| Applies To | |
| Product(s): | AutoPIPE |
| Version(s): | ALL; |
| Area: | |
| Date Logged & Current Version | Nov 2019 12.02.00.14 |
Problem:
How are the moments in the Code Compliance report calculated based on different combination methods (ex. ABS, SRSS, etc..) ?
Example:
Solution:
Note: This is just an example problem to illustrate how the results are calculated and not promoting the combinations being created.
Given the following modeling information, how are the moments calculated at A01 and A05?:
Question: For node point A01, what moments should be used in calculating the reported Mb values for code combinations ABS(1155 N*m) and SRSS(1155 N*m):
a. Code Combination E1, E2, E3 values in column labeled Mb
or
b. Non-code combination E1, E2, E3 values from Forces and moments sub-report
Answer: If you selected A, you are wrong! The values used to calculated the values reported in columns Ma, Mb, or Mc of the Code Combinations are based on values from the Non-code combinations sub-report Forces and Moments.
Example:
Calculate Mb for give combination at indicated node point:
Node point A01 | |
ABS:X-axis Mx = ABS [Mx (E1)] + ABS [Mx (E2)] + ABS [Mx (E3)] Mx = ABS [0] + ABS [0] + ABS [817] Mx = 817 Y-axis Mx = ABS [My (E1)] + ABS [My (E2)] + ABS [My (E3)] Mx = ABS [0] + ABS [0] + ABS [0] My = 0 Z-axis Mx = ABS [Mz (E1)] + ABS [Mz (E2)] + ABS [Mz (E3)] Mx = ABS [817] + ABS [0] + ABS [0] Mz = 817
Mb = SQRT (Mx^2+My^2+Mz^2) Mb = SQRT (817^2+0^2+817^2) Mb = 1155 compare value to output report, OK |
SRSS:X-axis Mx = SQRT{ [Mx (E1)]^2 + [Mx (E2)] ^2 + [Mx (E3)]^2 } Mx = SQRT{ [0]^2 + [0] ^2 + [817]^2 } Mx = 817 Y-axis My = SQRT{ [My (E1)]^2 + [My (E2)] ^2 + [My (E3)]^2 } My = SQRT{ [0]^2 + [0] ^2 + [0]^2 } My = 0 Z-axis Mx = SQRT{ [Mz (E1)]^2 + [Mz (E2)] ^2 + [Mz (E3)]^2 } Mx = SQRT{ [817]^2 + [0] ^2 + [0]^2 } Mx = 817
Mb = SQRT (Mx^2+My^2+Mz^2) Mb = SQRT (817^2+0^2+817^2) Mb = 1155 compare value to output report, OK! |
Node point A05 | |
ABS:X-axis Mx = ABS [Mx (E1)] + ABS [Mx (E2)] + ABS [Mx (E3)] Mx = ABS [-5] + ABS [295] + ABS [399] Mx = 699 Y-axis Mx = ABS [My (E1)] + ABS [My (E2)] + ABS [My (E3)] Mx = ABS [346] + ABS [18] + ABS [-12] My = 376 Z-axis Mx = ABS [Mz (E1)] + ABS [Mz (E2)] + ABS [Mz (E3)] Mx = ABS [-5] + ABS [163] + ABS [16] Mz = 184
Mb = SQRT (Mx^2+My^2+Mz^2) Mb = SQRT (698^2+377^2+183^2) Mb = 815 compare value to output report, OK |
SRSS:X-axis Mx = SQRT{ [Mx (E1)]^2 + [Mx (E2)] ^2 + [Mx (E3)]^2 } Mx = SQRT{ [-5]^2 + [295] ^2 + [399]^2 } Mx = 496 Y-axis My = SQRT{ [My (E1)]^2 + [My (E2)] ^2 + [My (E3)]^2 } My = SQRT{ [346]^2 + [18] ^2 + [-12]^2 } My = 347 Z-axis Mx = SQRT{ [Mz (E1)]^2 + [Mz (E2)] ^2 + [Mz (E3)]^2 } Mx = SQRT{ [-5]^2 + [163] ^2 + [16]^2 } Mx = 164
Mb = SQRT (Mx^2+My^2+Mz^2) Mb = SQRT (817^2+0^2+817^2) Mb = 627 compare value to output report, OK! |
Conclusion:
The program does consideration the selected combination method when calculating the moments Ma, Mb, and Mc. When trying to verify these results, be sure to use the correct equations and moments otherwise the hand calculated results will not match the reported values from AutoPIPE.
In this example combinations ABS and SRSS results were found to be identical at A01 (Mb = 1155), At first this seems to be cause for concern, however can easily be explained by looking at the hand calculations. This was only possible because of the anchor at node point A03 N, and seismic loads E1 & E3 produced identical moments because of that anchor in the vertical piping.