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IS:801 -1975 - Design of Cold formed Sections
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chellappan_str
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PostPosted: Wed May 30, 2018 3:19 pm    Post subject: Reply with quote

Dear Mr. Alex,
This is the real question, in solar structure design,  people are considering only 1.3m as effective length to design the rafter which is totally wrong and there is no flange braces.
Need to have standard design practices.
_Thanks & Regards
Chellappan Annamalai
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akashgondhale966@gmail.co
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PostPosted: Thu May 31, 2018 7:30 am    Post subject: IS:801 -1975 - Design of Cold formed Sections Reply with quote

             We are designing the solar structure using Euro codes to check the Lateral buckling of thin gauge sections and as per the market since the IS:801 is not revised and there is no provision to check the lateral buckling but the Indian solar market designs are not checked for lateral buckling, most of the tenders are specified to use Indian Code in that case there is no provision to check the lateral buckling and there is lot of differences in terms of section sizes compare to staad design using IS: 801 and special software to use euro code, the stress ratios are 50% in IS:801 where as in Euro code it is 99% due to lateral buckling check. My question to the team here is when the IS: 801 is going to get revised and updated based on the International codes if not , the code should be withdrawn to safe guard of the structures. 
I can say answer to this question that IS 801 provides lateral-torsion buckling check but it is in the form of stress not the moment. The draw back of IS 801 is check for web crippling. It gives large value than actual value.


On Mon, May 28, 2018 at 1:36 AM, chellappan_str <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear Sir,
Greetings from Chellappan Annamalai to each and every member of Sefians,


I would like to know when the IS:801-1975 is going to get updated?
I need some clarifications on design of cold formed sections as per the following.

1) We are designing the solar structure using Euro codes to check the Lateral buckling of thin gauge sections and as per the market since the IS:801 is not revised and there is no provision to check the lateral buckling but the Indian solar market designs are not checked for lateral buckling, most of the tenders are specified to use Indian Code in that case there is no provision to check the lateral buckling and there is lot of differences in terms of section sizes compare to staad design using IS: 801 and special software to use euro code, the stress ratios are 50% in IS:801 where as in Euro code it is 99% due to lateral buckling check. My question to the team here is when the IS: 801 is going to get revised and updated based on the International codes if not , the code should be withdrawn to safe guard of the structures.

2) In staad there is no provision to check the effective length of top flange and bottom flange separately , for example in PEB building main frame design we used to keep the flange brace at the same purlin location, in that case when the nodes are created in staad to use the purlin loads and keep the common effective length of top and bottom flange. In solar structures the purlins are connected to the rafter in the top flange and the bottom flange is free but actual effective length should be taken the full length of the rafter but none of them are not considering. either the software should be revised to keep the provision for top flange effective length and the bottom flange effective length. need your views on this.

3) As per IS: 875 -Part-3 - 2015 ,for a mono sloped structures the CG of pressure should act as 0.3 W , W is the width of the solar structures, that means the load should be applied as uniformly varying load and not uniform loads. if we apply the uniform loads ( 0.5W) then the moment at the column is very less and when we compare the UVL load and UDL load the moment are vaying 50% more, there is no proper guidance to use IS:875-part-3 and solar Industry is doing on its own with out any control of the design basics. Need your views on this

4) The solar structures are supported by a single column in that case as per the end condition that is one end fixed and other end free end then the effective length should be 2L and none of the solar structures are not designed for that. This is against the principle of Strong Column & Weak Beam. Need your views on this.

5) Is there any guidance to design solar structures? at present building codes are used to design and the uplift forces are predominant and that too very less of 1.4T , in that case the supporting pile is it required to go with M20 concrete why cant be M15 or lesser? the compression forces are very much lesser say 1T. Need your views on this.

6) In IS:801-1975 the code clearly says to check combined bending and shear, the formulas are applicable only for single web sections that is C, Z, only and when we use HAT sections and U sections there will be double web in that case there is no provision in the code, how to design? at present we are using a special software as per euro code the hat sections can be designed but some times tender says the design should be based on IS:801 - 1975. Need your views on this.

