Analytical and numerical studies on impact force profile of RC beam under drop weight impact

Impact force and structural response of reinforced concrete (RC) beams under drop weight impact have been intensively studied and reported in the literature. The prediction of the peak impact force has been well investigated while the study of the overall impact force profile governing the structural response is limited. The impact force parameters acting on a structure including the peak impact force, plateau force, and impact duration all affect the structural responses. This study investigates the impact force profiles from drop weight impact on RC beams. The effects of global stiffness (by changing the beam span and boundary condition) on the impact force profile are numerically studied by using LS-DYNA. A two-degree-of-freedom (2DOF) analytical model is developed for RC beams under drop weight impact by using fiber beam section analysis method to predict the impact force. The developed 2DOF analytical model is validated by drop weight impact test results. With the validated analytical model, a simplified model of impact force profile is then proposed by determining six characteristic points, which are expressed by empirical equations fitted by the analytical parametric study results. The simplified impact force profile predicted by the empirical equations shows a good agreement with the test data.