impact model have problem.

[shenxian]

hi，
I am study skewed bridge, in my model, am modelling impact with a zero length element. and the impact element is skewed. when the displacement of the girder is greater than the gap. But the zeroLength element do not have force.

### girder 1:node
node 1 4.3965 4.3965 0
node 2 4.7465 4.3965 0
node 3 5.0965 4.3965 0
----

### girder 2 :node
node 22 1.45 1.45 0
node 23 1.80 1.45 0
node 24 2.15 1.45 0
- - - -

### girder 3:node
node 43 -1.45 -1.45 0
node 44 -1.10 -1.45 0
node 45 -0.75 -1.45 0
- - -

### girder 4:node
node 64 -4.3965 -4.3965 0
node 65 -4.0465 -4.3965 0
node 66 -3.6965 -4.3965 0
- - -

##### left impact i node
node 93 4.3965 4.3965 0
node 94 1.45 1.45 0
node 95 -1.45 -1.45 0
node 96 -4.3965 -4.3965 0

puts "restraint"
##left impact i node
fix 93 1 1 1 1 1 1
fix 94 1 1 1 1 1 1
fix 95 1 1 1 1 1 1
fix 96 1 1 1 1 1 1

puts "impact element"
set matTag 11;
set K1 2.1294143e9; # initial stiffness
set K2 2.4435902e8; # secondary stiffness
set dy -0.00254; # yield displacement
set gap -0.05; #gap
uniaxialMaterial ImpactMaterial $matTag $K1 $K2 $dy $gap;

element zeroLength 221 93 1 -mat $matTag -dir 1 -orient 0.7071 -0.7071 0 0 0 1; ## x:45°、135°、90°; y:90°、90°、0°
element zeroLength 222 94 22 -mat $matTag -dir 1 -orient 0.7071 -0.7071 0 0 0 1;
element zeroLength 223 95 43 -mat $matTag -dir 1 -orient 0.7071 -0.7071 0 0 0 1
element zeroLength 224 96 64 -mat $matTag -dir 1 -orient 0.7071 -0.7071 0 0 0 1

Whether or not, i need to tie together nodes of zeroLenght elements in other two directions. But in my model , the zeroLenght elements is skewed.
What should I do?

[megiddo]

You can try this element:

http://opensees.berkeley.edu/wiki/index ... thImpact3D