Structural Engineers Forum of India

SEFI General Discussion :: RE: The Great AI Heist of Structural Engineering Treasures

mkalgal — Tue, 30 Jun 2026 07:00:03 GMT

Author: mkalgal
Subject: The Great AI Heist of Structural Engineering Treasures
Posted: Tue Jun 30, 2026 7:00 am (GMT 0)

Excellent article Ms. Alpa. You have looked at the situation from all the angles
regards
Kalgal

***********************************�Dr. Manamohan R Kalgal
Benaka, 982, 13th Main, Srinagar,
BENGALURU - 560050, India
Ph.: +91 9844010074

On Mon, Jun 29, 2026 at 10:32 PM kedar_kavathekar <forum@sefindia.org (forum@sefindia.org)> wrote:

[quote] So true Sir ...

With Warm RegardsV P Kavathekar

On Mon, 29 Jun, 2026, 15:32 alpa_sheth, forum@sefindia.org (forum@sefindia.org))> wrote:

--auto removed--

Posted via Email

SEFI General Discussion :: RE: Development length calculation per ACI318 and IS codes

alpa_sheth — Mon, 29 Jun 2026 10:20:22 GMT
Author: alpa_sheth
Subject: Re: Development length calculation per ACI318 and IS codes
Posted: Mon Jun 29, 2026 10:20 am (GMT 0)

Hi,

You seem to be comparing the requirements of IS 456-2000 with ACI 318.
The requirements of IS 13920 are quite different. Refer Clause 7.1.1 The minimum width of the column into which a special moment resisting frame beam is passing through or anchoring into has to be  20 times  dia of the max dia of beam bar and not less than 300 mm. So if you have 32 dia bar in beam, the min width of the column would have to be 640 mm.
Hope this clarifies.

best regards,
Alpa Sheth
Jaya_kumar wrote:

Hello All,

I have been comparing the developed length for rebars in interconnected members per ACI318  section 25.4.3 vs Indian codes(SP34 or IS13920) that define the developed length for rebars.

ACI demands a certain distance of straight rebar from critical section. This is called Ldh. The hook (90⁰ or 180⁰) follows and it is of standard design. The hook length post the 90⁰ or 180⁰ bend does not factor in total developed length calculation.

So, for a rebar of certain size to have fully developed on a beam joining with that column, there is a minimum depth of column that needs to be provided. For example, with M20 concrete and Fe415 rebar, the minimum straight length of rebar ranges from 7inch to 12 inch based on other factors. So Ldh decides the width or depth of column when interfacing with another member.

However, in IS Code, the tension development length does not have a set straight length after critical section. All it requires is a certain length of rebar after critical section to meet the development length. That length can be before the 90⁰

For example, a FE550D grade 20mm rebar in M30 concrete we need about 50 times the dia of the rebar, which is 1000mm. If I'm able to provide 1000mm of rebar after critical section I can use this bar on any column depth from 9" to 1000mm.

For 9" column,the straight length after critical section may be about 6 inches, but the rest of 34 inches falls after the 90 degree bend.

Does this actually work in real life cases? Does the rebar after 90degree bend provide any meaningful resistance to the tension developed at critical section? Won't the concrete at the 90deg bend crush due to tension starting a brittle failure rather than a ductile failure?

I see often 20 or 16mm rebars are bent about 6-8" after the 90⁰ bend with not even providing the required Ld per IS Code, that too inside the 9" columns. What is the opinion of the engineers on this topic?

This is my first post, so kindly bear with me if I made any mistakes. Thank you all for your time.

SEFI General Discussion :: The Great AI Heist of Structural Engineering Treasures

alpa_sheth — Mon, 29 Jun 2026 09:42:35 GMT
Author: alpa_sheth
Subject: The Great AI Heist of Structural Engineering Treasures
Posted: Mon Jun 29, 2026 9:42 am (GMT 0)

Dear SEFIans,

You may have noticed that the discussions on SEFI and other international platforms for structural engineers  have quietened down a bit, even though the number of subscribers to SEFI are growing. This is because there is a belief (I think mistaken) that AI will be able to give us quicker responses than our fellow engineers on SEFI  in case of a str. engg. query one may have.

I know I typically go to an AI platform  for medical issues. And I must admit that the responses I get on ChatGPT or Perplexity or Claude seem very informed and are almost always aligned with the Doctor's diagnosis or medicine protocol. But  since AI is based on LLMs, it is hardly any surprise that it performs well in  in medicine; Many tasks in medicine  are pattern-recognition problems which AI can do very well. AI can read scans, flag anomalies, summarize records and much other stuff. Medical work often involves processing large amounts of text or lab data, which too are areas where AI performs well. That is why fields like radiology, pathology, etc. have been early beneficiaries of AI.