7) Is there any committee is formed to revise the IS: 801 and also what kind of help/ guidelines can be given to the solar community to design the structures, due to the price pressures nowadays the tonnage for the Megawatt is shrinking down to 18T/MWp this is not a healthy design practices. Need your thought and help.

Cool Importance of panel braces and diagonal braces , as per IS-800-2007 clause 3.9.3 Wind and earthquake forces are reversible and
therefore call for rigidity and strength under force
reversal in both longitudinal and transverse directions.
To resist torsional effects of wind and earthquake
forces, bracings in plan should be provided and
integrally connected with the longitudinal and
transverse bracings, to impart adequate torsional
resistance to the structure. at present the solar Industry is ignoring the condition will leads to solar glass panel will get a crack, Need your views on this.

9) Lateral buckling is not depending on the strength of the material it is purely based on the sections sizes, as per IS:801 -1975 it is working stress method and also compare to euro codes where the load should be factored and checked for lateral buckling the effects are different. need your views.

Note: This is really a helpful topic to the Solar Industry to design the structure in a right way. Kindly help us.

- Thanks & Regards
Chellappan Annamalai
     



     


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PostPosted: Thu May 31, 2018 7:30 am    Post subject: IS:801 -1975 - Design of Cold formed Sections Reply with quote

Lateral buckling is not depending on the strength of the material it is purely based on the sections sizes, as per IS:801 -1975 it is working stress method and also compare to euro codes where the load should be factored and checked for lateral buckling the effects are different. need your views.
 Currently we are working on same topic i.e. how to avoid LTB of CFS beams and i am very lucky to have that work as my Master's project topic. Soon, we are going to have solution for this problem. 


On Mon, May 28, 2018 at 1:36 AM, chellappan_str <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear Sir,
Greetings from Chellappan Annamalai to each and every member of Sefians,


I would like to know when the IS:801-1975 is going to get updated?
I need some clarifications on design of cold formed sections as per the following.

1) We are designing the solar structure using Euro codes to check the Lateral buckling of thin gauge sections and as per the market since the IS:801 is not revised and there is no provision to check the lateral buckling but the Indian solar market designs are not checked for lateral buckling, most of the tenders are specified to use Indian Code in that case there is no provision to check the lateral buckling and there is lot of differences in terms of section sizes compare to staad design using IS: 801 and special software to use euro code, the stress ratios are 50% in IS:801 where as in Euro code it is 99% due to lateral buckling check. My question to the team here is when the IS: 801 is going to get revised and updated based on the International codes if not , the code should be withdrawn to safe guard of the structures.

2) In staad there is no provision to check the effective length of top flange and bottom flange separately , for example in PEB building main frame design we used to keep the flange brace at the same purlin location, in that case when the nodes are created in staad to use the purlin loads and keep the common effective length of top and bottom flange. In solar structures the purlins are connected to the rafter in the top flange and the bottom flange is free but actual effective length should be taken the full length of the rafter but none of them are not considering. either the software should be revised to keep the provision for top flange effective length and the bottom flange effective length. need your views on this.

3) As per IS: 875 -Part-3 - 2015 ,for a mono sloped structures the CG of pressure should act as 0.3 W , W is the width of the solar structures, that means the load should be applied as uniformly varying load and not uniform loads. if we apply the uniform loads ( 0.5W) then the moment at the column is very less and when we compare the UVL load and UDL load the moment are vaying 50% more, there is no proper guidance to use IS:875-part-3 and solar Industry is doing on its own with out any control of the design basics. Need your views on this

4) The solar structures are supported by a single column in that case as per the end condition that is one end fixed and other end free end then the effective length should be 2L and none of the solar structures are not designed for that. This is against the principle of Strong Column & Weak Beam. Need your views on this.

5) Is there any guidance to design solar structures? at present building codes are used to design and the uplift forces are predominant and that too very less of 1.4T , in that case the supporting pile is it required to go with M20 concrete why cant be M15 or lesser? the compression forces are very much lesser say 1T. Need your views on this.

