knee braced Structure :

1)	Model 1 :  - 9.6 %
2)	Model 2 :  - 2.6 %
3)	Model 3 :   +12 %
4)	Model 4 :   +15 %

Above values shows that in case of structures having more than two
story, lateral deflection at top story may increase for knee braced
structure as compared to Moment resisting frames. ( Please note that
these values are derived for the specific structures only and may vary
significantly for complex structures. )

Kindly share your experience regarding similar comparison of the
results for more complex structures.


Bhavin Shah

On 2/2/06, sscholl2(--nospam--at) <sscholl2(--nospam--at)> wrote:
> my experience (45 yrs.) is that knee braces always reduce deflection
> significantly.
> all knee braces I have used are under beams only.
> Stan Scholl, P.E.
> Laguna Beach, CA

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