Solving for reactional forces in a Tower 1

[Gouthamm]

I have Tower Assembly, it has four columns and cross Bracings. As the columns of the Tower are fixed at the bottom, I was wondering if the assembly can be considered as a Statically indeterminate structure. If so, being a Mechanical Engineer I am clueless about how to solve for the reactions forces and moments at the bottom and resolving the force.
can someone please suggest how to solve this ?
Please find the attachment

http://files.engineering.com/getfil...-c232-46b2-8d37-c76c0979625e&file=Capture.PNG

 

[rb1957]

none so blind as those who will not see ...

(missed your very large Fh !?)

another day in paradise, or is paradise one day closer ?

 

[ukbridge]

I'd definitely go with Jayrod's solution; he also provides a very pertinent point that you/we may have missed ,namely that the "real" answer is really down to how the thing is going to be fitted/connected together. Some other things to think about:

1) Is the column a true "fixed" connection to the top "beam"? Or has it been designed as a simple connection permitting rotation?
2) Is everything going to node out, or will there be additional local moments exerted due to joint eccentricities?
3) How are you going to deal with the design of the connections (which can often be the critical case) if everything's welded together?
4) How many different load patterns are there going to be - if theres a lot it sounds like you're going to have to make a very complicated spreadsheet if you're implementing some kind of analysis which deals with statically indeterminate trusses like

http://www.sut.ac.th/engineering/Civil/CourseOnline/430331/pdf/09_Indeterminate.pdf

5) Will the provision of an extra brace outweigh the additional fabrication cost, for what may be a frame using modest standardised hot rolled sections.

If you absolutely insist on analysing it to the extent you want to, download a free frame analysis package like 2D frame and do it for a test-run. Ideally it should be a portable program so whoever else has to use it doesnt have to install the program also! Examine the output/datafile and with a bit of tooling you can use Excel and a few concenate functions to get excel to generate a handy script with little/no knowledge of programming.

I think the above idea is much better than programming your own spreadsheet; it will be less prone to errors and will be far more flexible than a spreadsheet could ever be for this type of thing. I don't think I've used a spreadsheet that doesn't have an error in it somewhere, and I don't think this project will be any different.

I think very often as structural engineers we're expected to produce perfectly working, validated spreadsheets; in reality we're not software engineers and don't have all day to make test cases and see if theres any errors in it somewhere.

 

[ukbridge]

...couldnt help myself, but as a final final option you could produce some simple graphs (and thus equations) using a 2D analysis package to help calculate the reactions in each member such as those in the Steel Designer's Manual, for a unit load. You could even vary the stiffness of the bracings as an addition parameter if you wish. This would also be beneficial I think for a graduate to learn the hard way that bracing isn't very efficient at certain angles! (Not that I think you're a graduate )