Softening behavior

I am trying to model flexure of a material with softening stress-strain response. How can I model that! I know Abaqus can not handle negative tangent modulus. And, how do I simulate damage in the beam!

Any help/suggestion is highly appreciated!

hi my friends, i am new in Abaqus, while i am making a uniaxial compression test for coal  sample using Abaqus 6.6, the failure criteria is Mohr-coloumb plasticity, i know that the behavior of coal is strain softening. i should use this table to simulate the hardening/softening behavior of material.

 cohesion  yield stress

 Absloute plastic strain

i know that the first row will be the yield stress and the zero plastic strain.