ROCKER PART STRUCTURE FOR VEHICLE

To reduce the weight of a rocker part without reducing collision safety performance and body rigidity even if the height of a closed cross-section of only a portion provided at a lower edge of a rear-side door opening of the rocker part is decreased.SOLUTION: The height of a closed cross-section of a portion 12 of a rocker part 1 disposed at a lower edge of a rear-side door opening is set lower than the height of a closed cross-section of the other portion 13 of the rocker part. In the intermediate of the rocker part, a gradual change section 14 in which the height of a closed cross-section gradually changes is provided. Inflection points 14a, 14b formed at both ends of the gradual change section are joined to a B pillar so as to be accommodated in forward and backward directions of the vehicle and in a B pillar 7 extended in a vertical direction of the vehicle. At a portion 12 lower in the height of a closed cross-section, a share panel 4 for restricting deformation of a lower portion of the rocker part is sandwiched by a joint between a rocker outer reinforcement 2 formed from a super high-tensile steel plate with a tensile strength of 1180 MPa and a rocker inner reinforcement 3 in forward and backward directions of the vehicle.SELECTED DRAWING: Figure 1 【課題】ロッカ部のリヤサイドドア開口部の下縁に設けられた部位だけの閉断面高さ位置を下げても、衝突安全性能及びボデー剛性を低下させることなく当該ロッカ部の重量を低下させる。【解決手段】リヤサイドドア開口部の下縁に配置されるロッカ部１の部位１２の閉断面高さ位置は、ロッカ部の他の部位１３の閉断面高さ位置より低く設けられ、且つロッカ部の中間位置にはその閉断面高さ位置が徐々に変化する徐変区間１４が設けられる。徐変区間の両端側に形成される変曲点１４ａ、１４ｂは、車両上下方向に延設されたＢピラー７の車両前後幅方向内に収まるようにＢピラーに接合されている。閉断面高さ位置が低い部位１２には、引張り強さが１１８０MPaの超高張力鋼板からなるロッカアウタリーンフォースメント２とロッカインナリーンフォースメント３との結合側間にロッカ部の低い部位の変形を抑制するシェアパネル４が車両前後方向に挟着される。【選択図】図１