Shear design, 4" wall - Serviceability limit state

[killi]

- 4 storey building in Norway. Floor slabs of precast hollowcore floor slabs spanning 14m (46') fram outer wall to outer wall

- Precast concrete sandwich wall elements: 7,5m (23') wide, 3m (10') tall.

- Two large windows in each element separated by a 500mm (20") column. 300mm (12") columns each side. Distance top windows to bottom floor slab: 1m (3')
_____________
_____________ 3" outer layer, aprox

insulation
_____________
_____________ 4" inner layer, aprox

The inner layer will be heavily loaded (85kN/m ultimate limit state) by the next deck up above the windows, so the norm here in Norway is to increase the thickness of the inner layer and do a beam calculation.

Instead I did a shear wall analysis for the inner layer, and found that a 100mm (4") wall thickness is acceptable for ultimate limit state.

I do however, not have the knowhow or software to check for serviceability limit state: Cracking, deflection etc.

There will be about a hundred of these wall sections, and I have cold feet, and will probably end up specifying a beam construction.

Any good methods online? Anyone design a lot of these wall sections? Common practice where you live?

Thanks

 

[oldrunner]

In the 1950's a number of tilt-up buildings that were constructed similarly to your description. They can be described as sandwich panels. You didn't describe the reinforcing, both in plane and perpindicular.

Similar methods exist today in products such as Insteel and Impact panels. These consist of a welded wire mesh double space grid with diagonal rigid wires connecting the two grids separated by some distance. Between the two faces of the mesh grids, foam is placed. The completed panels are 4 feet by 8 feet and are shipped to the job site. At the job site, they are placed on their supports, setting up like playing cards. At each joint, there are splicing wire mesh attached on each face to provide steel continuity.

After all of the pieces are connected and the doors, windows , electrical and plumbing, then the concrete is applied, either by shot-creting or by pumping and hand finishing.

Your system probably cast them on the ground or at a factory and were hauled to the site.

We prepared a design manual in the 1970's for one of the original systems called W-Panels.

There is also a semi-text book published by a San Francisco bay area engineer that was very very good, but it is my office and I'll try to access it in the next few days.

Now matter where your investigation takes you, make sure that there is a continuous load path through out the structure, which would include looking at how the panels are connected to the structure.