Static analysis using "dispBeamColumn -mass" option

[sobeli]

Hello, I'm starting with OpenSees. I'm trying to perform an analysis of a simple 3D frame with fiber properties. I have used the "element dispBeamColumn" command with the "-mass" option to avoid placing the mass at the nodes. When I perform the dynamic analysis, OpenSees gives me good results, but I don't know how to perform a static analysis considering the masses already included in the modal analysis, to avoid place them again on the nodes or beams. Is this possible, or how would the analysis be done using "pattern plain"?



#
puts " DIMENSIONS...."
wipe
model BasicBuilder -ndm 3 -ndf 6
# Unidades
# Longitud - m
# Peso - Kg

set NumModos 1; # Se define el número de modos de vibrar a obtener.
set pi 3.1416;
set carpeta Resultados; # Se define el nombre de la carpeta donde se guardarán los resultados.

puts " NODES...."
# Joint X Z Y SacsJoint
# ----- -------- -------- -------- ------
node 1 0 0 0
node 2 3 0 0
node 3 3 0 3
node 4 0 0 3
node 5 0 3 0
node 6 3 3 0
node 7 3 3 3
node 8 0 3 3

puts " DOF...."
# Se definen los apoyos de la estructura.

fix 1 1 1 1 1 1 1
fix 2 1 1 1 1 1 1
fix 3 1 1 1 1 1 1
fix 4 1 1 1 1 1 1


puts " GEOTRANSF..."
geomTransf PDelta 1 -3.0 0.0 0.0
geomTransf PDelta 2 -3.0 0.0 0.0
geomTransf PDelta 3 -3.0 0.0 0.0
geomTransf PDelta 4 -3.0 0.0 0.0
geomTransf PDelta 5 0.0 3.0 0.0
geomTransf PDelta 6 3.0 0.0 0.0
geomTransf PDelta 7 0.0 -3.0 0.0
geomTransf PDelta 8 -3.0 0.0 0.0

geomTransf PDelta 9 0.0 0.0 3.0
geomTransf PDelta 11 3.0 0.0 3.0

puts " MATERIAL..."

#Modulo de elasticidad (Kg/m2)
#Esfuerzo a la fluencia (Kg/m2)
#Esfuerzo a la fluencia (Kg/m2)
#Densidad del material (Kg/m3)

set E 20389019158.00
set Fy 35153481.31

#7849.05 peso por unidad de vol Kg/m3
#800.38 masa por unidad de vol Kg/m4

set Dens [expr 800.38*0.005969026]
set Dens1 [expr 7849.05*0.005969026]

# Comando Material Tag Fy E b R0 cR1 cR2 a1 a2 a3 a4
uniaxialMaterial Steel02 1000 $Fy $E 1e-9 20 0.925 0.15 0.0001 0.0001 0.0001 0.0001


puts " SECTION TAGS..."
# Etiquetas de las secciones
set T1c1 2000


puts " ELEMENTS..."

section Fiber $T1c1 -GJ 423464.244 {
patch circ 1000 5 5 0.0 0.0 0.09 0.10 0.0 360.0
}
#

puts " ELEMENTS..."
#COLUMNS
# (etiqueta) (nodo i) (nodo j) (discretizaciones) (seccion tcorot) (peso vol por unidad de long)
element dispBeamColumn 3000 1 5 8 $T1c1 1 -mass $Dens -integration Lobatto
element dispBeamColumn 3001 2 6 8 $T1c1 2 -mass $Dens -integration Lobatto
element dispBeamColumn 3002 3 7 8 $T1c1 3 -mass $Dens -integration Lobatto
element dispBeamColumn 3003 4 8 8 $T1c1 4 -mass $Dens -integration Lobatto

element dispBeamColumn 3004 5 6 8 $T1c1 5 -mass $Dens -integration Lobatto
element dispBeamColumn 3005 6 7 8 $T1c1 6 -mass $Dens -integration Lobatto
element dispBeamColumn 3006 7 8 8 $T1c1 7 -mass $Dens -integration Lobatto
element dispBeamColumn 3007 8 5 8 $T1c1 8 -mass $Dens -integration Lobatto

element dispBeamColumn 3008 1 6 8 $T1c1 9 -mass $Dens -integration Lobatto
element dispBeamColumn 3010 6 8 8 $T1c1 11 -mass $Dens -integration Lobatto

puts "MODAL ANALYSIS...";

# Se define el amortiguamiento de la estructura.
set freq [expr ([eigen -fullGenLapack 1]**0.5)/(2.0*$pi)]
set dampRatio 0.05
rayleigh 0. 0. 0. [expr 2*$dampRatio/$freq]

puts "Periodo: [expr 1.0/$freq] segundos"

[serggg]

I'm assuming you want to do a response spectrum analysis? There is a responseSpectrum command if that's what you're looking for, I've never used it but you can look into the documentation if that's what you're looking for: https://opensees.github.io/OpenSeesDocu ... ctrum.html

[mhscott]

Mass and weight are separate inputs in OpenSees: https://portwooddigital.com/2020/11/20/mass-and-weight/

[sobeli]

Mass and weight are separate inputs in OpenSees: https://portwooddigital.com/2020/11/20/mass-and-weight/

Hey thanks for your advice, the web page that yor shared clears my daubt, thak you again