TWO WAY SLAB WITH BEAMS

[fratrowie]

hello pals,

im designing a two way slab with beams which is cannot be done by direct design method but the problem is i dont know to how to used equivalent frame method, i believe that it needs a table brows for nonprismatic and the like to get the work done, dont have much researched sources in our locality but i try to solve it any way, first i compare it to direct design method for it say's that the result of two method are closed if the frame in question is workable with direct design method, meet ACI requirements to wit; span ratio, load ratio and 10% least column offset. the result indeed in the end span, the exterior negative moment is closed result but the interior negative moment is way down by 10%, the distribution factor is correct, fixed end moment used WL²/12, moment carry over 0.50.
Moment carry over factor and fixed end moment used are correct?

your reply is much appreciated;
fratrowie

 

[socks15]

Well it's been a about 5 years since I even considered a two way slab. I'm more of a steel guy anyways.

I'm not too clear on your situation and some of the criteria. Can you not use the direct method because you have less than two spans (13.6.1.1)? If this is a small area I think I'd just use wl^2/8 top and bottom to be conservative and be done with it.

That's just my two cents worth.

 

[socks15]

Whoops! Meant 3 spans!

 

[fratrowie]

socks15,

i used an identical frame with three spans in this comparison of the two methods, direct design method as appoximation to check the results, hoping that i can sort out the nonprismatic equivalent frame method.

thanks for your reply, merry chrismas.

fratrowie