How to support an overgrown Duranta Tree
I have had my Duranta Tree since it was about a foot tall. It was planted in the front porch of my house and I have been shaping it into an "umbrella style" to provide shade for our seating area on the porch; pruning annually. A specific branch has been the ample support to the smaller branches growing around the tree helping with "umbrella look." Unfortunately we had some heavy rain here in Socal last night and I awoke to the main branch having broken off, therefore causing most of the tree damage. I am very saddened by this and am hoping to prevent this from happening again. So, my question is, how can I support the branches and tree from drooping over and becoming so heavy causing the branches to snap due to the weight of rainfall, whilst achieving the "umbrella look?" Any suggestions are greatly appreciated. With that being said, the tree is in my front yard so I am limited as to what materials and how big this support system can be. Thank you very much.
Without a photo or description of the size and spread of the tree, it's hard to visualize and give specific recommendations.
In general, it's best to achieve the umbrella form with selective pruning and with thinning and branch end-weight management to avoid over burdening and breakage.
An artificial support system may be hard to achieve with your situation. Since cabling within the tree branch structure doesn't seem practical. The next option would normally be vertical supports/props from a base at soil grade to the under side of a scaffold branch. But in your plant's case and location, that also may not be attractive or practical. A system of angled rigid props from the tree trunk out to selected horizontal branches may be possible to design, but I know of no established practice or material for doing this, and even though I have engineered an installed many tree support systems, I cannot visualize what those attachment points would have to be like.
So my best guess, without the advantage of seeing the tree, would be that you are limited to directional and weight reduction pruning.