As a part of rock sheds, reinforced concrete (RC) girder is usually covered by traditional soil cushion as a shock-absorbing device. In this paper, expanded polystyrene (EPS) has been numerically modeled using RC girder under impact load analysis. A numerical method was established in comparison with the proposed prototype experiment. Furthermore, expanded polystyrene (EPS) cushions of different thicknesses and densities as an energy dissipation device for rockfall impact were tested using the proposed numerical model. The dynamic analysis and modeling were performed using LS-DYNA. The impact forces and displacements of the RC girder were measured. The simulated results revealed a major increase in terms of energy dissipation after introducing the EPS cushion. The results obtained from this study are: (1) the displacement can be reduced by 25% as compared to sand cushion as absorbing material using an EPS layer, (2) a large decrease in contact force was observed using a layer of EPS cushion at the top of the RC girder having lesser density of 19 kg/m3, and (3) EPS cushions with 0.5 m thicker layer and lower 19 kg/m3 density showed more remarkable energy dissipation effect when all the other conditions were the same.

Computational Modeling of Energy Dissipation Characteristics of Expanded Polystyrene (EPS) Cushion of Reinforce Concrete (RC) Bridge Girder Under Rockfall Impact

Expanded polystyrene (EPS) geofoam is an ideal material to construct seismic buffers to reduce earthquake-induced loads against rigid retaining wall structures. The paper provides a synthesis of published work by the writers on both experimental and numerical simulation work on EPS seismic buffers. Proof of concept is first demonstrated using a series of 1 m-high models placed on a shaking table. The tests showed that for the geofoam materials employed, a reduction in peak dynamic loads as great as 40% was possible compared to the rigid wall case. Next, a FLAC computer model was developed to simulate the experimental results. The validated model was then used to carry out a parametric analysis to investigate the influence of wall height, EPS geofoam type, thickness, stiffness, and excitation record on seismic buffer performance. One of the important outcomes of this research is that the practical quantity of interest to attenuate dynamic loads using a seismic buffer is the buffer stiffness defined as K = E/t (E = elastic modulus, t = thickness). For the range of parameters investigated in this study, K ≤ 50 MN/m 3 was observed to be the practical range for the design of these systems to attenuate earthquake loads.

S. Zarnani

Papers

EPS Seismic Buffers for Earthquake Load Attenuation against Rigid Retaining Walls