Abstract
During the period of service, the infrastructure is subjected to various forms of impact. To investigate the impact responses of a reinforced concrete (RC) beam, a numerical model of the RC beam under impact was developed by the finite element package LS-DYNA in this study. The numerical model was verified by using the drop hammer test on the RC beam. Using the numerical model, the midspan displacement of the RC beam is analyzed under the interaction of impact mass and impact velocity. The results show that the response surface of midspan displacement can be fitted as a binary power function of impact mass and impact velocity. The midspan displacement under various impact conditions with equal impulse or equal impact energy is different. Within the scope of a low-speed impact, the midspan displacement decreases with an increase in the impact mass under the equal impulse, while it increases with an increase in the impact mass under the equal impact energy. In addition, the impact failure of the RC beam is judged by the deformation criterion. The threshold value of the ductility coefficient is recommended to be set as 15 in the impact-resistant design for RC beams in civil engineering structures within the scope of a low-speed impact.
Highlights
Ohnuma (1987) found that the peak impact force is considerably larger than the ultimate static bearing capacity of reinforced concrete (RC) beams
A 3D numerical model of the RC beam is developed by the finite element package LS-DYNA to simulate the drop hammer impact test
Impact force, and midspan displacement response obtained from the test and numerical simulation, it is found that the numerical model in this study can provide an accurate simulation of impact responses of the RC beam
Summary
Compared with the static load, an impact releases a large amount of energy in a short period time, which often results in serious damage to structures. Zeng and Xu (2012), Xu and Zeng (2014) carried out a drop hammer test on six RC beams to investigate the effects of different impact masses and initial impact velocities on the dynamic responses. Ohnuma (1987) found that the peak impact force is considerably larger than the ultimate static bearing capacity of RC beams From this result, we may deduce that the cross section would be unusually large if the impact force is taken as the design value. The displacement response of RC beams under impact, which provides a theoretical basis for the displacement-based structural impact design, is mainly analyzed under the interaction of impact mass and impact velocity. The numerical model is calibrated with the testing results of the drop hammer impact on the RC beam specimen. The failure of RC beam is judged according to the deformation criterion
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