The documentation on the effect of the damage flag seems unclear. I changed the flag from blank to 0 to -1 +1 etc, and it does not seem to affect the behavior. I want the material to remember the maximum past gap, but it always seems to remember to the original gap during cyclic loading.
The documentation for this material is appended below
#uniaxialMaterial ElasticPPGap $matTag $E $Fy $gap <$eta> <damage>
#$matTag unique material object integer tag
#$E tangent stiffness
#$Fy stress or force at which material reaches plastic state
#$gap initial gap (strain or deformation)
#$eta hardening ratio (=Eh/E), which can be negative
#damage a switch to accumulate damage in the material. If damage is omitted, default value, the gap material "re-centers" on load reversal.
here is a link to the current documentation:
http://opensees.berkeley.edu/wiki/index ... p_Material
I am working on gap material right now and I could not find any example of using the command. Can anyone share a gap material example? I would appreciate it.