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[kapildingare]

Resp Sefians,
                                     What wouldbe the difference in load sharing in two cases,
<if>1)     <endif>Tall R.C.C. building with all walls (internal aswell as external) as R.C.C. structural walls,in which type all walls columns,beams are casted together(like in aluminum formwork like in Mihan or similar)
<if>2)     <endif>Tall R.C.C. framed buildings with walls as partitionwalls and non structural members in which frames are made first and  non structural partitions later.

<o> </o>
With respect to following points
1) What type of loads R.C.C. walls wouldcarry?
2) Would bending in beams in both the casessame or different ?
3) Would columns carry same axial force andmoments in both the cases?
4) Would these walls act as shear walls?What would be their role with respect to lateral loads?
5) If these walls are discontinued at stiltfloor what precautions are taken to offset such high stiffness discontinuity?
6) In analyzing such frames with structuralwalls how these walls are modeled?
<o> </o>
                                  Thank you ,verymuch.
<o> </o>
<o> </o>
                                                                                                         KapilDingare

[suraj]

RCC Walls On All Stories<xml><o></o>
1       On tall buildings, higher levels tend to sway more than lower levels<o></o>
2       When all floors are designed column less RCC walls at all locations including external shear walls, structure shall become rigid in approach & its conduct<o></o>
3       Though all internal walls can be considered as structural RCC walls without including as columns, which conduct shall certainly reduce horizontal deflection<o></o>
4       But, rigidity increase would render structure less resistant to seismic forces<o></o>
5       In case of all walls as RCC, no beams may be required at slab level, yet should be so considered, beams should preferably be poured with slabs for monolithic action for diaphragm <o></o>
6       Even part of walls can be considered to act with columns for loads sharing, but not whole length<o></o>
7       RCC walls should be used for lateral loads sharing & resisting other loads<o></o>
8       Option for RCC framing in combination with non load bearing internal walling & external shear wall, constitute a better arrangement from structural view point, allowing structural to considerable extent remain flexible<o></o>
9       Walls if so provided makes core part stronger & more rigid<o></o>
10  But, services provisions spaces cannot be ignored, which causes issues for implementation in case of all RCC walls<o></o>
<o> </o>
<o> </o>
<o> </o>

[bijay sarkar]

Dear Sir,

Economics does not permit for all rcc wall building.


with regards,

bijay sarkar

[suraj]

Dear Eng
Bijay Sarkar
RCC Walls

1. Absolutely agree with your contention pertinent economical factor involved, when including all RCC walls, which is also, commonly understood by every person
   
2. We know that no such building involves inclusion of all RCC walls except with shear & external walls for certain requirement specifically, where blast resilience or resistance is required/demanded
   
3. But discussion regarding comparison is to be made, when query raised

[Dr. N. Subramanian]

Dear  Er Kapil Dingare

Yes. I agree with the views of Er Bijay.
Why do you want to have all RCC wall buildings?

Best wishes,
NS

[biju]

Dear Mr. KapilDingare,

There are many tall buildings coming up with this framing system ( All walls in RCC )now a days. The advantage is that there will not be any projections inside the rooms, Architect/end users are happy.
Speed  of construction increases rapidly, will have better finishes, better member joints, increase in the usable carpet area, much stiffer structure to resist wind effects, and abundance of shear walls in both directions to resist seismic forces etc...

The disadvantage is that no future modifications or breaking of walls, partly or fully is possible.  Also need of skilled labors, good quality control,proper design and detailing, and no more changes once the construction has started.

The cost of construction does not increase much, and found that in some cases, there is actually a reduction in the overall cost.

regards,

Biju.




<if>1)     <endif>Tall R.C.C. building with all walls (internal aswell as external) as R.C.C. structural walls,in which type all walls columns,beams are casted together(like in aluminum formwork like in Mihan or similar)
<if>2)     <endif>Tall R.C.C. framed buildings with walls as partitionwalls and non structural members in which frames are made first and  non structural partitions later.

<o> </o>
With respect to following points
1) What type of loads R.C.C. walls wouldcarry?
2) Would bending in beams in both the casessame or different ?
3) Would columns carry same axial force andmoments in both the cases?
4) Would these walls act as shear walls?What would be their role with respect to lateral loads?
5) If these walls are discontinued at stiltfloor what precautions are taken to offset such high stiffness discontinuity?
6) In analyzing such frames with structuralwalls how these walls are modeled?
<o> </o>
                                  Thank you ,verymuch.
<o> </o>
<o> </o>
                                                                                                         KapilDingare[/quote]

[suraj]

Tall Buildings With RCC Walls
Dear Eng Biju

1. Inclusion of all RCC walls is not bad an idea to an extent cost is confined within equivalence to other systems
   
2. Shall you clarify about internal walls whether or not, 150 mm thick since, higher thickness would add to load & cost?
   
3. I presume that you have compared cost factors on both system rigid & flexible
   
4. It is an acceptable fact if economy permits, RCC walls could be an alternative option, provided structural adequacy/sustainability permit/s for both seismic as well as, wind forces considerations
   
5. In such case, even precast slab panels can be included efficiently avoiding waiting period for slab striking time
   
6. Otherwise, beams may not at all be required at slab level as wall tops/turrets could be converted to beams
   
7. But, heavy walls would add to cost & load of structure, leading to uneconomical designs
   
8. Accurate shop drawings are required in such cases for all services due to fact that block outs cannot be relocated generally, while dismantling & rework shall pose headaches for designer & site manager
   
9. Shall some data be posted in case it is available?

[kapildingare]

Resp Dr Subramanian and Er Suraj Singh,

Views by Er.Biju
Speed  of construction increases rapidly, will have better finishes, better member joints, increase in the usable carpet area, much stiffer structure to resist wind effects, and abundance of shear walls in both directions to resist seismic forces etc...

