Author(s)

DANDAN ZHENG, MASATO KOMURO, TOMOKI KAWARAI, NORIMITSU KISHI

Abstract

In this study, in order to establish a rational numerical analysis method for RC structures under falling-weight impact loading, a 3D elasto-plastic dynamic response analysis was conducted for flat-shaped RC beams. The beams have a rectangular cross section of 150 × 450 mm (height × width) and a clear span length of 2.0 m, which are an approximate one-fifth scale of the roof slab of existing RC rockfall protection galleries. Falling-weight impact tests were conducted by dropping a 300 kg steel weight onto the mid-span of the beam. Here, an influence of the element size of FE analysis on numerical simulation dynamic responses of the flat-shaped RC beams was investigated by dividing the intervals of stirrups (125mm) into 2, 5, 10 elements, in which these element sizes were 62.5 mm, 25 mm, 12.5 mm, respectively. An appropriate element size was determined comparing with the experimental results of the impact and reaction forces, the deflection at the loading point, and the crack patterns occurred on surfaces of the beam after the experiment. The results obtained from this study were as follows: 1) the time histories of the dynamic responses of the flat-shaped RC beams can be better simulated using a 25 mm of element size in span direction; and 2) maximum and residual deflections can be better predicted in spite of the magnitude of the falling height of the weight; 3) crack patterns of the RC beams can be better simulated applying the proposed numerical analysis method.

Keywords

flat-shaped RC beam, finite element analysis, element size, impact loading