FRP modelling in STAAD

[Meesamali512]

Hi Everyone,
Can anybody share how to model the FRP strengthening systems in STAAD.Pro v8i. I am planning on analyzing a tubular pile structure which has been strengthened using FRP wraps. I know all the material properties of the fiber wraps but can anybody guide me how to properly model them in STAAD. Also in case of fiber wrap systems, adhesives play a very major role as the whole strength depends on adhesive's capacity so how to take care of that during modelling?

 

[JoshPlumSE]

I don't think you can rely on your analysis to tell you when these members are failing. Rather you would use your analysis to determine what loading the various members experience. Then run some hand calcs (or get the FRP manufacturer to run them) to determine what the capacity of the members is.

 

[Meesamali512]

Actually my purpose here is NOT to determine whether members are failing or not, but I want to know how to effectively model the FRP system in STAAD so that it shows the actual behavior (or atleast near to it) after the structure is strengthened using FRP. Even if I give to manufacturer they will again come back and say that this FRP system can take so and so loads but HOW effectively it strengthens my structure. Would appreciate if you can refer something related to modelling part and I may also try the analysis using ANSYS too.

 

[JoshPlumSE]

On the analysis side, we're really just talking about how the FRP system affects the elastic stiffness of the members, right?

To me, that should be a simple calculation transformed section properties to come up with equivalent cross sectional properties for the multi-material members.

Acombined = A1 + nA2, where n = ratio between the young's modulus of the two materials. Same basic idea with moment of inertia....

 

[Meesamali512]

Thanks JoshPlum for your valuable input. I was actually planning on modelling the structure itself right way in STAAD. Hopefully it will go well. Actually for tubular members I think hoop stresses will also come into play and for modelling part I'm bit nervous about the Joints. Doing the proper wrapping of FRP plates around joints is really the tricky part.