Abstract:

The dynamic performance of the interface connection between old and new concrete in prefabricated concrete members is studied based on the separated Hopkinson pressure bar test method. The test parameters include the average depth and number of grooves, the tilt angle of the interface between new and old concrete, the combination of three different concrete strength levels and whether reinforcement is installed. The results show that the impact pressure of the test and the inclined angle of the interface of the specimen have significant effects on the failure mode of the specimen, and the specimens can be divided into five categories according to the failure mode. With the increase of impact pressure, the strain rate of specimens with different interface inclination angles increases gradually. With the increase of strain rate, the peak stress of each specimen increases. The peak stress of the specimen with the interface inclination of 40°, the depth of grooves, the number of grooves and the strength grade of new concrete is higher. The interfacial shear stress of each specimen increases with the increase of strain rate. The shear stress is greater at the interface of specimens with an interface inclination of 40°. The reinforcement can increase the peak stress of the specimen under certain conditions. The interface bearing capacity formulas for calculating the unslotted specimens under static loading, the slotted specimens under static loading, and those under dynamic loading were derived in specimens without reinforcement. The results show good agreement with the experimental outcomes.

Key words: new and old concrete, interface, dynamic mechanical properties, split hopkinson pressure bar test