Some of your structures that u added are unstable. Check also when the analysis is running the mode shapes to see if there is anything suspicious and if etabs is indicating some unstable structure.
If.not chexk that u have enough space on your disk. It may be as easy as this.
check the area spring of your raft in which direction you made it. U should have springs or restraints in the 3 directions in order for your building to be stable.
Check the unsupported length considered by the program. If the program is not considering the beams which will brace your column, then overwrite it. Otherwise, if the height is correct, then you have a big axial force which is exceeding the Euler force. Don't forget that the ultimate axial force...
the non iterative consider ur dead loads as ur vertical loads only. That's why u have smaller second order moments
generally, it is used as a preliminary design since it is faster. I never use it
Hi.
1- u can assign moment releases for all the columns or assign a stiffness modifiers to their bending moment in the 2 axes of the column equal to 0.01.
2- after defining the wind load cases, u should assign ur diaphragms and then u are ready to run the calculations.
M11, M22 are the moments in the 2 directions of the deck and M12 is the twisting moment.
If you want to know which one corresponds to which direction, display ur local axis and M11 is the moment along axis 1 as well for M22.
You can also check the magnitude of moment and deduce which one is your...
To each segment of the spandrel u should assign a spandrel label. Otherwise it wont work.
For example, if ur beam is divided into 10 parts, eaxh part should be assigned a spandrel name.
Sorry for the late message. Attached a screenshot of the auto labeling of the spandrel. http://files.engineering.com/getfile.aspx?folder=b793be7e-5c81-40f7-a9fc-72d62f652930&file=spandrel.jpg
4d modeler,
u can find the autolabeling thing when u pick the spandrel option and begin to draw.
i dont etabs on the computer i am using. once i am home i will screenshot it for u.
regarding the slab mold and since u will design it as s slab, use the forces in the spandrel m11 m22 m12 and the...
The autolabeling figures when u select the wall definituon and wants to draw it. Have a look there. U will find it.
As.for the slab mold, display the forces on your spandrel (f11 f22 f12 m11 m22 and m12) and design ur drop accordingly.
As i told u personally i prefer to analyse a drop of 1 m as...
Right. Chexk the autolabeling of spandrel it will economise a lot of time.
Personally i model the slab folds as beam spanning between support since there will be no continuuty between the 2 levels except by this member.
Can u tell me how are u planning to design it as a slab fold ? U can also...
U can check in the participation mass the percentage of mass that has been captured in the x, y and rotations rz components.
Based on the participation mass, u can easily deduct if your first modes are translational or rotational.
Your model should include all the elements of the substructure as well as the superstructurr.
Morover, u have to consider the backstay effect in the podiums since there will a sudden change in stiffness between the basement level and the first floor of your tower.
Hi,
U are right. he doesn't include the snow in the load combinations. u can create the default load combinations and then modify it to include the snow load case.
ACI includes in the load combinations the snow but Etabs doesn't recognize it.
