For the derrick and its components with initial deformation, this method use Fourier series or simplify the equation to a half-wave sine curve for denoting the random initial deformation curve.

• 该方法是对于有任意初始变形的井架杆件或井架整体；可以用傅里叶级数来表示任意初始变形曲线；或简化成一个半波的正弦曲线；并结合实测变形数据；评定井架承载能力.