According to the principle of the rigid body motioning , the theory composed the bending by the two principal axis and the rotation around the shear center to a rotation around a new point 此理论把构件绕两轴的弯曲平动和绕剪心的翘曲转动依刚体转动原理合成为绕新一点的转动,从而使杆件的空间稳定分析更加直观、简便。