STRUCTURAL PERFORMANCES OF PRESTRESSED CONCRETE INTERIOR BEAM-COLUMN JOINTS

摘要

Four one-third scaled PC interior beam-column joints were tested by the authors. The main parameters of this test were the prestressing force and the bond condition between grouted mortar and prestressing tendons through a joint. The compressive strength of concrete and grouted mortar was 36 MPa and 40 MPa, respectively. The yield strength of prestressing tendon was 1100 MPa. Columns and beams of the specimens were reinforced by deformed bars with the yield strength of 500 MPa. Prestressing force was given from the ends of beams using post-tension method. These beam-column joints were analyzed using nonlinear finite element method (FEM). This analysis was carried out by considering the bond between grouted mortar and prestressing tendons similar to the tests. All specimens failed in the joint shear failure with both test and FEM analysis. The FEM analytical results gave a good agreement with the test results on the maximum story shear forces and the failure mode. From the comparisons between the experimental and FEM analytical results, the effects of the prestressing force and the bond condition between grouted mortar and prestressing tendons on the joint shear capacity were discussed. From the detailed investigations, the following conclusions can be made: (1) The joint shear cracking strength obtained from the tests was almost constant. However, the angles of shear cracking in the joint changed with the prestressing forces. (2) The shear capacity of the joint was not especially affected by the prestressing forces. (3) Because the bond between grouted mortar and rounded tendons was vanished on the earlier loading stage, the effect of the bond conditions on the joint shear capacity was not obtained obviously.