Joist fundamental frequency

Krzyszek-Young Man,

Nobody is likely to be of help. f=1.57√(386EI/WL³).

Please go back to the article--he would have defined every term .

And he would have defined the frequency of natural vibration OF BEAM* -had it been loaded at midspan* with load W*LBS*

* -all I am guessing.

Let say, w=uniform dead load (weight of floor) supported by the joist in psf.

s=spacing of joists in ft.

j= wt. of joist, in pounds per foot

then, total dead load supported W= w*s + j (in pounds per foot uniformly distributed for the joist span L)

Hope this helps.

Thanks, That is exActly what I was looking for.

Not sure understand the question... but, dead load (if that's what you're asking) usually refers to the weight of the structure itself (along with any permanent fixtures thereto). Live load would be anything supported by the structure...such as persons walking atop whatever was supported by the joists. It could also include loading caused by natural phemomenon...such as weather effects: wind, water, snow....

Unlike live loads, deadloading is almost invariably in down direction. Dead load does not move or shift...hence, "dead" load. Total load (rating) is dead plus live. Hoping your question was this simple. Sorry if not.

Assuming that damping is not involved, the formula that you mentioned is of the form omega = sqrt(k/m). Where, k, is the stiffness of the structure. Which usually is of the form, EI over L cubed. The W in your formula is a uniform load. You can find a full explanation in "Dynamics of Structures" by Chopra in your college library.