Dear Ingrid,
I. it is not clear from your question if you have already seen ATENA Troubleshooting, 2.2.26 How can I model cyclic or fatigue loading? and 3.1.1 How to apply cyclic load?
I would also recommend 2.2.18 My analysis results do not match the experiment/expectations. How can I improve my model?
Ad 1.: Yes, the 40% from EC are quite high, see also for example http://forums.cervenka.cz/viewtopic.php?pid=527#p527
To set this (and see a figure explaining its meaning), please see the Tensile tab of the Material dialog for any material model from the NLCem family.
Ad 2.: Please see the corresponding help bubble in the material dialog (if you are using the ATENA-GiD user interface of ATENA Science). In short, disabled or 0 means unloading towards origin, and the limit when getting close to 1 corresponds to unloading parallel to the initial (elastic) response.
Ad 3.: If you do not have cyclic measurements for the particular material used for your reinforcement, you should find some publications for similar materials, and set the cyclic parameters to approximate the measured response under cyclic loading.
If you still have problems/questions, you can follow Troubleshooting, 2.1.1 to send us your model etc.
Regards.