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[B.V.Harsoda]

The 14th World Conference on Earthquake Engineering

October 12-17, 2008, Beijing, China
Study of Structural RC Shear Wall System in a 56-Story RC Tall Building

ABSTRACT:
In recent decades, shear walls and tube structures are the most appropriate structural forms, which have caused the height of concrete buildings to be soared. So, recent RC tall buildings would have more complicated structural behavior than before. Therefore, studying the structural systems and associated behavior of these
types of structures would be very interesting. Here in this paper; we will study the structural aspects of one of the tallest RC buildings, located in the high seismic zone, with 56 stories. In this Tower, shear wall system with irregular openings are utilized under both lateral and gravity loads, and may result some especial issues in the
behavior of structural elements such as shear walls, coupling beams and etc. To have a seismic evaluation of the Tower, a lot of non-linear analyses were performed to verify its behavior with the most prevalent retrofitting guidelines like FEMA 356. In this paper; some especial aspects of the tower and the assessment of its seismic
load bearing system with considering some important factors will be discussed. Finally after a general study of ductility levels in shear walls; we will conclude the optimality and conceptuality of the tower design. Finally, having some technical information about the structural behavior of the case would be very fascinating and useful for designers.

Source Link:-
http://www.iitk.ac.in/nicee/wcee/article/14_05-03-0155.pdf


Regards,

B.V.Harsoda

[B.V.Harsoda]

The 14th World Conference on Earthquake Engineering


October 12�17, 2008, Beijing, China
AMBIENT VIBRATION MEASUREMENT AND EARTHQUAKE RESISTANT BEHAVIOR ANALYSIS ON A TWO�TOWER TALL BUILDING WITH ENLARGED BASE

ABSTRACT :
The two�tower building with enlarged base is a high�rise building form favored by the architect. In this paper the ambient vibration measurement was conducted on a 86�meters�high frame�wall tall building. This building consists of two towers connected by air corridors and an enlarged base. Translational and torsional modes are measured. SATWE module in PKPM software is used to model the 1structure and the analytical modes are calculated. It is found that due to the eccentricity of the air corridors, each mode shape in the structure has component of torsional vibration, and the higher modes are all torsional modes. In comparison with the
experiential formulas used in calculating fundamental period of tall building in different country, it is found that the measured fundamental period of the structure is higher than the results by calculation. It shows that the measured stiffness of the structure is higher than that of the analytical model. At last the designed ground motions are used in the elastic dynamic time history analysis by using Newmark�b method, and the results show that the response forces concentrate on the transfer story and the highest air corridor on the top of the tower, and the shear forces have greatly changed. Due to the connection of the air corridor, the bending moments and lateral displacements are approximately equal to each other in X and Y direction.

Source Link:-
http://www.iitk.ac.in/nicee/wcee/article/14_12-01-0075.PDF

Regards,
B. V. Harsoda

[suraj]

Observation pertinent article 2.1

1. Quantities regarding concrete is 1 cum per sqm
   
2. Reinforcing bar 26000 T for 125000 cum concrete
   
   
3. These are too high coefficients
   
4. Tall building is not convinced by such high volumes

http://www.iitk.ac.in/nicee/wcee/article/14_05-03-0155.pdf

2.1

Structural system

Main walls are RC shear walls with regular staggered openings. Sidewalls are also RC shear walls, connected to

the main walls with coupling beams. Some of sidewalls contain continuous column of openings and the rest are

solid.

Figure 1 The view and structural system of the tower

Table 1.1 Summary of the tower properties

No. Elevations 56

Height 173 m

Typical floor area 3000 m 2

Effective residential area 126000 m2

Structural system Coupled shear wall

Volume of concrete 125�000 m3

Weight of reinforcement 26�000 ton.

Steel weight per area 200 kg/m2

Number of Individuals 571

Foundation Mat

[bijay sarkar]

Dear Sir,

I agree with the views of Suraj Sir that if RCC quantity is 1,25,000 Cum, reinforcement quantity of 26,000 Ton is too much high. It should be in the range of 15,000 MT considering it as wind affected building.


with regards,

bijay sarkar

[thirumalaichettiar]

Dear Er.Bijay sarkar,

On what basis you are quoting "It should be in the range of 15,000 MT considering it as wind affected building"?

Can you post some reference or literature to support your statement?

T.RangaRajan.

