Frame Element with Shell element 1

[IYIeI2cY]

hi there, i have a question ,

Can i solve a problem using shell elements and frame elemnts together?? coz when i tried to do so, i noticed that the results in the frame elemnt is strange, it looks like the shell carries the frame elemnts (beams).

that made me solve the floor twice, one time to get the streeses in the shells and the other to get the reactions.

any other way around !!


Pea$e

 

not sure the exact nature of your problem since you typically connect shells and beam elements at shared joints. There is no reason why the shell would carry the frame unless you modeled it that way. Y always get shell output for stresses and joint reactions in the same run

Another way to connect beam joint with shell joint(s) is using Assign menu>Joint>constraint, Add body type. This enables you to rigidly link joints which are offset from one another. If you have a 4 foot thick shell, for example, and want to connect beam to outer face 2 feet away, you can select joints and Assign a constraint.

 

[IYIeI2cY]

i think i didnt make it clear !!

for example, when i put an extreroir beam shared the same joints with the shells, we should expect negative moments in the shells , that dosnet happen, it only decrease the postitive moment but dont give -Ve moment !!

it solve it as panelled beams ,not rigid beams, the rigidity as not we assume in manual solve.

thats what i meant, i hope u got an answer for that,

thx in advance

Pea$e

 

Pease, not enough info to offer any help. What are your boundary conditions? More info needed on geometry and loading.

 

[IYIeI2cY]

im just saying that when u solve a plan (beams and slabs), we should expect -ve moments in the slabs over the interior beams as there is Continuty in slabs, but when we solve frame elements and shell elements we found that the slab over the interior beams got +ve moment not -ve, it looks like it assume it is not full rigid,

is there any way to make the sap2000, assume that the beams is full rigid so it get -ve moments in the slab sections above the beams !!!

thx for concern

hmmmmmmm, Pea$E

 

In order to define a rigid beam/frame, you will have to first define a new material and give it a very large modulus of elasticity. Then define a new frame section, add a large rectangle for example, and use the newly defined rigid material for this section

 

[IYIeI2cY]

thx for help, but hmmm, in this case, what will affect the frame elements !! the results for the beams will be true or not ?? will the moments and deflection be right ??



any way thx for your Conceren, thats appreciated


Pea$e

 

[zliazmei]

When you are modeling floors wit frame and shell ellements it is not allays shure that you will have -Moments over interior beams. Sometimes the stiffness of beams is not so big so when they deformed dounwards the negative moment may not occure. (As SAP is using deformation methods when calculating stressess and forces). So you will find corect result modeling floor this way.
But in most cases we assume that beam are fully rigid and we are using bi calculation method you describe above. if you can try CSI "SAFE" it is specialy made for plates.

Hope this helps