Numerical Simulation of Interior Connections of Precast Concrete Frame with Post-Tensioned Tendons

In order to solve the problem that bond-slip of new and old concrete interfaces and treatment of shear reinforcement bars are challenges for finite element analysis of precast concrete frame joints, different methods in ABAQUS available for simulating the behavior of new and old concrete interfaces were deeply discussed. A new constitutive relation which combines bond-slip between new and old concrete interfaces with shear-slip model of shear reinforcement bar was introduced, and nonlinear finite element models (FEM) were carried out. The calculated results were agreed well with the experimental results of full-scale model test. And then an analysis of parameters was performed, which focused on influences of axial compression ratio, concrete strength, effective stress of prestressed tendon and bonded construction of prestressed tendons (full bond, partial bond and unbonded). The results show that bearing capacity increases by 11% with axial compression ratio increases from 0.2 to 0.4. However, the bearing capacity does not increase significantly when the axial pressure ratio increases from 0.4 to 0.6. Bearing capacity increases with the increasing of concrete strength and effective stress of prestressed tendons. Three types of bonding construction of the prestressed tendons have no obvious influence on the bearing capacity of the connections, but increasing the unbonded length of prestressed tendons may delay the connections yield.