| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve bending strength of a bending strength member while an increase in the weight is minimized. Ž<P>SOLUTION: A web 5 having a variable cross-section disposed between a pair of flanges 2, 3 parallel to the colliding direction indicated by an arrow is so shaped that the wall thickness on the inner side is larger than the wall thicknesses at both ends. The web 5 having a variable cross-section has a length L parallel to the colliding direction, a wall thicknesses t1 at the both ends, and a wall thickness t2 of a center part having a largest wall thickness with a distance of L/2 from the both ends. The cross-section of the web 5 is shaped symmetric, with a direction perpendicular to the colliding direction being right/left, and is so shaped that the wall thickness continuously increases toward the center part from the both ends so that the center part has a largest wall thickness. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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