6) In IS:801-1975 the code clearly says to check combined bending and shear, the formulas are applicable only for single web sections that is C, Z, only and when we use HAT sections and U sections there will be double web in that case there is no provision in the code, how to design? at present we are using a special software as per euro code the hat sections can be designed but some times tender says the design should be based on IS:801 - 1975. Need your views on this.

7) Is there any committee is formed to revise the IS: 801 and also what kind of help/ guidelines can be given to the solar community to design the structures, due to the price pressures nowadays the tonnage for the Megawatt is shrinking down to 18T/MWp this is not a healthy design practices. Need your thought and help.

Cool Importance of panel braces and diagonal braces , as per IS-800-2007 clause 3.9.3 Wind and earthquake forces are reversible and
therefore call for rigidity and strength under force
reversal in both longitudinal and transverse directions.
To resist torsional effects of wind and earthquake
forces, bracings in plan should be provided and
integrally connected with the longitudinal and
transverse bracings, to impart adequate torsional
resistance to the structure. at present the solar Industry is ignoring the condition will leads to solar glass panel will get a crack, Need your views on this.

9) Lateral buckling is not depending on the strength of the material it is purely based on the sections sizes, as per IS:801 -1975 it is working stress method and also compare to euro codes where the load should be factored and checked for lateral buckling the effects are different. need your views.

Note: This is really a helpful topic to the Solar Industry to design the structure in a right way. Kindly help us.

- Thanks & Regards
Chellappan Annamalai
     



     


Posted via Email
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akashgondhale966@gmail.co
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Joined: 26 Feb 2018
Posts: 8

PostPosted: Thu May 31, 2018 7:30 am    Post subject: IS:801 -1975 - Design of Cold formed Sections Reply with quote

Sir,   IS 801-1975 limits us to design section within limit of proportionality. Hence, DB is not considered in IS design guideline.


On Tue, May 29, 2018 at 11:11 AM, arulsteel <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear Rudraji

Yes you are very right. It neither deals with Distortional buckling (DB) nor elements under moment gradient. DB became a limit state of design recently after the new generation steels with 550 MPa YS and cold reduced steels which have US/YS ratio around 1.05.

We are trying to derive a simple distortional buckling equations for Indian designers. PFA a paper by us in the International Journal of Thinwalled structures. We are proposing to the BIS committee.

regards
arul IITM
     



     
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DB predictions for IS:801




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PostPosted: Thu May 31, 2018 7:30 am    Post subject: IS:801 -1975 - Design of Cold formed Sections Reply with quote

I think for DB ratio of (h/t) is limiting parameter. If h/t increases DB strength/resistance of section reduces which is given in (NAS)S100-16. 

On Thu, May 31, 2018 at 12:14 PM, Akash Gondhale <akashgondhale966@gmail.com (akashgondhale966@gmail.com)> wrote:
Quote:
Lateral buckling is not depending on the strength of the material it is purely based on the sections sizes, as per IS:801 -1975 it is working stress method and also compare to euro codes where the load should be factored and checked for lateral buckling the effects are different. need your views.
 Currently we are working on same topic i.e. how to avoid LTB of CFS beams and i am very lucky to have that work as my Master's project topic. Soon, we are going to have solution for this problem. 


On Mon, May 28, 2018 at 1:36 AM, chellappan_str <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear Sir,
Greetings from Chellappan Annamalai to each and every member of Sefians,


I would like to know when the IS:801-1975 is going to get updated?
I need some clarifications on design of cold formed sections as per the following.

1) We are designing the solar structure using Euro codes to check the Lateral buckling of thin gauge sections and as per the market since the IS:801 is not revised and there is no provision to check the lateral buckling but the Indian solar market designs are not checked for lateral buckling, most of the tenders are specified to use Indian Code in that case there is no provision to check the lateral buckling and there is lot of differences in terms of section sizes compare to staad design using IS: 801 and special software to use euro code, the stress ratios are 50% in IS:801 where as in Euro code it is 99% due to lateral buckling check. My question to the team here is when the IS: 801 is going to get revised and updated based on the International codes if not , the code should be withdrawn to safe guard of the structures.