[suraj]

Observation pertinent article 2.1

1. Just repeat my comments duly amended as follows
   
2. Quantities reported on study appears to be incorrect to my presumptive assessment
   
3. RCC 126000 cum for 125000 sqm is based on typical floor 3000 sqm
   
4. Provision 1cum (including all elements)/sqm slab is an excessive load in itself
   
5. This means that 3000 sqm foundation area shall bear this load, which indicates that concrete load itself would be 42 cum each sqm, since only mat has been indicated to have been provided
   
6. Moreover, wind loads have not been primarily considered for computation of stresses, but seismic effects as advised on report due to implication of location zone code provision compliance
   
7. 钢筋的数量当然开掘d on complying with all requirements & not related an exclusively, to quantities of concrete, yet there is always certain pragmatic understanding pertinent reinforcing bars consumption on structures
   
8. Generally, on normal buildings, designed on working stress method, I have never experienced, on an average quantity of bars more than 170 kg each cum of RCC
   
9. All coefficients so high do not support such buildings, while heavier it being, itself goes against its primary requirement
   
10. I am certainly sure that data provided are erroneous somewhere
    
11. Moreover, no such data may be available on some projects after project is completed & no records are produced as built for quantities consumed
    
12. I remember one bid in UAE long back pertinent to one major project, which included 400000 cum of concrete for 120 km of water pipeline
    
13. I did not agree for that & challenged its volume
    
14. Nobody agreed since, work was done by one international joint venture
    
15. Surprisingly, when I received revised drawings after certain gap, quantities were reduced to 140000 cum
    
16. Therefore, it is experience of persons that can sometime tell by assessment that some data is not correct, which does not necessitate for justification production of certain evidence, while it should also, be considered that data are also, recorded by experienced persons if adequately authenticated
    
17. Every study cannot be assumed to be accurate, even if presented during international conference

[bijay sarkar]

Dear Sir,

As told by Suraj Sir, the data provided in my posting is based from practical field only. As you know, now a days, construction of 280 Meter high Chimney is frequent in India in Thermal Power Plnats. If we convert this height into stories considering 4m height of each storey, we get these chimneys are equivalent to 70 stories whereas we are discussing about a 56 storied building.

Again, Wind Tunnel Tests are conducted for Chimney as well as for Natural Draft Cooling Tower (NDCT) and accordingly analysed & designed. After getting information for many such chimneys all over India, we can have a natural idea of estimation, though may not be fully correct. But for the interest of discussion & data verification, we can take these data as a basis.

Moreover, if we search for the information of the latest tall buildings, we get that about 3,30,000 CUM concrete works and 39,000 MT reinforcing steel are consumed in Burz Khalifa. If anybody has any other data, may please submit.


with regards,

Bijay Sarkar

[suraj]

RCC material consumption
Dear Eng Bijay Sarkar
Burj

1. RCC 330,000 cum
   
2. Reinforcing bars 39000 T
   
3. Should your given figures be considered reliable, 1 cum concrete with about 120 kg Reinforcing bars has been used
   
4. When I constructed my house, I used 270 cum RCC with 23 T Reinforcing bars
   
5. I constructed about more than 600/650 sqm covered area including basement retaining walls & foundation beam frame
   
6. An ordinary framed building should not consume RCC more than 0.5 cum per sq m covered area
   
7. When, shear walls are included, quantity could be increased by say 25%, which means0.65 cum per sqm
   
8. 在预算估计初始阶段, RCC @ 0.5 cum per sqm is considered, while formwork varies between 4 to 6 depending on on section sizes

[gautam chattopadhyay]

can stacks be compared with multy storeyed buildings? geometry and internal floor arrangements are different in stacks. Multiple Flue duct stacks have window openings at various levels and need to be considered specially while analysing the shell of stack, manually or by software. Of course same MDOF system of computing natural frequency is applied to stacks also.

On Tue, Nov 27, 2012 at 11:29 AM, bijay sarkar forum@www.buonovino.com)> wrote:

[bijay sarkar]

Dear Sir,

Reinforcement Steel consumption in your residential building is about 85 kg/m3 of RCC. Consumption of such steel bars starts from machine foundations @70 kg/m3 of RCC and as you go higher, this parameter goes on increasing.

As we go higher and higher, at some point of time, we transit from strength based design into a deformation based design and we become more concerned about the drifts of different parts due to wind. For controlling such drifts due to height, we are penalised by spending more money in a steep slope against height....which is"Wind Premium"for such "Upmanship".


with regards,

bijay sarkar