Atsuya TAKAMORI

ANALYTICAL STUDY ON THE STEEL MEMBER WITH CFRP ADHESIVELY-LAMINATED

Takeshi Miyashita

Due to the revision of road bridge specifications, it is expected to be applied to the limit state design method of CFRP adhesive steel members. From the above, it is necessary to establish a FEA model that can reproduce non-linear behavior of CFRP adhesive steel members. In the CFRP adhesive method, a material called a high-elongation elastic putty material (putty), which is like the rubber material is used as an adhesive resin to prevent detachment.
First, I examined the modeling method of resin materials. In general, when a resin material is modeled by a solid element, the dependence on the element size becomes high. Therefore, I proposed the method with the putty and the epoxy resin, are modeled by interface elements. In this model, it was found that the resin material has no element size dependence.
I investigate the Stress-Relative displacement relationship introduced into the putty material. First, in order to investigate the reproducibility of changes in the stress reduction effect, I modeled a uniaxial tensile test of the flat steel plate with CFRP. As a result, a triangular model with a stiffness　component obtained by dividing the elastic modulus by the coating thickness was obtained, in the normal direction. In the shear direction, a quadrilateral model with a 90% decrease in rigidity was obtained after the initial rigidity obtained by dividing the shear elastic modulus by the coating thickness. 
Next, to examine the reproducibility of sheet detachment and subsequent behavior, I modeled a uniaxial compression test of the flat steel plate with CFRP. As a result, in the normal direction, the maximum stress was set as the adhesion strength of the steel, and the softening behavior of a slope 1.3 times that of the rigidity component was obtained. In the shear direction, the maximum adhesion stress was 2.46 N/mm2, and the softening behavior was obtained as a cutoff with no slope.
From this study, I could propose an FEA model that has the reproducibility of the non-linear behavior such as the change in the stress reduction effect caused using putty material and the detachment.