But it is erroneous for us to think that AI can perform just as well in Structural Engineering. Structural Engg does not necessarily lend itself as well to LLMs as Medicine does. Structural engineering is more constrained by physics, safety, and real-world validation. Structural engineering  needs exact compliance with codes, materials behavior, load paths, and so on. It is  much harder to automate in the AI straitjacket because Structural engineering decisions must hold up in the physical world and involve a lot of computation. While AI can assist with analysis and  design optimization,  the final responsibility still depends on engineering judgment, codes, and verification.

We have a curious situation  where as my colleague Sanjeev says, "Humans come less on SEFI while hundreds of AI bots attack us every day and want to eat up each byte  of data  humans created over decades to train their models. SEFI and likes are in great demand by AI models as food for one-time training." AI platforms know what  young engineers don't- it is a platform like SEFI that is  the true goldmine of structural engineering knowledge, fed as it has been by hundreds  of informed engineers  over thousands of hours across  than two decades.

The human- generated wealth of knowledge such as at SEFI has been consumed without permission- just simply stolen if I may, from across domains of knowledge by AI models. Anthropic AI admitted to consuming millions of paperbooks and once consumed,  destroyed physical copies and when copyright lawsuits happened,  they offered a measly $3000 per title. Imagine someone buying a book authored by you, and destroying its relevance and its need altogether by offering free knowledge learnt from that book which was your  lifetime's work.  An  AI  bot can scrape entire SEFI site within minutes and train it's neural networks while SEFI spent decades to create it.

Sites such as SEFI are being overtaken today by  AI sites in terms of traffic  because users get instant answers from AI rather than engaging with the community. But there is a catch. There will be, in all likelihood, a Kodak moment as they say.   The "Knowledge Cannibalization" Argument : A very real phenomenon sometimes called "Model Collapse" or the " *Data Exhaustion" problem is lurking around the corner.

There is a BIG RISK: If the community dies, the "training data" for future AI,  also dies. AI cannot easily learn new, unpatched software bugs or novel human theories if the forums where those are discussed become ghost towns. AI in structural engineering is dependent on its survival to sites like SEFI. But by  trying to making these forums redundant,  AI is essentially "eating its own tail." Without new human interaction, AI models will eventually start training on AI-generated content, which leads to a degradation in quality. New version of these models show no significant improvements over previous one due to data exhaustion... No new human generated knowledge.

I think it is time that all of us wake up to what's happening and reignite the creative, thinking engineer in us who survived without AI and will now survive, despite it and hand-in-hand with it.

warmly,
Alpa  Sheth

SEFI General Discussion :: Chloride and Sulphate content of soil and its testing

Jaya_kumar — Mon, 29 Jun 2026 02:23:12 GMT
Author: Jaya_kumar
Subject: Chloride and Sulphate content of soil and its testing
Posted: Mon Jun 29, 2026 2:23 am (GMT 0)

Hello All,

Do we have to conduct soil chloride and sulphate testing for foundation soil if the land is used for agriculture (coconut grove) for last 40 years using hard water up to 250 ppm? The water is generally low is chlorides (100ppm) and sulphates (50ppm) but I'm not if the soil accumulates chlorides and sulphates over time due to constant irrigation with hardwater, or the periodic monsoon rains wash them away into the soil.

I could not find any information on whether a soil chloride test is needed in this case or if this is a real concern at all.

Your valuable guidance and past experiences is greatly appreciated. Thank you.

SEFI General Discussion :: RE: Quick Poll: Ease of Use of BIS Codes in Structural Design

alpa_sheth — Fri, 26 Jun 2026 08:57:23 GMT
Author: alpa_sheth
Subject: Re: Quick Poll: Ease of Use of BIS Codes in Structural Design
Posted: Fri Jun 26, 2026 8:57 am (GMT 0)

My dear SEFIans,

C'mon have a cup of chai and take this 1 minute poll. I promise you, it won't take more than a minute. But let's show the SEFI Community in full strength by participating wholeheartedly.
The BIS Codes belong to all of us so together we need to participate in giving feedback. It goes a long way to the task of nation-building.

With warm regards,
Alpa Sheth

admin wrote:

Hello Sefians,

Hope all is going well and other than the heat, things are good with you!!

We have all been hearing the emphasis on "Ease of Doing Business" in our country for a while now. We thought that it would be a good idea, following the same principle, to initiate a conversation regarding "Ease of Use of Important BIS Codes in the Practice of Structural Design in India"

We request you to kindly participate in huge numbers in this one minute anonymous poll on ease of using BIS codes at this link (Google form) . We believe that this information will be immensely useful to the code-writers and Bureau of Indian Standards in the formulation of Codes. More importantly, it may show a way forward to BIS for getting feedback from the community before final issue of new or revised Codes for implementation.

Typically BIS issues codes for wide circulation before they are implemented. Potential users of the code are expected to give their feedback on the code. However the number of engineers who give feedback is miniscule. But when the code is implemented, there are loud concerns raised about difficulties in implementing the code, but it may then be a bit late by then or the code is unceremoniously withdrawn which is not a good precedent.

