Mass definition

[shahinhus]

Hello. Please see below for the script. I would like to perform static analysis for a simple frame. I have added masses in the node and element definitions. But, they do not affect analysis results. When I define them as gravity loads, then they get applied to the frame. Why do you think they are not applied in the first place? Thank you.

wipe
model BasicBuilder -ndm 2 -ndf 3
set pi [expr 2.0 * asin(1.0)]
set g 9.81; # m/sec2

node 11 0.000 2.700 -mass 0.0 5.7 0.0
node 1 0.000 0.000

node 12 5.000 2.700 -mass 0.0 9.0 0.0
node 2 5.000 0.000

equalDOF 12 11 1

fix 1 1 1 1
fix 2 1 0 1

timeSeries Linear 1
pattern Plain 1 1 {
sp 2 2 -0.05
}

source materials.tcl
source sections.tcl

geomTransf Linear 1
geomTransf Linear 2

set Lpc [expr 2.7/4.0]
set Lpb [expr 5.0/4.0]

set WL [expr 1.53925*$g]

element forceBeamColumn 1 1 11 2 "HingeRadau 1 $Lpc 1 $Lpc 1"
element forceBeamColumn 2 2 12 2 "HingeRadau 2 $Lpc 2 $Lpc 2"
element forceBeamColumn 3 11 12 1 "HingeRadau 3 $Lpb 5 $Lpb 4" -mass $WL

system BandGeneral
numberer RCM
constraints Transformation
integrator LoadControl 0.02
test NormDispIncr 1.0e-6 100
algorithm Newton
analysis Static

recorder Element -file Forces.txt -ele 1 2 3 forces

analyze 50

print -ele 1 2 3

[mhscott]

Mass and weight (gravity load) are specified separately in OpenSees. One is not automatically calculated from the other.

https://portwooddigital.com/2020/11/20/mass-and-weight/

[shahinhus]

Thank you very much!