Experimental study and numerical modeling on bond between steel reinforcements and strain-hardening cementitious composites (SHCC)

Abstract

Strain-hardening cementitious composites (SHCC) are a type of pseudo-ductile material characterized by its tensile strain-hardening behavior, high tensile ductility and crack control capability. In many structural applications of SHCC, especially in repair work and joining of precast elements, good bonding with steel reinforcements is required to guarantee the stress transfer. Thus, the bond property between steel rebars and SHCC is an important issue to investigate. This paper presents the experimental testing and numerical modeling of the bond between deformed steel rebars and high strength SHCC. Bond test in direct tension is performed on specimens made of rebars and SHCC or concrete cover. The effects of materials, cover thicknesses and rebar sizes on the bond behavior are discussed. For the numerical simulation, instead of using a detailed model that involves complex geometry and comprehensive bond mechanisms, a simplified finite element model is adopted, which integrates all non-linear behaviors into spring elements linking SHCC and steel rebar elements. The spring behavior is back-fitted according to the experimentally determined load-displacement relation. To verify the effectiveness of the model, the modeling and experimental results for different specimen configurations are compared. The study reveals that the bond property between steel rebars and SHCC is superior to that between steel rebars and normal concrete, and that the cover thickness has a great influence on the bond strength. Further, the simple numerical model provides an effective method to extract the bond stress-slip behavior so that it can be used to determine the bond length for more general cases.