" knock " can denote an accidental action which hurts or breaks something . “knock”可指意外的动作，可造成伤痛或毁坏东西。
2.
Actions on structures - part 9 : accidental actions 对结构的作用.第9部分:意外作用
3.
" knock " can denote an accidental action which hurts or breaks something “ knock ”可指意外的动作，可造成伤痛或毁坏东西。
4.
Eurocode 1 : basis of design and actions on structures - part 2 - 7 : actions on structures ; accidental actions due to impact and explosions ; german version env 1991 - 2 - 7 : 1998 欧洲法规1 .支承结构设计和对结构作用原理.第2 - 7部分
