difference between two kind of damper

[solmaz_moradpoor]

hi dear fmk
i have a question about modeling damper
you had proposed two kind of damper

[code]
element truss $eleTag $iNode $jNode $A $matTag

element zeroLength $eleTag $iNode $jNode -mat $matTag1 $matTag2 ... -dir $dir1 $dir2
[/code]

do performance these models in reducing response of structures to seismic loading are same?which one is better?
i tried both of them and their response was different.in first model(truss element), damper related to A and L(length of truss).

[fmk]

Well one is a truss and the other is a zeroLength element .. So yes A and L do effect the comparison of the 2 .. A=1.0 and L=1.0 should result in the same.

[solmaz_moradpoor]

hi dear fmk
i tested truss element with A=1m2 and L=1m but the results werenot same with zeroLength element.
performance these dampers in reducing response of structures to seismic loading arenot same.and reduction in model with truss element is more.
when i define stiffness for spring in damper, do A and L in truss element also participate in stiffness?

set K 288499;
set C 9375.4;
set alpha 1;
#
uniaxialMaterial Elastic 1 $K;
uniaxialMaterial Viscous 2 $C $alpha;
#
element truss $eleTag $iNode $jNode $A $matTag
element truss 1 12 122 1 1;
element truss 2 12 122 1 2;
very thanks for your attention