Limit equilibrium method can calculate the normal use of the bending moment. In order to control the wall of the stress and deformation in the calculation of the minimum cross-section, the yield strength of steel to the introduction of 1.5 safety factor. Through these measures, you can ensure that the stress of sheet piling in general are in the elastic range.
Corrosion reduces the strength of the sheet piling wall, if the bending moment, the steel stress will increase. Obviously, the upper limit of corrosion is the yield stress of steel, which is the traditional method to define the effective life of sheet pile structure. In addition, the safety factor will decrease with time depending on the material failure.
If the temporary structure is not corroded by the limit equilibrium method, different yield strength can be used for the permanent structure and the temporary structure. Similarly, for temporary structures with short service lives, the yield strength of the steel is allowed to exceed its limit. The use of limit state design, the Z-shaped sheet piling
steel design stress is based on the yield strength of steel, and therefore can not arbitrarily change the design stress.