Modeling of strain-electrical resistance relation of smart concrete

The performance of infrastructures is adversely affected by natural disasters, material degradations and other environmental factors. Structural health monitoring is an important issue regarding the safety of lives and asset management. The metal strain gages which are widely used in structural health monitoring are not durable, are costly and have low sensitivity. In this thesis, numerical models were developed for the piezoresistive behavior of smart concrete based on finite element method. Finite element models were designed using experimental data collected from compression test. The compression test was performed on smart concrete cube specimens with 75mm dimensions. Smart concrete was made of cement CEM II 42.5 R, silica fume, fine and coarse crushed limestone aggregates, brass fibers and plasticizer. During the compression test, electrical resistance change and compressive strain measurements were conducted simultaneously. Smart concrete had a strong linear relationship between strain and electrical resistance change. This relation is called piezoresistivity. These experimental observations were modeled by numerical methods. Twenty-noded solid brick elements SOLID226 were used to model the smart concrete specimens in the finite element platform of ANSYS Multiphysics 14.0. The numerical results were determined for strain induced resistivity change. The electrical resistivity of simulated smart concrete decreased with applied strain, as found in experimental investigation. The numerical findings are in good agreement with the experimental results. Modeling of smart concrete will enable the creation of a model that can be used by structural engineers.