how to describe load step after using D command in transient analysis?

[mniki2007]

Hi every body
I had 1560 acceleration versus time data(ELCENTRO EARTHQUAKE DATA) and I wanted to do a transient analysis, after I saw more topics about seismic and transient analysis I understand that I have to convert my acceleration data to displacement so I use *VOPER and INT2 commands to do this and now I have displacement versus time data and I intend to do a transient analysis and using this data as displacement load at the base of my Structure, then I made a table using *Dim and set it as displacement load in my problem(D command),but I don't know how to set up my transient analysis option, do I have to describe separately a load step for every time and displacement data in solution control box in transient analysis? My data like this: time1, dis1 time2 dis2.......
Do I have to do like this: load step one?time1 dis1, load step two?time2 dis2…..?
If yes, how can I do this in ansys? Do I have to use APDL and do loop COMMAND to do this? Please explain it how?
Please write a sample APDL.
Second question:
the third frequency of my structure is 2.7414 and I want to set time step size ,is it correct that I use 1/20f as time step size ,and is it enough to solve the problem or I have to turn on automatic time steping and max and min time step size?
I want to do a transient analysis because of NON LINEARITY of my structure; do I have to set any setting in nonlinear tab of solution control box?
thanks

 

[mniki2007]

I intend to do a transient analysis and using dis versus time data as displacement load at the base of my Structure,I make a table using *Dim and set it as displacement load in my problem(D command),but I don't know how to set up my transient analysis option, do I have to describe separately a load step for every time and displacement data in solution control box in transient analysis? My data like this: time1, dis1 time2 dis2.......
Do I have to do like this: load step one-->time1 dis1, load step two-->time2 dis2…..?
If yes, how can I do this in ansys? Do I have to use APDL and do loop COMMAND to do this? Please explain it how?
Please write a sample APDL.

 

[mniki2007]

please help me if someone knows it.
thanks in advance
regard

 

[SKJoe]

Hi,

i wrote below a samle of code with basic setting, you must set another ones by yourself. Also set the minimum time increment (i set freq/200 for example) as you desire. In "node(x,y,z)" replace x,y,z with global coordinates of node for which is displacement value being applied.

freq = 2.7414
*dim, values,,1560,2

fini
/sol

antype,4

*do,i,1,1560
time , values(i,1)
nsubst, freq/20,freq/200,freq/20
d,node(x,y,z),,values(i,2),,,,ux
solve
*enddo

fini
/post26

Regards,
lubo

 

[mniki2007]

hi SKJoe
thanks alot for your response, i do every things that u said but again like my past problem when i check the result at nodes that I set the displacment load, there is difference between my load data and the data that shown in
post26 result plot.
I don't know why it happened,please help me why there is diffrence between them(load displacement and result displacement exactly on the same nodes).

thanks again
regards

 

[mniki2007]

hi SKJoe
thanks alot for your response, i do every things that u said but again like my past problem when i check the result at nodes that I set the displacment load, there is difference between my load data and the data that shown in
post26 result plot.
I don't know why it happened,please help me why there is diffrence between them(load displacement and result displacement exactly on the same nodes).

thanks again
regards