Modeling of Materials

The stress and strain characteristic of concrete used for the finite element analysis are shown in Figure 5. For the compression region, assuming that concrete is yielded at 1,500p strain, perfect elasto-plastic bilinear model was used. In this study, finally, yielding of concrete has been judged based on the Drucker-Prager’s yield criterion. For the tension region, linear model was applied, but it is assumed that the stress cannot be transferred when a tensile pressure acted in the element reaches the breaking point. Here, the pressure is evaluated as an average of three normal stresses acted in each element and the tensile strength of concrete is assumed to be 1/10th of compressive strength similarly to the case of the numerical analysis for small-scale RC beams conducted by authors. Stress-strain relationship for main rebar and stirrup was defined using a bilinear isotropic hardening model. Plastic hardening coefficient H’ was assumed to be 1% of Young’s modulus Es.

Yield of rebar and stirrup was calculated following von Mises yield criterion. Heavy weight, supporting gigues and anchor plates for axial rebars set at the both ends of RC girder were assumed to be elastic body because of no plastic deformation for those being found.