Bi-directional acceleration

[MPazidis]

Hello,

I am conducting some tests on a simple 2D fixed-base SDOF system.
I am trying to run the analysis for two (2) simultaneous UniformExcitation Patterns; one of them being a translational time-history acting on direction (1) (X) and the other being rotational around axis (3) (Z).
After running the analysis though, the recorded results seem to be only due to the translational motion and not for the combination of both and I cannot understand why. I am posting the script for reference.


################## START ####################
wipe
model basic -ndm 2 -ndf 3;
set M2 1.0
set dt 0.01
set E 1000.0
set A 1.0
set Iz 0.1

node 1 0.0 0.0
fix 1 1 1 1

node 2 0.0 2.0
mass 2 $M2 1.e-9 1.e-9

geomTransf Linear 1
element elasticBeamColumn 1000 1 2 $A $E $Iz 1

recorder Node -file M2_disp.out -time -dT $dt -node 2 -dof 1 2 3 disp
recorder Node -file M2_accel.out -time -dT $dt -node 2 -dof 1 2 3 accel

set Utr FIMtrans.out ; # translational motion
set Urot FIMrotLONG.out ; # rotational motion

timeSeries Path 100 -dt 0.01 -filePath $Utr
timeSeries Path 101 -dt 0.01 -filePath $Urot

pattern UniformExcitation 1 1 -accel 100; # create Uniform excitation
pattern UniformExcitation 2 3 -accel 101; # create Uniform excitation


# analysis objects
constraints Plain
test NormDispIncr 1e-4 25 0
algorithm ModifiedNewton
numberer RCM
system BandGeneral
rayleigh 0.5712 0.001447 0. 0.
integrator Newmark 0.5 0.25
analysis Transient
analyze 2500 $dt
puts "done"
wipe
################## END ####################

[MPazidis]

Disregard my previous post, it seems that I made a mistake in the OpenSees-Matlab interaction. I am sorry
Although, I would still like to know what combination rule OS uses in order to calculate the response (Linear, SRSS, CQC)

[selimgunay]

There is no combination rule used as OpenSees does a direct time integration analysis (i.e solve the MDOF dynamic equations of motion using a time integration method) and not a modal response analysis.

[Hwoarang]

Hi everyone

I want to run a nonlinear time history analysis. But I want to apply both longitudinal and transversal accelerations simultaneous. I have done that this way. Is that true?

set iGMfact "1.82 1.82"; # ground-motion scaling factor
set iGMdirection "1 3"; # ground-motion directions

set Records {ImperialValley Victoria LomaPrieta1 LomaPrieta2 Northridge ChiChi Manjil HectorMine Iwate1 Iwate2 Darfield}

set LRecords {ImperialValleyL.tcl VictoriaL.tcl LomaPrieta1L.tcl LomaPrieta2L.tcl NorthridgeL.tcl ChiChiL.tcl ManjilL.tcl HectorMineL.tcl Iwate1L.tcl Iwate2L.tcl DarfieldL.tcl}
set TRecords {ImperialValleyT.tcl VictoriaT.tcl LomaPrieta1T.tcl LomaPrieta2T.tcl NorthridgeT.tcl ChiChiT.tcl ManjilT.tcl HectorMineT.tcl Iwate1T.tcl Iwate2T.tcl DarfieldT.tcl}
set TimeStep {0.005 0.01 0.005 0.005 0.01 0.005 0.02 0.01 0.01 0.01 0.005}
set Total {7890 2460 9995 7995 4000 18000 2675 4530 23800 12000 10725}

#defining earthquake record & assign
set iGMfile "[lindex $LRecords $i] [lindex $TRecords $i]" ; # ground-motion filenames, should be different files
set dt [lindex $TimeStep $i]
set TotalNumberOfSteps [lindex $Total $i]

#total time of ground motion + 10 sec of free vibration
set GMtime [expr $dt*$TotalNumberOfSteps + 10.0]

# timestep of analysis
set dt_analysis 0.002

#destroy all components of the Analysis object, i.e. any objects created with system, numberer, constraints, integrator, algorithm, and analysis commands
wipeAnalysis

constraints Transformation
numberer RCM
system UmfPack
test NormDispIncr 1.0e-7 50
algorithm NewtonLineSearch
integrator Newmark 0.5 0.25
analysis Transient

set IDloadTag 2; # for uniformSupport excitation

# Uniform EXCITATION: acceleration input
foreach GMdirection $iGMdirection GMfile $iGMfile GMfact $iGMfact {
incr IDloadTag;
set GMfatt [expr $g*$GMfact]; # data in input file is in g Unifts -- ACCELERATION TH
set AccelSeries "Series -dt $dt -filePath $GMfile -factor $GMfatt"; # time series information
pattern UniformExcitation $IDloadTag $GMdirection -accel $AccelSeries ; # create Unifform excitation
}

#number of steps in analysis
set NumSteps [expr round(($GMtime + 0.0)/$dt_analysis)]

#perform the dynamic analysis and display whether analysis was successful # ok = 0 if analysis was completed
set ok [analyze $NumSteps $dt_analysis]

if {$ok == 0} {
puts "Dynamic analysis of [lindex $Records $i] is completed"
} else {
puts "Dynamic analysis of [lindex $Records $i] did not converge"
}