Direct Analysis Method training
Direct Analysis Method training
(OP)
Anyone know of who might be offering training on how to use the Direct Analysis Method in the new AISC code?
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Direct Analysis Method training
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RE: Direct Analysis Method training
RE: Direct Analysis Method training
RE: Direct Analysis Method training
The second order analysis must be carried out independently.
If using software, you must make sure it captures both P-capital delta and P-lower case delta effects. The commentary in the code gives two example problems that can confirm whether each of these effects is captured by the program.
In any case, you must add intermediate nodes in your members to ensure these effects are captured.
RE: Direct Analysis Method training
from page III-60.
"This method requires that both the flexural stiffness and axial stiffness be reduced and that 0.2% notational lateral loads be applied in the analysis. The combination of these two modifications account for the second-order effects and the results for design can be taken directly from the analysis."
RE: Direct Analysis Method training
The "No" applied to the first statement.
That is, you reduce both axial and flexural stiffness, apply notional loads (make sure to apply .003Yi in order to avoid using Tau factors), AND carry out a second order analysis (that captures both p-delta effect).
Sorry for the confusion.
RE: Direct Analysis Method training
RE: Direct Analysis Method training
RE: Direct Analysis Method training
RE: Direct Analysis Method training
k values don't come in anywhere in the Direct Analysis Method. Although that's not really related to the reduced stiffnesses.
RE: Direct Analysis Method training
I believe the commentary has some discussion about some factors that contribute to "non-ideal" conditions. These include:
-member out of plumb/manufacturing tolerances
-foundation not completely level
-temperature gradients causing non-uniform deflections
- etc.
Perhaps the reduced stiffness & lateral notational loads are to account for these factors; and the p-delta analysis is still performed to account for the p-delta effects (i.e. member deflection & joint translation), which are in addition to the effects listed above.
The advantage of the Direct Analysis Method is that K is always 1.0, therefore k values don't have to be determined.
RE: Direct Analysis Method training
You are right. It accounts for many of these effects. I simply meant that residual stresses are of primary concern.