2) In staad there is no provision to check the effective length of top flange and bottom flange separately , for example in PEB building main frame design we used to keep the flange brace at the same purlin location, in that case when the nodes are created in staad to use the purlin loads and keep the common effective length of top and bottom flange. In solar structures the purlins are connected to the rafter in the top flange and the bottom flange is free but actual effective length should be taken the full length of the rafter but none of them are not considering. either the software should be revised to keep the provision for top flange effective length and the bottom flange effective length. need your views on this.

3) As per IS: 875 -Part-3 - 2015 ,for a mono sloped structures the CG of pressure should act as 0.3 W , W is the width of the solar structures, that means the load should be applied as uniformly varying load and not uniform loads. if we apply the uniform loads ( 0.5W) then the moment at the column is very less and when we compare the UVL load and UDL load the moment are vaying 50% more, there is no proper guidance to use IS:875-part-3 and solar Industry is doing on its own with out any control of the design basics. Need your views on this

4) The solar structures are supported by a single column in that case as per the end condition that is one end fixed and other end free end then the effective length should be 2L and none of the solar structures are not designed for that. This is against the principle of Strong Column & Weak Beam. Need your views on this.

5) Is there any guidance to design solar structures? at present building codes are used to design and the uplift forces are predominant and that too very less of 1.4T , in that case the supporting pile is it required to go with M20 concrete why cant be M15 or lesser? the compression forces are very much lesser say 1T. Need your views on this.

6) In IS:801-1975 the code clearly says to check combined bending and shear, the formulas are applicable only for single web sections that is C, Z, only and when we use HAT sections and U sections there will be double web in that case there is no provision in the code, how to design? at present we are using a special software as per euro code the hat sections can be designed but some times tender says the design should be based on IS:801 - 1975. Need your views on this.

7) Is there any committee is formed to revise the IS: 801 and also what kind of help/ guidelines can be given to the solar community to design the structures, due to the price pressures nowadays the tonnage for the Megawatt is shrinking down to 18T/MWp this is not a healthy design practices. Need your thought and help.

Cool Importance of panel braces and diagonal braces , as per IS-800-2007 clause 3.9.3 Wind and earthquake forces are reversible and
therefore call for rigidity and strength under force
reversal in both longitudinal and transverse directions.
To resist torsional effects of wind and earthquake
forces, bracings in plan should be provided and
integrally connected with the longitudinal and
transverse bracings, to impart adequate torsional
resistance to the structure. at present the solar Industry is ignoring the condition will leads to solar glass panel will get a crack, Need your views on this.

9) Lateral buckling is not depending on the strength of the material it is purely based on the sections sizes, as per IS:801 -1975 it is working stress method and also compare to euro codes where the load should be factored and checked for lateral buckling the effects are different. need your views.

Note: This is really a helpful topic to the Solar Industry to design the structure in a right way. Kindly help us.

- Thanks & Regards
Chellappan Annamalai
     



     







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deepesh songara
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PostPosted: Tue Jun 05, 2018 3:30 pm    Post subject: IS:801 -1975 - Design of Cold formed Sections Reply with quote

Dear Sir,

I want to know about elastic 0r plastic cladding.


and solar panel has elastic property so why some of designer take it brittle cladding ( sapn/180) but it should be check by span /150 for purlin.  

Regards,
Deepesh Songara
Civil EngineerMobile: +918826882840Email: deepesh.songara04@gmail.com (deepesh.songara04@gmail.com)




















On Mon, May 28, 2018 at 1:36 AM, chellappan_str <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear Sir,
Greetings from Chellappan Annamalai to each and every member of Sefians,


I would like to know when the IS:801-1975 is going to get updated?
I need some clarifications on design of cold formed sections as per the following.

1) We are designing the solar structure using Euro codes to check the Lateral buckling of thin gauge sections and as per the market since the IS:801 is not revised and there is no provision to check the lateral buckling but the Indian solar market designs are not checked for lateral buckling, most of the tenders are specified to use Indian Code in that case there is no provision to check the lateral buckling and there is lot of differences in terms of section sizes compare to staad design using IS: 801 and special software to use euro code, the stress ratios are 50% in IS:801 where as in Euro code it is 99% due to lateral buckling check. My question to the team here is when the IS: 801 is going to get revised and updated based on the International codes if not , the code should be withdrawn to safe guard of the structures.

