Insulated Concrete Load Bearing Wall Penals

[Mian Muhammad Aslam]

 Wall panels are required to be designed which should be load bearing as well as insulated. A concept is developed to build such panels with total thickness of 8” (20 cm), having two layers of high-performance concrete sheets on the sides filled with the insulation, each of these two sheets to be of 3-4 cm thick reinforced concrete, using welded wire mesh as reinforcement, both sheets should be linked with vertical reinforced concrete ribs (columns) placed at short distance, in order to; (1) provide enough stiffness against axial load and buckling, (2) carrying the built-in beam to transfer the load of slab and (3) the entire panel will work as bracing for the frame structure to take the lateral loads in seismic zones. In addition to that the house construction with such panels is assumed to be more economical than the overall brick and concrete structure.

The question is that how can we perform the analysis and design calculation of such panels especially can we use ETABS to conduct such analysis and design calculations? If yes, please let me know how? As I have tried to find out in my ETABS 2016 but could not. There is a provision for core wall design but not the hollow insulated wall as mentioned above.

Thanks and best regards.

Aslam

[Simple Structures]

Here are a few observations - i am not a user of ETABS, so my comments are of a general nature.

1. Shear walls have large lateral (wind, earthquake) forces that are transferred from the floor diaphragms down to the foundations. The connections between precast wall panel and floors/columns should be able to transfer (shear) load; This often is not possible unless reinforcement crosses through the insulation and connects the wall to the floor/column element. You cannot rely on four connectors at corners or pure friction of concrete to concrete.

2. For a 200mm (8") panel, one would require minimum 50mm (2") insulation to achieve any meaningful thermal benefit. This leaves two concrete biscuits of 75mm each. I m assuming theses are connected around the perimeter only? Ii there any connection of reinforcement (truss-like) between the panels with panel area?

3. I think the system may be ok for say 2-storey low rise building.

4. For modelling i would take 200mm - 50mm = 150mm thick panel.

See what other learned colleagues say. 

[Ayesha]

This topic has been discussed in the forum in detail. Please check this topic.

 

Also, a good resource for masonry properties is  NCMA TEK 14-1A publication. You should be able to get it off google. I am attaching TEK 14-01B with this reply. It is a freely available resource. 

 

TEK 14-01B.pdf

[Mian Muhammad Aslam]

On 4/18/2020 at 6:24 PM, Simple Structures said:

Here are a few observations - i am not a user of ETABS, so my comments are of a general nature.

1. Shear walls have large lateral (wind, earthquake) forces that are transferred from the floor diaphragms down to the foundations. The connections between precast wall panel and floors/columns should be able to transfer (shear) load; This often is not possible unless reinforcement crosses through the insulation and connects the wall to the floor/column element. You cannot rely on four connectors at corners or pure friction of concrete to concrete.

2. For a 200mm (8") panel, one would require minimum 50mm (2") insulation to achieve any meaningful thermal benefit. This leaves two concrete biscuits of 75mm each. I m assuming theses are connected around the perimeter only? Ii there any connection of reinforcement (truss-like) between the panels with panel area?

3. I think the system may be ok for say 2-storey low rise building.

4. For modelling i would take 200mm - 50mm = 150mm thick panel.

See what other learned colleagues say. 

Thanks for your valid observations. Yes, there are a few elements which I supposed to mention which are follows:

1- The panels would not only be connected at four corners only to the plinth beam or foundation, if so, you are right; in such case we cannot transfer the sheer forces on the joints. Actually, both side layers of each panel have reinforced concrete connectivity at every 45-60 cm, which will increase the effective stiffness of overall panel to counter the buckling as well as to cary the load of beam and slab to the foundation. In addition to that these connectors will have the rebar dowels inserted coming out of the plinth beams or foundation. These inserted rebar dowels will be grouted with special grout having compressive strength of no less than 30-40N.  

2- Insulation is required to be of 100 cm think in order to increase the thermal insulation and to decrease the thickness of side layers concrete to 50 mm with concretors at 450-600 mm C/C. These elements of concrete (layers and connectors) will be made of high-performance concrete with increased ductility. Instead of considering 150mm thick simple sheer wall, we need to run it as a composite panel as mentioned, in order to acheive good ecconomy scale. This is the reason we need to run it in ETABS with different configration of this panwl to acheive the optimum thickness of the layers and connectors.   

3- Moreover, it is important to note that this concept will provide a highly effective bracing system, bracing all the beams and corner columns diagonally at both levels (top and bottom) which works well to counter high lateral loads.

Herewith attached is the section of panel for clearer picture.

Panel Design.pdf

[Mian Muhammad Aslam]

7 hours ago, Ayesha said:

This topic has been discussed in the forum in detail. Please check this topic.

 

Also, a good resource for masonry properties is  NCMA TEK 14-1A publication. You should be able to get it off google. I am attaching TEK 14-01B with this reply. It is a freely available resource. 

 

TEK 14-01B.pdf 261.57 kB · 1 download

Thanks for the document, it is useful to see the properties of blocks. We have been using such insulated blocks in UAE for long time. They provide good insulation and same time you can design load bearing walls too by some types of those blocks.