how to perform a simulation under different strain rate

[wcq19811982]

A dynamic analysis on concrete frame structure under different strain rate is performed, in the OpenSees program, how to achieve a loading method considering the influence of strain rate. For example, to simulate the dynamic responses under the strain rates of 0.0001, 0.001, 0.004 and 0.01 1/sec, respectively. It can be achieve by changing loading rate or modifying the material model?

[fmk]

there are few materials that are rate dependent in OpenSees other than those used for bearings and dampers. I doubt there are any concerete or steel materials that have rate dependecy built in. For those materials that are strain rate dependent, the rate comes from the change in disp. It is what it is, i.e. the rate that the materials see is coming from the change in displacement and the time step. changing the dt in a regular transient analysis is not going to change the rate, changing the loading history will.