I'm getting a little late to the party here, so nobody may care about my response or my opinions.Rick, actually there are 3 discrete components, and therefore (in your example) 3 discrete stresses in the cables, and that's very important. Yes, the maximum stress is of course in the cable on the right hand side, and my calculations yielded 34.05K. The cable on the left hand side experiences 33.64K, and of course the vertical cable (or whatever the suspending element may be) suspending the 10K load is not carrying any horizontal load components, so is only under 10K of tensile stress.
And if you, as a building designer, are designing cable roof systems and they are being accepted by any jurisdiction
in the country, I would like to see the state law regulating the practice of engineering for the state in which you are doing work, and the code amendments for the jurisdiction that is accepting your design. Your statement about "usually" consulting an engineer when designing such systems frightens me to the core.
For anyone who cares, I think it is perfectly acceptable for any building professional to question the design assumptions, the calculations, the drawings, etc. for any submittal that comes through their jurisdiction, regardless of who designs or submits it. Doing so does not "make you liable for the design", or "responsible for the work"; that is B.S. Questioning any submittal is not only acceptable, but the responsible thing to do if you suspect something is not right.
Of course I also agree with those who say that if the building professional does not feel comfortable or qualified to challenge a design, they are certainly not obligated to do so.