A new point is put forward that transverse bimoment has different influence on the two kinds of cross section thin-walled beams, and on their St-Venant principle conditions. 2.

同时对外载等效经常现的横向双力矩这一广义力进行研，它在开口闭口壁梁约束扭转问圣维南原理适用条件分别占有不同的地位。