极限状态设计法(LSD),也被称作荷载与抵抗力因子设计法(LRFD)，这是一种用于结构工程的设计方法。极限状态是当结构处于超过此状态时就不能够满足设计标准的一种状态。这种状态可以是某种荷载程度，或在作用于此结构的其它动作。设计标准是确保结构完整性、可使用性、耐久度和其它设计要求。用极限状态设计法设计的结构要能够承受其现实使用周期中可能发生的作用，并且能够保持可使用性，在各个极限状态下有着足够的可靠等级。基于极限状态设计法的建筑规范的规程中其实就已指明适当可靠等级的含义。

Limit state design (LSD), also known as load and resistance factor design (LRFD), refers to a design method used in structural engineering. A limit state is a condition of a structure beyond which it no longer fulfills the relevant design criteria. The condition may refer to a degree of loading or other actions on the structure, while the criteria refer to structural integrity, fitness for use, durability or other design requirements. A structure designed by LSD is proportioned to sustain all actions likely to occur during its design life, and to remain fit for use, with an appropriate level of reliability for each limit state. Building codes based on LSD implicitly define the appropriate levels of reliability by their prescriptions.