Limit state method

Limit State Method

                                The stresses are obtained from design loads and compared with design strength. In this method, it follows linear strain relationship but not linear stress relationship (one of the major difference between the two methods of design). The ultimate stresses of materials itself are used as allowable stresses. The material capabilities are not under estimated as much as they are in working stress method. Partial safety factors are used in limit state method.

                                    Limit state method design is called (LSD). LSD refers to a design method used in structural engineering. A limit state (LS) 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.