Ultimate load method

In this method, the structural element is proportioned to withstand the Ultimate Load which is obtained by enhancing the service load by some factor referred to as load factor for giving a desired margin of safety.

Merits:

1. The stress block parameters are defined by the actual stress-strain curve.
2. The calculated failure load matches with the experimental results.
3. It utilizes the reserve strength in plastic region.
4. It takes ultimate strain as the failure criteria
5. The load causing collapse is taken as the limit of safety.
6. The method allows selection of different load factors.

Demerits:

1. It totally neglects the serviceability criteria of deflection and cracking.
2. The uses of high strength deform bars affects in increase of deflection and crack width.
3. The effect on deflection due to creep and shrinkage is neglected.