2) In staad there is no provision to check the effective length of top flange and bottom flange separately , for example in PEB building main frame design we used to keep the flange brace at the same purlin location, in that case when the nodes are created in staad to use the purlin loads and keep the common effective length of top and bottom flange. In solar structures the purlins are connected to the rafter in the top flange and the bottom flange is free but actual effective length should be taken the full length of the rafter but none of them are not considering. either the software should be revised to keep the provision for top flange effective length and the bottom flange effective length. need your views on this.

3) As per IS: 875 -Part-3 - 2015 ,for a mono sloped structures the CG of pressure should act as 0.3 W , W is the width of the solar structures, that means the load should be applied as uniformly varying load and not uniform loads. if we apply the uniform loads ( 0.5W) then the moment at the column is very less and when we compare the UVL load and UDL load the moment are vaying 50% more, there is no proper guidance to use IS:875-part-3 and solar Industry is doing on its own with out any control of the design basics. Need your views on this

4) The solar structures are supported by a single column in that case as per the end condition that is one end fixed and other end free end then the effective length should be 2L and none of the solar structures are not designed for that. This is against the principle of Strong Column & Weak Beam. Need your views on this.

5) Is there any guidance to design solar structures? at present building codes are used to design and the uplift forces are predominant and that too very less of 1.4T , in that case the supporting pile is it required to go with M20 concrete why cant be M15 or lesser? the compression forces are very much lesser say 1T. Need your views on this.

6) In IS:801-1975 the code clearly says to check combined bending and shear, the formulas are applicable only for single web sections that is C, Z, only and when we use HAT sections and U sections there will be double web in that case there is no provision in the code, how to design? at present we are using a special software as per euro code the hat sections can be designed but some times tender says the design should be based on IS:801 - 1975. Need your views on this.

7) Is there any committee is formed to revise the IS: 801 and also what kind of help/ guidelines can be given to the solar community to design the structures, due to the price pressures nowadays the tonnage for the Megawatt is shrinking down to 18T/MWp this is not a healthy design practices. Need your thought and help.

Cool Importance of panel braces and diagonal braces , as per IS-800-2007 clause 3.9.3 Wind and earthquake forces are reversible and
therefore call for rigidity and strength under force
reversal in both longitudinal and transverse directions.
To resist torsional effects of wind and earthquake
forces, bracings in plan should be provided and
integrally connected with the longitudinal and
transverse bracings, to impart adequate torsional
resistance to the structure. at present the solar Industry is ignoring the condition will leads to solar glass panel will get a crack, Need your views on this.

9) Lateral buckling is not depending on the strength of the material it is purely based on the sections sizes, as per IS:801 -1975 it is working stress method and also compare to euro codes where the load should be factored and checked for lateral buckling the effects are different. need your views.

Note: This is really a helpful topic to the Solar Industry to design the structure in a right way. Kindly help us.

- Thanks & Regards
Chellappan Annamalai
     



     


Posted via Email
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deepesh songara
SEFI Member
SEFI Member


Joined: 03 Mar 2018
Posts: 4

PostPosted: Tue Jun 05, 2018 3:30 pm    Post subject: IS:801 -1975 - Design of Cold formed Sections Reply with quote

Dear Sir,

I want to know about elastic 0r plastic cladding.


and solar panel has elastic property so why some of designer take it brittle cladding ( sapn/180) but it should be check by span /150 for purlin.  


Regards,
Deepesh Songara
Civil EngineerMobile: +918826882840Email: deepesh.songara04@gmail.com (deepesh.songara04@gmail.com)




















On Mon, May 28, 2018 at 11:06 PM, Rudra Nevatia <forum@sefindia.org (forum@sefindia.org)> wrote:
[quote]            Per my understanding, IS 801 does not cover distortional buckling and local buckling under stress gradient. This can lead to unsafe design.


Regards
Rudra Nevatia

On May 28, 2018 10:32 PM, "arulsteel" forum@sefindia.org (forum@sefindia.org))> wrote:       --auto removed--

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