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[k.gangadharan]

NECESSITY for an EXPLANATORY part to Is 16700 / 2017

 
In IS codes 1893/2016, 13920/2016 and IS 875 part 3 /2015 and the new code 16700/2017,  most of the provisions are inter connected. Some of the clauses in 16700 is confusing with the provisions of the other codes mentioned above .

Generally speaking ,therefore,  in my opinion,  an explanatory addition to 16700/2017 , in the form of a Special publication,is necessary , interpreting the various clause to understand this new code  fully ,and adapt for practical application.

CLAUSE 9.4 , depth of foundation

It is stated that the ebedded depth of foundation, shall be the least of  1/5 of the ht. of bldg. in RAFT foundation and 1/20 of the ht of bldg for piled & piled Raft buildings.

If you examine some of the already constructed tall bldgs , this clause is not observed .

For example Burg Khalifa  in Dubai is 828 m high bldg and It is on a piled raft foundation; the pile cap is 3.7 m thick & the piles are 150mm dia and 43 m long and there are 193  such piles & they are not found on rock and is found on dense sandAand supported in the naturally cement cancisiltite conglomeric formations. As per per Cl. 9.4 this building must have an embedment of 828/ 20 embedment length i.e 42 meter below ground level. This  means that this building should have a min: of 10 or 12 floors below gr. level. Actually It has a few parking floors.

If you examine some of the other tall buildings already constructed elsewhere also, this is not a requirement . In my  opinion 1/15 & 1/20 is not a relevant figure for embedment legth and it may not be practical to provide such length in tall & supertall buidings.


Another important requirement in Tall Buildings is DAMPERS. 

This aspect has not been mentioned or highlighted in this code.

In almost all tall builngs, already constructed ,different types of dampers have been used to reduce drift ,lateral deflection and vibrations due to dynamic wind loads.

There are positive Visco Elastic dampers, Tuned Mass dampers, Sloshing Warer Damoers, Tuned Liquid Dampers and Simple Pedulum dampers. Most of the Tall & super tall bldgs. already constructed have  used one or other types of dampers.

This aspect needs inclusion in the new code.

thanks & regards

Gangadharan.k

structural consultant

 

Posted via Email

[Indra Nath Mishra]

Dear Sir, FYI & N/A pls.





Regards,
I.N.Mishra





On Saturday, 17 March, 2018, 12:52:22 PM IST, k.gangadharan <forum@sefindia.org> wrote:




           NECESSITY for an EXPLANATORY part to Is 16700 / 2017


In IS codes 1893/2016, 13920/2016 and IS 875 part 3 /2015 and the new code 16700/2017, most of the provisions are inter connected. Some of the clauses in 16700 is confusing with the provisions of the other codes mentioned above .

Generally speaking ,therefore, in my opinion, an explanatory addition to 16700/2017 , in the form of a Special publication,is necessary , interpreting the various clause to understand this new code fully ,and adapt for practical application.

CLAUSE 9.4 , depth of foundation

It is stated that the ebedded depth of foundation, shall be the least of 1/5 of the ht. of bldg. in RAFT foundation and 1/20 of the ht of bldg for piled & piled Raft buildings.

If you examine some of the already constructed tall bldgs , this clause is not observed .

For example Burg Khalifa in Dubai is 828 m high bldg and It is on a piled raft foundation; the pile cap is 3.7 m thick & the piles are 150mm dia and 43 m long and there are 193 such piles & they are not found on rock and is found on dense sandAand supported in the naturally cement cancisiltite conglomeric formations. As per per Cl. 9.4 this building must have an embedment of 828/ 20 embedment length i.e 42 meter below ground level. This means that this building should have a min: of 10 or 12 floors below gr. level. Actually It has a few parking floors.

If you examine some of the other tall buildings already constructed elsewhere also, this is not a requirement . In my opinion 1/15 & 1/20 is not a relevant figure for embedment legth and it may not be practical to provide such length in tall & supertall buidings.


Another important requirement in Tall Buildings is DAMPERS.

This aspect has not been mentioned or highlighted in this code.

In almost all tall builngs, already constructed ,different types of dampers have been used to reduce drift ,lateral deflection and vibrations due to dynamic wind loads.

There are positive Visco Elastic dampers, Tuned Mass dampers, Sloshing Warer Damoers, Tuned Liquid Dampers and Simple Pedulum dampers. Most of the Tall & super tall bldgs. already constructed have used one or other types of dampers.

This aspect needs inclusion in the new code.

thanks & regards

Gangadharan.k

structural consultant

Posted via Email

[Pulkit Velani]

Dear Sir,

With due respect I would like to say regarding CL 9.4: The point you raised might be valid or need discussion, however, the example given by you for Burj Khalifa is not valid since maximum height of building consider as per IS 16700:2017 is 250 m only. Hence maximum embedded depth coming to be: Raft=16.6m (H/15) and Pile=12.5m(H/20).  

regards,
Pulkit

[ssankaran]

Well said. Embedment depth can only be suggestive and not mandatory.S Sankaran


On 17-Mar-2018 12:50 PM, "k.gangadharan" <forum@sefindia.org (forum@sefindia.org)> wrote:

[dipak_bhattacharya]

Dear moderators,

Whether depth of embedments have been appropriately defined in the new code IS 16700.


Though , in case of Raft foundations, embedments may be upto bottom of raft, what should be depth of embedment for buildings based on piled foundations, whether it should be upto bottom of pile caps or upto the ends pf pile lengths.


Regards,


Dipak Bhattacharya / Delhi.


On 17 March 2018 at 12:50, k.gangadharan <forum@sefindia.org (forum@sefindia.org)> wrote: