Tall buildings - using slab as a linking element
Tall buildings - using slab as a linking element
(OP)
Folks,
I am reviewing a tall building ETABS model.
The building has a central core and perimeter walls
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These perimeter walls are connected by extremely fine meshed slab elements to create what I assume is almost frame action on every floor.
I have never seen this done in the few buildings that I worked on. Is this common? Are you really gaining tremendous frame action from say an 8 or 10" slab spanning about 18 feet between the core wall and the perimeter wall?
Do you engineers use a rigid diaphragm constraint or model shell elements explicity to engage perimeters walls or columns?
Any input is appreciated.
Thanks
I am reviewing a tall building ETABS model.
The building has a central core and perimeter walls
---------------------
| | | | |
--------------
| |
| |
--------------
| | | | |
---------------------
These perimeter walls are connected by extremely fine meshed slab elements to create what I assume is almost frame action on every floor.
I have never seen this done in the few buildings that I worked on. Is this common? Are you really gaining tremendous frame action from say an 8 or 10" slab spanning about 18 feet between the core wall and the perimeter wall?
Do you engineers use a rigid diaphragm constraint or model shell elements explicity to engage perimeters walls or columns?
Any input is appreciated.
Thanks






RE: Tall buildings - using slab as a linking element
RE: Tall buildings - using slab as a linking element
I am looking for information regarding what other engineering firms do in these situations when are trying to engage frame action to squeeze every bit out of the system.
RE: Tall buildings - using slab as a linking element
As for modeling it, the slab is useful for transferring any lateral loads from the outside wall to the inner core and vice versa.
RE: Tall buildings - using slab as a linking element
I understand the concept, however, my questions are more pertaining to structural modeling.
Examples of such questions are:
1. Do you use shell or plate elements for your slab modeling?
2. How fine is the meshing for the same?
3. Do you use a rigid diaphragm constraint and not model the slab?
4. Do you use equivalent beams (effective slab width) for modeling?
5. What is the correlation between simple frame models and full 3D models?
I am sure the answers to these questions are going to be very varied, but I would appreciate all input nonetheless.
RE: Tall buildings - using slab as a linking element
2. Start with course meshing. After analysis look at the mesh. If the contours jump from one mesh to the next, refine that area (I beleive for ETABS you have to turn off an automatic meshing refinement procedure)
3. For a tall building, I would be tempted to model the actual slab. I might start with a rigid link to get an idea first but then continue to an actual flexible slab model.
4. I would consider the design of the building separate from the design of the floor slab. When modeling the whole building, the floor slab is used in diaphragm action. After getting the results for the lateral system, I would come back and model a typical floor (or just do the floor design calculations by hand)
5. Not sure. Isn't simple frame a 2D model?
Been out of the ETABs - SAP world for some time so some of my responses might not be entirely pertinent.
RE: Tall buildings - using slab as a linking element