For users looking for information on engineering issues...
It's unlikely that you'll get exact information on this, or any other forum, regarding structural and engineering questions. Not that we all don't want to help but more so because not many of us have an engineering background and unlikely that any of us are licensed engineers.
Even if a licensed engineer does come into the forum - I don't believe they will give much exact data either. The main reason is due to legal matters. If by some chance of fate - something happens that hurts, or worse yet kills someone, or causes property damage due to information provided by this, or any other forum, people think that the user could come back and open a lawsuit against the information provider.
We can only base our answers off from experience of what we've seen and not much more. We will answer your questions to the best of our knowledge but would suggest you to consult an engineer to get a true design that's safe for all parties involved.
Thank you for understanding.