How does the start time in a THL file affect code stress occasional results ?
The Start time column specifies time at which the time history wave is hitting a bend. Then the time history profile loads and duration are applied to a bend.
Example: Using AutoPIPE Example model Apham1.dat
Original THL data from "W1" transient: Notice the start time (ex. 0.005 sec) that a History Profile (ex. W1C12) was applied to a node point (ex. C12)
Respective History Profiles:
Plot the actual time line from Time = 0 to the end of the transient:
Now change the Start time as shown below and re-plot the results
Magnitude and number of loads applied in the 2 total time profiles has not change. The only variable changed was Start Time. Referring to the original time profile, noticed how one or more loads can act simultaneously on the piping system. However, when the start time was increased, only one load maybe applied to the piping system at any given time.
Again, inaccuracy of applying time history profiles at their respective locations can have a profound affect on the loading and ultimately all results where time history load cases are considered.
Because of the way a Slug flow analysis is defined, similar forcing functions & 2x as many entries in the THL file, results may not be as adversely affected by Start Time changes as noted above.
Dynamic "Time History" Analysis