gnash68
Civil/Environmental
- Jul 14, 2008
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Hi All,
What is the percentage of error when designing a building using STAAD program?
What is the percentage of error when designing a building using STAAD program?
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STAAD 1
- Thread starter gnash68
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Compared to what?
1) Have you modelled it correctly?
2) How have you simplified it?
3) How representative are your loads?
4) What design assumptions did you make?
5) Did you model EVERYTHING?
Ther computer does the analysis based on the matrix stiffness method of analysis. To do this there are certain assumptions are used. The computer model is a tool. It will help you as an Engineer design something but it certainly does not replace you. You must use your judgement to determine if what the model is telling you seems reasonable. Do some parallel hand calculations to get a feel for the answer.
Even if take all the care in the world the results from your model will not tell exactly how the structure will behave. There are a number of reasons for this. The stiffness of the model will not be exactly the same as the structure in reality. The stresses calculated in members are probably incorrect as they do not take into account possible residual stresses in members. Your determination and application of loads is a simplification.
In essence there are so many possible variations and simplifications it is impossible to say something like STAAD is 97.65% accurate. The statement is meaningless.
1) Have you modelled it correctly?
2) How have you simplified it?
3) How representative are your loads?
4) What design assumptions did you make?
5) Did you model EVERYTHING?
Ther computer does the analysis based on the matrix stiffness method of analysis. To do this there are certain assumptions are used. The computer model is a tool. It will help you as an Engineer design something but it certainly does not replace you. You must use your judgement to determine if what the model is telling you seems reasonable. Do some parallel hand calculations to get a feel for the answer.
Even if take all the care in the world the results from your model will not tell exactly how the structure will behave. There are a number of reasons for this. The stiffness of the model will not be exactly the same as the structure in reality. The stresses calculated in members are probably incorrect as they do not take into account possible residual stresses in members. Your determination and application of loads is a simplification.
In essence there are so many possible variations and simplifications it is impossible to say something like STAAD is 97.65% accurate. The statement is meaningless.
MiketheEngineer
Structural
Agree - GIGO - garbage in - garbage out. The structural programs are all VERY acurate. I wrote some. It is the model that you develope that may cause a problem.
Make some simple calcs to verify that your model is accurate. Usually - I check reactions. Also - see if the deflections make sense.
Make some simple calcs to verify that your model is accurate. Usually - I check reactions. Also - see if the deflections make sense.
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- #4
Not to bash on any one program or start flame wars, but you may want to be extra careful with STAAD's results. There are a lot of quirks to the program and there are certain situations where I have run into a lot of marginally acceptable inaccurate results. But in principle I agree with Ussuri.
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