The disadvantage is that no future modifications or breaking of walls, partly or fully is possible.  Also need of skilled labors, good quality control,proper design and detailing, and no more changes once the construction has started.

The cost of construction does not increase much, and found that in some cases, there is actually a reduction in the overall cost


I fully agree with this but would like Dr’s opinion (also Jameschan please) about other points such as,
1)     What type of loads R.C.C. walls would carry?
2) Would bending in beams in both the cases same or different ?
3) Would columns carry same axial force and moments in both the cases?
4) Would these walls act as shear walls? What would be their role with respect to lateral loads?
5) If these walls are discontinued at stilt floor what precautions are taken to offset such high stiffness discontinuity?
6) In analyzing such frames with structural walls how these walls are modeled?


Thank you.

                                                                        Kapil Dingare

[biju]

Resp Er Suraj Singh,

Pls. scroll down for my inputs,

1. I agree

2. Walls up to 175 mm and beyond are not advisable in the cost front and they will turn out to increase the RCC volume heavily.

3. Yes, generally speaking these systems are not economical. But as you know, there are many parameters which can affect cost, depending upon the project nature, location, geometry, construction time etc.

4. I agree. Infact these systems, if we get symmetry of walls in both direction and as per the requirement, are better to resist lateral loads.

5. 8 days cycle can be achieved even with this scheme.  As we go for pre-cast panel, then the advantage of the slab stiffness in the analysis may miss out.

6. Beams are there only for the openings.

7. Pls. see my point no.2

8. Service ducts can be managed later on also, as the cut out size will not pose much issue structurally. But no Arch. changes are possible.

9. Will try to dig up some numbers from the past and post later.

regards,

Biju.

[suraj]

Dear Eng Biju & Eng
Kapil Dingare
RCC Internal Walls on buildings

1. 
   Generally, hollow concrete blocks are included for all types of filling in non structural walls on building, while in ours, bricks are provided in
   
2. 
   HCB are manufacturer 7/9/12 N strength
   
3. 
   These walls are connected to structural framing columns by wall ties using shot firing bullets, so that block walls remain intact with columns on non rigidity basis
   
4. 
   Nominal reinforcing bars are included to maintain stability of walling
   
5. 
   In ours, such arrangements are not made & only in general, bricks are included for construction of nominal walls, without any specific stability connections
   
6. 
   Your proposition is for replacing such block or brick walls within structural framing, which method to considerable extent can be engineering wise accepted
   
7. 
   It is also, accepted that production/delivery shall be clean & quality base provided, expertise is available on line management
   
8. 
   Since, 150/175 mm walling is considered for such non structural members, no double reinforcing mesh arrangement shall be virtually feasible keeping provision pertinent concrete spacers on both sides, which should be at least 40/50 mm each side depending on climatic conditions to which concrete is exposed
   
9. 
   Suggestion that services inserts shall be added later or no block outs should be provided is not supported on important works
   
10. 
    I have experienced lot of clashes on interface coordination & many alterations are made & recorded for future reference
    
11. 
    Tall buildings shall be voluminous coordination works to an extent allied services are concerned
    
12. 
    We should understand that services successful performance is also, equivalent to structural performance & not founded on lower profiles
    
13. 
    Of course, internal RCC walls shall support fire resistance of localised areas & prevent spread of fire or reduce plastic stage reaching time
    
14. 
    Even in place of 2 hours fire resistance, one hour may be augmented depending on situation.
    
15. 
    I have just stated based on assumption without any engineering reference
    
16. 
    Another issue to be cordially, included with provision of RCC walls is about application of finishes
    
17. 
    In case, plastering or rendering require to be applied on surfaces of concrete walls, it shall pose scabbling application immediately, after forms are struck
    
18. 
    In case, no such provision is required in specifications, paint may debond/peel after few years, whereon not even bonding agent is successful
    
19. 
    If not scabbling, grit blasting may be required to roughen surfaces prior to painting to achieve define SA 2/2.5
    
20. 
    When plastering or rendering may not be required, but wall lining including cement & gypsum board be required to cover walls, it shall not be economical, since backing frame for such boards are expensive
    
    
21. 
    To an extent, case of precast hollow panels is concerned, what I had stated that diaphragm action is achieved successfully for whole system by adding thin RCC slab on precast panels, enabling system to act on similar pattern as monolithic slab & beams casting behaves
    
22. 
    Lateral loading should not be mixed with gravity loading
    
23. 
    Thickness 150 mm cannot be considered for transferring loads from wind or from seismic action
    
24. 
    Such walls can be considered for added stability only
    
25. 
    Of course, these walls shall assist structure being additionally rigid, but their use as shear walls may not be allowed in general
    
26. 
    Energy dissipation by structure shall decrease during impact, which consequence does not support thick walls as well
    
27. 
    Nominal replacement just for architectural & decoration may be fine
    
28. 
    I shall also suggest that column sizes should not be reduced, but columns rigidity would certainly increase due to internal walls, provided no door opening or other major opening is located in wall, while walls through which openings do exist, may not extend additional rigidity