We know stress and strength analysis of composite materials. Fiber glass and carbon fiber are light and strong materials that never rust and in many cases it is cheaper to build the structure with fiber glass materials than steels!
The design code DNVGL-ST-C501 was first issued in 2003. This is the code we mostly design against. For civil application, such as bridges and walkways we mostly use Eurocomp together with requirements from Eurocodes and Statens Vegvesen. For GRP pressure vessels we mostly use EN-13121, however, DNVGL-ST-C501 could also be used.
Fiber glass has anisotropic properties and in contrast with the metals has unequal mechanical properties in all direction. In the structures that is made of fiber glass materials, it is important that the fiber is used in the direction that is most useful for the strength. Therefore, there is possibility to reduce the weight of the structure significantly. In addition, it is possibility to have any shape or curvatures for structural parts.
For subsea protections it is very common to build the protection structures with GRP material.