EXPERIMENTAL STUDY ON SEISMIC DAMAGE OF INTERIOR JOINTS IN INTEGRALLY PREFABRICATED REINFORCED CONCRETE FRAMES

In order to study seismic damage of interior joints in integrally prefabricated reinforced concrete frames, quasi-static tests were conclucted on one cast-in-place joint and three integrally prefabricated joints with different axial compression ratios. The damage process was observed and the mechanical properties of load-deformation and stiffness degradation were analyzed. Besides, the effects of axial compression ratios were compared. Finally, the modified Park-Ang’s damaged index model was used to discuss the influences such as axial compression ratios, concrete strength, stirrup eigenvalues and longitudinal reinforcement ratios on joint damage, and the total process damage of joints was quantitatively analyzed and classified. The results showed that the joints in the integrally prefabricated reinforced concrete frame under low cyclic loading went through five damaged stages in the test, in which the joints between beam ends and lower columns were the weak parts. The larger axial compression ratios could accelerate the joints damage. The increase of concrete strength, stirrup eigenvalues and longitudinal reinforcement ratios could obviously slow down the joint damage. The damaged index model used in the paper could better reflect the seismic damage of the tested joints.