About MultipleSupportExciatation

[Rocky]

There is no detail information in the help document.
I wonder if some one can give me some explaination
about the problem in my example. I will really appreciate
your help.

My example:

model basic -ndm 2 -ndf 3
node 1 0.0 0.0
node 2 0.0 3.0
fixY 0.0 0 1 1
mass 2 63.326 0.0 0.0
geomTransf Linear 1
element elasticBeamColumn 1 1 2 0.1 30000.0 3 1
recorder Node -file disp.txt -time -node 2 -dof 1 disp
recorder Element -file ele.txt -time -ele 1 force
set gaccel "Series -time {0.0 0.01} -values {0.0 10.0} -factor 1.0"
set gdispl "Series -time {0.0 0.01} -values {0.0 0.001} -factor 1.0"
pattern MultipleSupport 1 {
groundMotion 1 Plain -accel $gaccel
groundMotion 2 Plain -disp $gdispl
imposedMotion 2 1 1
imposedMotion 1 1 2
}
constraints Penalty 1.0e15 1.0e15
numberer RCM
system BandSPD
test EnergyIncr 1.0e-6 20 3
algorithm Newton
integrator Newmark 0.5 0.25
analysis Transient
analyze 1 0.01

[fmk]

if you are asking about the warning messages about obtaining vel from accel and then disp from vel and using the trapezoidal integrator to do all this .. the reason is that when using imposed motions the user SHOULD really specify the displacements (especially when using earthquake ground motions), as it is the displacements that are set at the nodes using single point constraints (not vel or accel).