Limit State For Steel Design
Section 2 of BS 5950 sets out the states for which steework is to be designed. Two common limit states used in civil engineering designs are the ultimate limit state and serviceability limit state.
To learn more about ultimate limit state and serviceability limit state, check my earlier post on limit states & principles of design.
Ultimate limit state takes account of the following:
1. Strength e.g. collapse, buckling, yielding, mechanism.
2. Stability against overturning and sway.
3. Fracture due to fatigue.
4. Brittle fracture.
Serviceability limit states include
1. Vibration e.g. wind-induced oscillation
2. Deflection
3. Repairable damage due to fatigue
4. Corrosion and durability
5. Cracking
The common practice in design is to design on the basis of strength and stability under ultimate limit state then, check deflection under serviceability limit state.
