Experimental Research on Impact Resistance of Partially Precast Concrete Beams

A building may be subjected to multiple accidental loads during its service-life. Partially precast concrete (PC) beam is a primary force-bearing member. When subjected to an impact load, its impact resistance will significantly affect the overall safety of the structure. In this study, five PC beams were designed and manufactured, and drop-hammer impact tests were performed. The influences of impact mass and impact height on the failure mode and the dynamic response of the component under different loading conditions were examined. The typical failure mode of the test beam under a dynamic load was derived from the failure mode and crack distribution. The dynamic responses such as impact force, supporting reaction force, and displacement-time-history curve were obtained by the test. With increasing impact energy, the peak impact force increased from 3,353 to 3,708 kN, the peak mid-span displacement increased from 33.6 to 47.3 mm, and the residual mid-span displacement increased from 11.9 to 15.1 mm. Subsequently, the law of energy dissipation in the impact process was analyzed using the combined curves of the impact force-mid-span displacement and support reaction force-mid-span displacement. Furthermore, the result obtained by the integration of the reaction force-displacement curve in the middle of the span is more suitable for evaluating the overall energy consumption of the beam. The vibration energy and internal energy of the beam itself account for the primary part of the remaining energy.