cable tension and end loading

[David Wallace]

I am building a four post cable railing, approximately 20'x20' square. typical design loading is 250 pounds horizontal at any point..
Using a starting cable tension of 50 pounds, how would i determine an accurate corner post loading if the 250 is exerted on the cable? I've set up a test apparatus, but the numbers are not close to those predicted doing the vector arithmetic..

 

[Compositepro]

Well what does your vector arithmetic show? The trouble with cable railings is that cable tension can get very high at low deflections. You will likely need several support posts in 20 feet to keep deflection to an acceptable level.

 

[Compositepro]

You also posted this question in an inappropriate forum. Structural engineering would be more suitable.