Problem with zero-length element and Hyperbolic element

[Amirsardar13]

Hi everyone,

I am having a problem in getting the hysteresis of a Hyperbolic element. I have defined the material like this:
set Kmax 83.15; # Initial stiffness of soil behind the backwall (Kip/in/ft)
set Fult 30.25; # Ultimate (maximum) passive resistance of soil behind the backwall (Kip/in/ft)
set gapAbut 1.0; # Gap between the superstructure and the backwall (in)

# Soil Abutment Interaction
# Hyperbolic Gap Material
# uniaxialMaterial HyperbolicGapMaterial $matTag $Kmax $Kur $Rf $Fult $gap
uniaxialMaterial HyperbolicGapMaterial $IDSoil [expr $Kmax/2.0*$s] [expr $Kmax/2.0*$s] 0.9 -[expr $Fult/2.0*$s] -$gapAbut

Because I am modeling a curved bridge, I have to define a longitudinal axis for zero length elements that I am using to represent the soil back bone springs. I am using these zero length elements at top and bottom of girders:

if {$n == 4} {

# At Abutment1 Location

uniaxialMaterial Elastic $IDbrgfree 0.001
set x 0;
set i 1;
foreach j {2 4 5 7} {
element zeroLength 1 2 3 -mat $IDSoil $IDbrgfree $IDbrgfree $IDbrgfree $IDbrgfree $IDbrgfree -dir 1 2 3 4 5 6 -orient [expr -sin($(teta$i))] [expr cos($(teta$i))] 0 [expr cos($(teta$i))] [expr sin($(teta$i))] 0
element zeroLength 2 4 5 -mat $IDSoil $IDbrgfree $IDbrgfree $IDbrgfree $IDbrgfree $IDbrgfree -dir 1 2 3 4 5 6 -orient [expr -sin($(teta$i))] [expr cos($(teta$i))] 0 [expr cos($(teta$i))] [expr sin($(teta$i))] 0
}

where all nodes are located at the top and bottom of girders and nodes 3 and 5 are completely fixed. teta$i is the angle at the considered abutment.
When I want to get the hysteretic behavior of the element, I am using these recorders:
recorder Element -file data/BrgFrc.out -time -ele 1 localForce
recorder Node -file data/BrgDisp1dir.out -time -node 2 -dof 1 disp;
recorder Node -file data/BrgDisp2dir.out -time -node 2 -dof 2 disp;

It seems it is not possible to use any other recorder such as "localDisplacement" to get the displacements. So, I have to get the nodes' displacements and then transform them into local axes. The hysteresis I achieve is not like what it should be (I mean Hyperbolic). I was also noticed that when I reverse the element's longitudinal oreintation, the results are completely different. Do you have any idea what I have to do to get the right hysteresis? Am I defining the material and element correctly?

[vesna]

I'm sorry I did not see this message before. Do you still have problems with zero-length elements and Hyperbolic material?

[Amirsardar13]

I solved it. Thank you. But I have a question about Remove recorder tag that I just posted on board. I would appreciate it if you reply to it asap.
Thank you.

[On3HitWond3r]

I'm having the same issues with this....how did you solve it?