Kidrah:
Fair enough. But you still need to dig out your Statics, Strength of Materials, and first couple Structural Engineering text books if you are going to do this kind of work and want to look at all credible. You should also look for a local mentor, maybe your boss or a senior engineer who you can do sketches with and get an immediate critique from or redirection; see the same projects specs. and plans, and go over them at the same time for some preliminary ideas, etc. On this significant a design problem, your boss should know what you know and what you don’t know so he/she can guide you and keep you and the company out of trouble. He/she has a vested interest in seeing you do well and be successful. If you don’t have that kind of help within the company, look for it outside the company, but locally, so you can have a beer and just hash some of this stuff over, on a regular basis. Then come here for additional ideas, confirmation of your general approach, or a variety of opinions or refinements, etc.
And, still you didn’t answer half my questions, so I’ll try again. Is this the termination, dead man end, of the cables for your earlier suspension bridge? Are they cables or solid rods, they act quite differently? Your “Open questions” get you open ended, unending answers, and just tend to waste other people’s time guessing at what you want or are doing. A better problem definition in your OP, along with your sketch, would probably go a long way toward getting you better answers and ideas. Since the more complete you make your whole picture in the first place (your OP), the more closely the responses will hone in on your real problem; the more ideas, pros and cons, a better way, why this is dangerous or just won’t work, etc. These all come to mind, almost immediately, to an experienced engineer once he/she knows what you are trying to do. And, you may not even think of some of these for lack of the experience they have. The fact that you skipped right over the issue that Paddington and I picked up on, led me to more questions, specifically about your experience level. Since you say you ran this in RISA, please share with us what you got for the six spring loads, pipe deflections, along with some of the input stiffness’ and dimensions. I just picked my 14k, 12k & 7k out of the air, knowing nothing about the relative stiffness of the different elements in your system. Paddington’s guestimate was even more drastic than mine. I offered several ways to eliminate some of these problems, but you didn’t bite on those either. The transition structure from the suspension cables to the dead man or anchorage must be very stiff, so that deflection there doesn’t alter cable loadings. The cables should all elongate or be stressed at about the same level. Filling the pipe with conc. prevents pipe buckling and helps address the high bearing loads, and that’s good, and I suspect that was JAE’s first thought. Surrounding the pipe with conc. and proper reinforcing stl. (my dead man idea) would stiffen it and prevent it from deflecting, which was my intention. Or, you might eliminate the pipe bending issue and uneven spring loads by significantly reducing the length of the pipe or changing it to a much shorter solid 8" round bar. The longer pipe is probably not a good idea, and I have no idea what AISC table 4-17 says or looks like. You have to explain your reasoning better and then also listen for the potential drawbacks.
