I play T.T. very often as tanks, i.e. Rammus, Cho, Voil. Very commonly so long as someone on their team doesnt get too fed, I usually end carrying or runner up carry. I build pure tank with all of them and it usually goes they can't kill me and my damage output isnt amazing compared to AD carries, but I out survive them anyway, just too tanky.
Rammus: Merc Treads, Thornmail, Sunfire, Warmogs, Abyssal Scepter
Voil: Merc Treads, Warmogs, Sunfire, Banshees, Tri. force or Frozen Mallet
AP Cho: Merc Treads/Ninja Tabi, Rod of Ages, Abyssal Scepter, Frozen Heart, Deathcap, Sunfire/Banshees/ G.A.
Personally, Cho has most damage output (if you are constantly farming), but Voil carries the hardest, but Rammus pushes best and is best in team fights, and if played right, none just really die all that much