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Proof checking - Always helped

 
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vikram.jeet
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PostPosted: Thu Apr 08, 2021 1:49 pm    Post subject: Proof checking - Always helped Reply with quote

To err is human , to correct is Divine

The proof checking of designs done by prime consultant and checked by proof check consultant always helped the both parties  and also the client engg. Wing.
Bridge design & drgs were always proof checked by earlier Ministry of Surface Transport design wing for bridges on National Highways AND respective PWD's for state hways. There were exchange of technical views and was source of learning.
For Water treatment plants & sewage treatment plants ,Pumping stations of water supply , sewage, OH water tanks, and other design fields were also proof checked.  Building designs were sent to IIT's for checking.

Proof checking gives immense opportunity to learn, express  and correct.

Proof checking must be encouraged in all designs .
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vikram.jeet
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PostPosted: Thu Apr 08, 2021 2:29 pm    Post subject: Reply with quote

Some instances of proof checking

Design of cw reservoir of size 90mx50m fully under ground.rcc columns were at about 2.5m c/c, top slab & base slab designed as flat slabs , there was earth overburden of about 1 .5 m on top slab  to counter uplift pressure.
Designs done manual
Side walls - base width was 600mm & top width of column 300 mm
Walls are designed as propped cantilever hinged at top.
Walls were designed without considering non prismatic
aspect i.e. walls are of varying section along span.
Earth pressure was taken as active EP

Proof checker comments :
Walls must be designed considering non prismatic . This rental ed in higher BM at base and was also seen by proof checker on computer using some in house software.
Earth pressure must be taken as EP rest.as wall is not a free cantilever and hingedvat top. Value of EP was taken as (1 - sin phi) instead of Ka.

Proof checking helped
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VPandya
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PostPosted: Fri Apr 09, 2021 2:57 am    Post subject: Proof Checking must be done on big projects . Reply with quote

Dear Er Sri Vikram.jeet ,

This topic of PROOF CHECLKING is related to PUBLIC SAFETY . Some cities in USA have made it mandatory  to have PROOF CHECKING ( PEER REVIEW ) done before city issue construction permit .  BOSTON and CHICAGO and some other cities in USA require a  Proof Checking before they issue a construction permit for the Project.

Cities in USA have learned it HARD WAY  to  require  proof  checking after some major Structural Collapses in their cities .  It was not there before .

This document ( Attached ) may be helpful in doing proof checking .


Regards .


Vasudeo Pandya  P.E.
Structural Engineer



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IAStrcutE_Proof Checking (1).pdf
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IAStructE document for proof checking . Not the full document .

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vikram.jeet
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PostPosted: Fri Apr 09, 2021 7:20 am    Post subject: Reply with quote

Dear Shri Vasudeo Pandya sir,

Your valuable experience of working in US & other International arena clearly tells the importance of proof checking of structural & civil designs . As one & one makes eleven , the value addition provided  in the process by the consultants have inumberable benefits at cost of little expenses.

Indian Clients still try to avoid the proof checking expenses , but there is need to convince them about the benefits vis a vis expenses.

However it is seen that Govt Departments are inclined to appoint their proof checking Consultants for major projects. If These Deptts have their expertise , checking is done in-house.

Thanks for uploading the document for benefit of one & all.

Best regards

vikramjeet
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vikram.jeet
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PostPosted: Fri Apr 09, 2021 10:53 am    Post subject: Reply with quote

As a design reviewer -

A design of OH water tank done by a consultant was proof checked with following major observation (  apart from other comments)
The e OH tank was of capacity around 1.5 lakh litres and staging htof 20m. It was supported on staging of three columns.

It was advised to provide at least 4 nos column staging. Reference of IS 11682 reg design of rcc staging for OH water tanks was provided to convince.
As per IS 11682 ,OH tanks of capacity greater than 50000 liters must have at least 4 columns staging.
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vikram.jeet
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PostPosted: Sat Apr 10, 2021 10:34 am    Post subject: Reply with quote

Proof checking of Subway design

The subway was provided with retaining rcc walls and rcc columns in main hall of Subway . Traffic class 70R. Subway under 3+3+central verge road junction of T crossing. Subway for pedestrians moving in all four direction.

The designer presented the designs .It appeared that designs were done following more of IS code  thanIRC codes at that some 25 yrs back. Presentations of manual calcs was very shabby. Then designer was called and explained the need for putting up calcs in a way easily understandable ,  for which he was convinced.
The rcc slab was beam & slab type arrangement. The designer has taken dispersion of IRC loads  in beam design as well as slab design.
For design of slabs ,the dispersion of wheel loads is allowed by IRC, but it was commented that dispersion shall not be taken for design of beams. The IRC codal stipulation was  referred for satisfaction of prime designer.
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vikram.jeet
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PostPosted: Sun Apr 18, 2021 8:40 am    Post subject: Reply with quote

Responsibility of design/ drgs

Prime consultant's design/drgs  are checked by  the proof consultant / or  inhose  vetted by Owner having its own design department, be it Govt or Pvt organisation.

It was  seen that  after checking of designs , the drgs were stamped by the proof reader in various categories of approval  plus giving a footnote stating that The Approval conveyed herein do not relieve the contractor and prime consultant of correctness of dimensions, design , analysis , materials etc etc.

Even earlier Bridge designs checked by Ministry of Surface Transport were stamped on all drgs about the responsibility on the  prime consultant & contractor.

There are no guidelines . In a Delhi metro pier cap(cantilever) collapse during construction stage , the Client black listed prime consultant for five years and a renowned proof consultant for three yrs.

But still proof checking consultants feel that their role is advisory in nature  and must be provided imunity if an issue arises.
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PostPosted: Tue Apr 20, 2021 12:00 pm    Post subject: Reply with quote

Net diameter to be used for bolts


On proof checking in past, it was found that in steel  sheds , PEB 's , the diameter of bolt used in design happened to be gross diameter.

It was asked to be corrected to net diameter at threading . Generally net  bolt xsec area is 75% to 80% of gross  bolt area and nos of bolts requirement be decided accordingly.
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PostPosted: Wed Apr 28, 2021 8:39 am    Post subject: Reply with quote

Just a proof check of drgs of some Charitable  place in non metro. Area

It was found the reinforcements etc are nearly 70% of requirements.
Designer was a mechanical engineer giving free service as charity. He used stresses of steel reinforcements as 0.87 fy, but loading was taken as working loads. He argued too much when he was asked to use a load factor of 1.5 with loading. He lectured that designs are heavy because of these factors.

Such situations  are painful .
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