Impact Material

[shenxian]

In my model ,i use the command :uniaxialMaterial ImpactMaterial $matTag $K1 $K2 $dy $gap
but i do not know the " $gap ",when the structure is skew, the gap is vertical distance or the other.
If anyone know this, i want you tell me in detail.
thank you very much !

[fmk]

it's going to depend on the element it is in ... i.e. truss or zerolength. and if a a truss, if regular or corotational. remember the material receives the strain from the element. what the strain is depends on the element type.

[shenxian]

hello,fmk.
first ,i must you.
now , i study the skewed bridge. i am modelling impact with a zero length element .

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

##### impact i node
node 93 4.3965 4.3965 0
- - - - -

fix 93 1 1 1 1 1 1

set matTag 1;
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°
########
but when i run the model i get force 0 , the displacement of the structure is enough to activate the element but i cant find why the element doesn't seems to work.
aometimes,the displacement is less than the gap,but the force is not zero. i don not know it is why .

how i should do, to achieve the skewed pounding.

[megiddo]

Maybe you can try this element:

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