设有一任意截面,如图1所示。截面上外力N之作用面与X軸成θ角,此时可在重心上加二个大小相等,方向相反之N力。于是斜偏心外力N即可分为一个經过截面重心之軸向力N,及一个力矩M。如这截面之面积及抗矩为A及w,則截面上任一点P。(单位面积为a)之应力为: σ_p=N/A+M/W (1) 其中N/A均匀作用于截面上,不难計算,不作討 With an arbitrary section, as shown in Figure 1. The surface of the external force N on the cross section forms an angle θ with the X axis. At this time, two equal-sized and opposite-direction N forces can be added to the center of gravity. Then the obliquely biased external force N can be divided into an axial force N passing through the sectional center of gravity and a moment M. If the area and resistance moments of this section are A and w, then any point P on the section. The stress per unit area (a) is: σ_p=N/A+M/W (1) where N/A acts uniformly on the cross-section and is not difficult to calculate.