Radiation Fatigue?

What effect will radiation have on the structure of the habitat?

Consider that space vehicles degrade in performance as a function of
time the radiation they receive.

Will the habitat need to be maintained like a ship (40 years between
major overhauls or scrapping) or an airplane (also about 40 years
before metal fatigue necessitates structural replacement.)

What effect will the radiation in space have on the crystal bonds
within the metal or concrete of the shell?

Do you think that the shielding will degrade but that won't matter
because it won't serve a structural function and the shell of the
habitat will be protected by the shielding?

What does this say about designs that may want to incorporate the
mass of shielding into the structure of the habitat rather than have
it seperate?

Do you think that the habitat will have the maintenance problems of
ships and aircraft? I don't mean the sewer, electrical etc. I mean
the actual structure of the habitat. If so, then I fear it may be a
white elephant. Can you imagine having to repurchase the land your
house, business is on every 40-100 years? That's what a major
overhaul would amount to.