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Reinforcement adopted for Test pile and working pile

 
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rajancivildesign@gmail.co
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Joined: 26 Jan 2011
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PostPosted: Wed Jun 01, 2011 9:04 am    Post subject: Reinforcement adopted for Test pile and working pile Reply with quote

Dear SAFIANS,
I have one doubt regarding adopting reinforcement for test pile and working pile.Routine test is conducted for 1.50 times the estimated safe load and may be used as working pile. But in case of Initial load test the pile has to be tested for twice the estimated safe load and not used for further loading. The percentage of reinforcement deponds mainly on the magnitude of testing load also. Some Engineers adopt the same reinforcement of testing pile  for  working  pile. In some cases they argued that it is not necessary to adopt  the test pile reinforcement for working pile as the with standing load differ for both cases. The test load mainly depends upon soil parameters not the reinforcement. Which is correct and what is folloed in practice. Kindly clarify with any literaure reference.
V.M.RAJAN.
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sspawar
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PostPosted: Wed Jun 01, 2011 9:44 am    Post subject: Reply with quote

DearnEngineer,
In practice no extra reinforcement are given for test piles.
If 1.5 times or 2 times loading is required then it will be meaningless if extra reinforcement will be provided.
Reference:
IS:2911 (Part4)-1985
Indian Standard
CODE OF PRACTICE FOR
DESIGN AND CONSTRUCTION OF
PILE FOUNDATIONS
PART 4 LOAD TEST ON PILES
(First Revision)
Fourth Reprint JANUARY 1997
UDC 624.154.1 : 624.042 : 006.76
0 Copyright 1985
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002
Gr5
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ibarua
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PostPosted: Mon Jun 06, 2011 8:34 am    Post subject: Reinforcement adopted for Test pile and working pile Reply with quote

6th June 2011

For routine tests, the test load is 1.5 times * computed safe load. In such condition, if the pile has been structurally designed by LSM with partial safety factor of 1.5, the section will reach limit state of collapse with fc = 0.4*fck and fst = 0.67* fy. However, if the test load is 2*computed safe load, then such section will go beyond limit state of collapse. Since the basic reason for load test is to check for settlement, it will not be desirable to allow the section to go sustain a load beyond limit state of collapse. Therefore, it will be necessary to provide such rebars that will limit concrete and steel stresses with 0.4*fck and 0.67*fy respectively at the test load.

Indrajit Barua.

On Wed, 01 Jun 2011 15:38:02 +0530 "rajancivildesign" <forum@sefindia.org> wrote
Quote:
           Dear SAFIANS,
I have one doubt regarding adopting reinforcement for test pile and working pile.Routine test is conducted for 1.50 times the estimated safe load and may be used as working pile. But in case of Initial load test the pile has to be tested for twice the estimated safe load and not used for further loading. The percentage of reinforcement deponds mainly on the magnitude of testing load also. Some Engineers adopt the same reinforcement of testing pile for working pile. In some cases they argued that it is not necessary to adopt the test pile reinforcement for working pile as the with standing load differ for both cases. The test load mainly depends upon soil parameters not the reinforcement. Which is correct and what is folloed in practice. Kindly clarify with any literaure reference.
V.M.RAJAN.
     
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gauravmaroo
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PostPosted: Mon Jun 06, 2011 9:37 am    Post subject: Reply with quote


Dear Sir
If we follow IRC 78 code clauses than following are my observations on your topic

Test pile if acting in a group than no horizontal test is required...horizontal test is required only if pile is acting singly.....test load prescribed in IRC 78 is 2.5 times...and the pile shall be designed to carry the test load as per code.....test condition for free standing pile can be free head while for land pile it can be fixed head....

Test pile can be designed by ultimate load theory as we are not going to use it again after testing...hence material stresses can be un-factored...

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vikram.jeet
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PostPosted: Tue Jun 07, 2011 5:39 am    Post subject: Reinforcement adopted for Test pile and working pile Reply with quote

As personal opinion (subject to review)

Testing of pile serve both functions i.e. - -  
(i) Testing the settlement of pile  

(ii) testing the structural strength at ultimate load of 2*P which can be indicator of
actual strength of constructed pile and directly reflect the construction Quality


FOS in limit design combining Load factors and partial safety factors of materials
The total FOS under limit design = 1.5*1.5 = 2.25 (for concrete)
The total FOS under limit design = 1.5*1.15 = 1.725 (for reinf)
Net FOS = 2.25*99.6/100+1.725*0.4/100=2.2479 which is > 2.0
(assuming 0.4% reinf in piles)

Hence the pile will be subject to test on both counts

The test of structural strength of constructed pile may also be the reason along
with settle ment of pile for taking a load of 2.0*P as test load

Hence a test pile needs to be tested with same reinf as other piles to assess
its capacity from both counts.

best regds

vikramjeet


6th June 2011
For routine tests, the test load is 1.5 times * computed safe load. In such condition, if the pile has been structurally designed by LSM with partial safety factor of 1.5, the section will reach limit state of collapse with fc = 0.4*fck and fst = 0.67* fy. However, if the test load is 2*computed safe load, then such section will go beyond limit state of collapse. Since the basic reason for load test is to check for settlement, it will not be desirable to allow the section to go sustain a load beyond limit state of collapse. Therefore, it will be necessary to provide such rebars that will limit concrete and steel stresses with 0.4*fck and 0.67*fy respectively at the test load.
Indrajit Barua.
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Damodara Bhat
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PostPosted: Mon Aug 10, 2020 3:53 pm    Post subject: Re: Reinforcement adopted for Test pile and working pile Reply with quote

rajancivildesign@gmail.co wrote:
Dear SAFIANS,
I have one doubt regarding adopting reinforcement for test pile and working pile.Routine test is conducted for 1.50 times the estimated safe load and may be used as working pile. But in case of Initial load test the pile has to be tested for twice the estimated safe load and not used for further loading. The percentage of reinforcement deponds mainly on the magnitude of testing load also. Some Engineers adopt the same reinforcement of testing pile  for  working  pile. In some cases they argued that it is not necessary to adopt  the test pile reinforcement for working pile as the with standing load differ for both cases. The test load mainly depends upon soil parameters not the reinforcement. Which is correct and what is folloed in practice. Kindly clarify with any literaure reference.
V.M.RAJAN.
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