Hi,
I have to perform steady state dynamic analysis in frequency domain of a steel structure supporting two different compressors with different operating speeds.
I have unbalance loading, which is varying with square of machine frequency.
Question: Can I perform dynamic analysis of structure which is supporting different operating speed machines whose unbalance loading is varying with square of speed.
What would be the possible command for dynamic analys in staad since there are different operating speed machines?
The format of applying dynamic load is as below as per staad help is as follows:
Machine 1:
BEGIN HARMONIC FORCEFREQUENCY FLO 1 FHI 80 NPT 5 MODALHARMONIC FORCE DAMP 0.03JOINT LOAD PHASE Z 0 Unit KNS927 FZ 0.00028AMPLITUDE Z A 1 B 0 C 0PRINT HARMONIC DISPLACEMENT LIST 14 20 21 28 29 923 924 927 TO 931 -934 TO 937 942 943 950 TO 952
Machine 2:
BEGIN HARMONIC FORCEFREQUENCY FLO 1 FHI 200 NPT 5 MODALHARMONIC FORCE DAMP 0.03JOINT LOAD PHASE Z 0 Unit KNS930 FZ 0.000106AMPLITUDE Z A 1 B 0 C 0PRINT HARMONIC DISPLACEMENT LIST 14 20 21 28 29 923 924 927 TO 931 -934 TO 937 942 943 950 TO 952
Machine 3:
BEGIN HARMONIC FORCEFREQUENCY FLO 1 FHI 36 NPT 5 MODALHARMONIC FORCE DAMP 0.03JOINT LOAD PHASE Z 0 Unit KNS931 FZ 0.000106AMPLITUDE Z A 1 B 0 C 0PRINT HARMONIC DISPLACEMENT LIST 14 20 21 28 29 923 924 927 TO 931 -934 TO 937 942 943 950 TO 952
someone to help on this plz
Are the two machines with different operating speeds and frequency operating simultaneously (i.e acting at same instance of time)?
Yes, both machines working simultaneously..
Then in my view two separate STAAD.Pro models could be created (one for each machine) because at a time in Steady State Analysis module one particular frequency is applied over entire structure. You could then manually combine the response as required (maybe in an excel file) and find out the response in your structure due to both machines acting simultaneously.
could i ask how to combine the results from two separate analyses? using SRSS or directly summarizing the results at same frequency?