1.结构的位移 Displacements of structures
线位移：结构某点移动的距离（）Linear displacements or translation: the distance of movement of a point alone a line;
角位移（转角）：结构构件某截面转的角度（）Angular displacement or rotation:sectional rotation of a member of a structure.
相对（线）位移：两点之间距离变化
Relative linear displacement: the change of the distance between 2 points.
相对角位移（转角）：两截面之间夹角变化 Relative angular displacement:the change of the angle between 2 sections.
2.广义位移的概念 Generalized displacements
为便于进行理论分析和公式推导，将所讨论的各种结构位移用统一的符号来表示—，称为广义位移。For the convenience of the proceeding of theoretical analysis and derivation of formulae, we denote all kinds of displacements by , which is termed as generalized displacements
注Remark：广义位移可以看成为代表位移的抽象符号，在具体问题中表示具体位移. Generalized displacements may be looked at as abstract sign, which represents concrete displacement in concrete problems.