Pre- and postyield finite element method simulation of bond of ribbed reinforcing bars

Both elastic and postyielding bond mechanisms between deformed bars and concrete are simulated by means of nonlinear three-dimensional asymmetric finite element analysis. Fine mesh discretization as well as fracture energy-based nonlinear constitutive models of the concrete is adopted in the computations. The degradation in bond due to yielding could be captured and explained by the finite element method results. The mechanics of bond in conventional concrete as well as self-compacting concrete could also be successfully predicted. The bond performance is greatly enhanced in the self-compacting concrete due to the nonexistence of the high porosity layers in the vicinity of bar. The bond behavior of normal strength concrete was found to be reasonably enhanced by adding a powder to the concrete mixture. This is attributed to the reduction of the pores in concrete. The bond behavior of aluminum bar was also successfully predicted confirming the effect of the bar strain on the local bond between concrete and deformed bars. The analysis could also predict the bond deterioration close to the crack or the free surface.