Your question does have an answer but I don't know what the weight requirements are for your situation. Certainly, 3400lbs. is a lot of weight. If you find yourself stuck, perhaps a visit to Borders Book Store or a Home Center will have a book on porches and decks. Inside, I'm sure you'll find your answer. For the $20 (give or take) you spend for the book, at least you'd have spent very little $$$ for a great deal of peace of mind.
I don't expect you to get wrong info on this BBS but for what you're asking, you DO want a way to confirm the 'numbers'. My best to ya and hope this helps.