The necessity to design composite building structures that are both safe and reliable has prompted the academic community to delve into the investigation of the bearing capacity of composite materials and forecast their mechanical behavior. Since most deformation of composite structures under impact is in the range of low to medium strain rate ( \(\dot{\varepsilon }\le 100\hspace{0.33em}{s}^{-1}\) ), this paper conducted experimental study and finite element analysis (FEA) on the nonlinear mechanical behavior of glass fiber reinforced plastic (GFRP) before damage under medium and low strain rates loading. A strain rate dependent elastic-viscoplastic constitutive equation considering the tension and compression strength-difference effect was proposed based on a nonlinear elastic–plastic constitutive model. The mechanical behaviors of GFRP laminate at medium and low strain rates were obtained by writing the explicit user-defined material subroutine (VUMAT). The prediction results of FEA are in good agreement with the experimental findings. Thus, the constitutive model can be used to predict the mechanical behaviors of the GFRP building structures at medium and low strain rates.
