Here's my Q's it says on a lot of the sites you need to put a new box to support the weight of the new chandelier . My new chandelier will be mounted to a solid wood support beem that runs through the middle of my house so do I need a new box. 1 I don't even know if I could put a new box in anyway.2 I'm hoping the I won't need to it is already wired where I want to put it. Please help. Thank you

Mounting the fixture to wood with lag bolts so the box does not carry the weight is an approved method, just need to enclose the splices in an electrical junction box, of which there are many sizes and depths.

If this helps, there is a very shallow metal box, about 3/4" deep x 4" round, called a Pancake box.