In order to describe the mechanical behavior of highly anisotropic and asymmetric materials such as fiber reinforced composites, the elastic-plastic constitutive equations were used based on the recently developed yield criterion and hardening laws. As for the yield criterion, modified Drucker-Prager yield surface was used to represent the orthotropic and bi-modular (asymmetric) properties of composite materials, while the anisotropic evolution of back-stress was used to account for the hardening behavior. Experimental procedures to obtain the material parameters of the hardening laws and yield surface are presented for 3D braided glass fiber reinforced composites. For verification purposes, finite element simulation results based on the proposed constitutive laws have been compared with measurements for the three point bending tests.