TimSchrader2
Mechanical
- Feb 15, 2018
- 119
Been awhile since I used LRFD. A design "based on statistical analysis of probability of failure". Upon rereading I have several simple questions that I do not see readily in the searches. Pls respond if you know or have time. Thanks
1) It seems that this design should not be used for machines or mechanical design as these probabilities are not documented or easy to find. So asssumptions are made, which makes no sense to me. Is this design is mostly for buildings? Some say if the load factors are properly calibrated (Note this is done with ASD) then the results should be the same. Many disagree.
2) If the probablility of a certain size load ocurrance over a 10 year period is ???? percent, then the allowable stress (PER ASD) can be exceeded by the determined values. True? Some say you should not compare the two designs, but when all is said and done the saftey factor/Ultimate reistance load of the members or structure is either less or more.
Some say when the Live load < 3 times the DL dead load, that ASD is too or should i say more conservative. Which is my case by a large margin. And only if the operator makes a big mistake.
I have read or at least scanned several articles and can not find these simple answers. I still have my Blue AISC Steel Manual (7th ed).
Thanks
1) It seems that this design should not be used for machines or mechanical design as these probabilities are not documented or easy to find. So asssumptions are made, which makes no sense to me. Is this design is mostly for buildings? Some say if the load factors are properly calibrated (Note this is done with ASD) then the results should be the same. Many disagree.
2) If the probablility of a certain size load ocurrance over a 10 year period is ???? percent, then the allowable stress (PER ASD) can be exceeded by the determined values. True? Some say you should not compare the two designs, but when all is said and done the saftey factor/Ultimate reistance load of the members or structure is either less or more.
Some say when the Live load < 3 times the DL dead load, that ASD is too or should i say more conservative. Which is my case by a large margin. And only if the operator makes a big mistake.
I have read or at least scanned several articles and can not find these simple answers. I still have my Blue AISC Steel Manual (7th ed).
Thanks
