@IDS Thank you for the response.
You're right. the "official sources" as we think they are, might also be wrong, but still my brain says what we did was not Eurocode expects us to do with that 0.00175 limit. The way we did it correct in calculation, so chart is in safe region, but the method...
@IDS Thank you for the response.
You're right, it makes no sense to compare the old chart of a book if the code is significantly changed.
However, how do we both know if yours and mine is correct if we do not compare it to a established chart?
Even both of our charts did not fully align with...
@IDS thank you for the response and the excel file.
However, I need a standard reference though. No need of latest charts, It's ok if the chart is old. Is there any old standard charts. I need official ones.
@IDS
Hi, is there any standard N-M interaction reference chart for Aus standards (for X axis atleast), so I can compare with mine as we did before for the eurocode chart?
The below is the N-M interaction chart for Eurocode for a biaxial concrete column.
Do Australian standards provide any guidance to come up with the N-M interaction diagram? Which clauses I need to look at if I want to make our chart compliant with AS 3600?
I want to know the calculations...
@IDS
Thank you for the response.
I have learned so much through the contributions from you and others in this thread. I believe now it's time to move into something else, but a related one. Will post a new thread for that.
Thank you so much 🤩
@EngDM
Thank you for the response,
The problem is, it even might not be a horizontal line at the end in that chart. If it is we can assume they applied a hard cap and rest of the line appeared perfect horizontal line. I believe, we actually did strain compatibility in the mid range up until...
@IDS Thank you for the response.
ChatGpt says (yeah, it's not a reliable source I know, should not even mention it here), something like we should use N = 0.00175 * x (d/x) , and it says we should consider each r/f bar's pure compression state, that means once NA moves away from the centroid...
@IDS
Thank you for the response.
I posted the same issue on some other websites to get it confirmed. I got some response from one of them saying that's not correct and 6.1 (5) is not applicable to columns. However, I don't get why it isn't related to columns as it's also a compression member.
@IDS
Thank you for the response.
Now it looks way better. But we're just force feeding the 0.00175 and we're over estimating the inbetween points in the pure compression. As I see it automatically skips the fine variations of the actual axial force and just connects with the position where M = 0.
I created this chart and the members of this forum made a great contribution towards it.
My chart aligns well until the pure compression, with the standard chart mentioned at "How to Design ConcreteStructures using Eurocode 2".
The problem is, it doesn't align when it enters the pure...
Is there any full calculation example of what you're saying, that shows the calculation of N and M in that pure compression? I don't get how to calculate that. The steps you mentioned doesn't make sense to me. So I need to see an example calculation, so I can understand what actually happens.
@IDS
Thank you for the response.
Yes you're right. They don't say that there should be a jump (or dip in my case). However, I still believe that dip/drop should be the limit of the axial force in the pure compression regardless of the method used like point C etc as the strain limit in pure...
@IDS
Can you please confirm this is only for steel strain calculations. As you said earlier we don't have to calculate the concrete strains as we take the concrete strains as uniform throughout the simplified compression block. So, I believe this is only for the steel?
It's bit confusing, in a...
Thank you for the response.
Now I get it.
What I still don't get is, how their chart is almost horizontal after the pure compression occurs. If they followed Eurocodes, there should be a drop as it caps at 0.00175 or 0.002. If their line is perfectly horizontal, we could have guessed they have...
I will prepare an individual excel sheet.
Mean while, can you please confirm if your chart below used the 0.9 reduction factor on fcd or it's without applying it?. When I remove the 0.9 reduction. My chart aligns with the standard chart. But when I apply it, it does not.
@IDS
Thank you for the response.
Further, my chart looks like it almost made it to the 0.4 line, but still not fully aligning. I'm confused how yours aligned when our calculations are the same. Please provide any suggestions to check to rectify this. What should I check?
@IDS
Thank you for the responses and the excel sheet. I'll go through it.
Apparently, you have disregarded the "reduced at pure compression" clause , and just introduced zero moments, just after column enters the pure compression. That's why your charts and standards charts have a horizontal...
