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vikram.jeet General Sponsor
Joined: 26 Jan 2003 Posts: 3835
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Posted: Thu Apr 08, 2021 1:49 pm Post subject: Proof checking - Always helped |
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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 General Sponsor
Joined: 26 Jan 2003 Posts: 3835
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Posted: Thu Apr 08, 2021 2:29 pm Post subject: |
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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 General Sponsor
Joined: 09 Nov 2009 Posts: 842
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Posted: Fri Apr 09, 2021 2:57 am Post subject: Proof Checking must be done on big projects . |
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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
Warning: Make sure you scan the downloaded attachment with updated antivirus tools before opening them. They may contain viruses. Use online scanners here and here to upload downloaded attachment to check for safety.
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Description: |
IAStructE document for proof checking . Not the full document . |
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IAStrcutE_Proof Checking (1).pdf |
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vikram.jeet General Sponsor
Joined: 26 Jan 2003 Posts: 3835
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Posted: Fri Apr 09, 2021 7:20 am Post subject: |
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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 General Sponsor
Joined: 26 Jan 2003 Posts: 3835
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Posted: Fri Apr 09, 2021 10:53 am Post subject: |
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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 General Sponsor
Joined: 26 Jan 2003 Posts: 3835
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Posted: Sat Apr 10, 2021 10:34 am Post subject: |
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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 General Sponsor
Joined: 26 Jan 2003 Posts: 3835
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Posted: Sun Apr 18, 2021 8:40 am Post subject: |
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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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vikram.jeet General Sponsor
Joined: 26 Jan 2003 Posts: 3835
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Posted: Tue Apr 20, 2021 12:00 pm Post subject: |
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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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vikram.jeet General Sponsor
Joined: 26 Jan 2003 Posts: 3835
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Posted: Wed Apr 28, 2021 8:39 am Post subject: |
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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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