A poll such as the one being conducted will allow engineers to convey their views quickly to the concerned agencies, and in the long run, allow India to have codes which are easy to use and ensure safety and stability of the built environment.

Participate in the Poll Now

Help Spread the Word

Share this poll with your professional network to ensure the Bureau of Indian Standards hears the voice of the structural engineering community. Tap these links to share further.
<WhatsApp>WhatsApp || <LinkedIn>LinkedIn || <Twitter>Post <Facebook> Share

best regards,
SEFI Admin

SEFI General Discussion :: Crane Beam Design Web thk increase is failing the section

someshwar ganti — Mon, 22 Jun 2026 14:14:24 GMT
Author: someshwar ganti
Subject: Crane Beam Design Web thk increase is failing the section
Posted: Mon Jun 22, 2026 2:14 pm (GMT 0)

Hi all,
  I have been using Prabhakar sirs Crane Beam Design XLS sheet,

I found a typical case which I request seniors to clarify

I have a Girder section which was passing with 12 mm thk web
but the moment i made it 16 mm thk the design fails (in Prabhakar sirs xls),

unfortunately as Prabhakar sir is no more I cannot ask him to clarify or correct the BUG.

find attached my detailed explination how and why the design fails
I have made some assumptions, please correct me
in brief i have used
Clause  Cl. 8.4.2.1   d/tw > 67�ε  hence make the section semi compact
or
Table 2
Web is Plastic (d/tw ≤ 84�ε )  which makes it plastic

for tw = 16:
Zp usedβ_bMdz formulaMdz (kNm)
(Cl. 8.4.2.1) Zp_fl = 6 994 Ze/Zp = 1.63 Ze � fbd 2 055
(Table 2 only) Zp_full = 12 037 1.0 Zp_full � fbd 2 170
XLS ( the bug) Zp_fl = 6 994 1.0 ← wrong 1.0 � Zp_fl � fbd 1 261

i feel there is a Bug in prabhakar sirs program , I know many will not be having the program, but effectively it just calculating beta_b and which Zp  has to be taken (Full Zp or Only Zp of Flanges)

can anyone help me out

SEFI General Discussion :: RE: Field Engineering Talks on FB and Others

suraj — Sat, 20 Jun 2026 06:43:53 GMT
Author: suraj
Subject: Creation proposal of a new city INDIA TOWN in India
Posted: Sat Jun 20, 2026 6:43 am (GMT 0)

Creation proposal of a new city INDIA TOWN in India
Creation Proposal of a new city INDIA TOWN in India
https://www.facebook.com/pesuraj/posts/pfbid02WDQX5z6yKLe9bWpMz8ExwAiaHBEmSkHo7nQ1Bci1opiR7UCK5krjEJBTzFe4DbeGl

SEFI General Discussion :: Quick Poll: Ease of Use of BIS Codes in Structural Design

admin — Sat, 20 Jun 2026 05:00:07 GMT
Author: admin
Subject: Quick Poll: Ease of Use of BIS Codes in Structural Design
Posted: Sat Jun 20, 2026 5:00 am (GMT 0)

Hello Sefians,

Hope all is going well and other than the heat, things are good with you!!

We have all been hearing the emphasis on "Ease of Doing Business" in our country for a while now. We thought that it would be a good idea, following the same principle, to initiate a conversation regarding "Ease of Use of Important BIS Codes in the Practice of Structural Design in India"

We request you to kindly participate in huge numbers in this one minute anonymous poll on ease of using BIS codes at this link (Google form) . We believe that this information will be immensely useful to the code-writers and Bureau of Indian Standards in the formulation of Codes. More importantly, it may show a way forward to BIS for getting feedback from the community before final issue of new or revised Codes for implementation.

Typically BIS issues codes for wide circulation before they are implemented. Potential users of the code are expected to give their feedback on the code. However the number of engineers who give feedback is miniscule. But when the code is implemented, there are loud concerns raised about difficulties in implementing the code, but it may then be a bit late by then or the code is unceremoniously withdrawn which is not a good precedent.

A poll such as the one being conducted will allow engineers to convey their views quickly to the concerned agencies, and in the long run, allow India to have codes which are easy to use and ensure safety and stability of the built environment.

Participate in the Poll Now

Help Spread the Word

Share this poll with your professional network to ensure the Bureau of Indian Standards hears the voice of the structural engineering community. Tap these links to share further.
<WhatsApp>WhatsApp || <LinkedIn>LinkedIn || <Twitter>Post <Facebook> Share

best regards,
SEFI Admin

(Cl. 8.4.2.1)	Zp_fl = 6 994	Ze/Zp = 1.63	Ze � fbd	2 055
(Table 2 only)	Zp_full = 12 037	1.0	Zp_full � fbd	2 170
XLS ( the bug)	Zp_fl = 6 994	1.0 ← wrong	1.0 � Zp_fl � fbd	1 261