Abstract:

A finite element model of the three-span scaled-down W-beam guardrail system under impact loading is established in this paper.The dynamic response of the guardrail system under the impact loading is analyzed by using the LS-DYNA finite element code,and the instantaneous deformation process of each part is revealed,inclu.ding the bending of the W-beam,the extruding of the blocks,the torsion and bending of the posts.Then,the varia-tions of the acceleration and the velocity are investigated,showing that the impact acceleration of the loading head rapidly increases at the beginning and then gradually decreases to zero,while at the same time,the impact velocity gradually decreases to a reverse value.Moreover,the energy-absorbing characteristics of the guardrail system in the impact process are analyzed.It is found that the impact energy of the loading head mainly translates into the inter-nal energy at each part of the guardrail system and the residual kinetic energy at the loading head,and that the blocks and the W -beams are the main parts absorbing energy .The analytical results are finally compared with the experimental ones and they are found to be consistent,thus revealing the validity of the proposed model.

Key words: three-span guardrail system, impact, dynamic response, finite element method