Force method for more than one unknown displacement
Force method for more than one unknown displacement
(OP)
I have a steel column that i'm designing for significant thermal expansion. It is pinned between two cantilevering concrete slab elevations. The column is located towards the outside edge of the cantilevered slabs. It's being provided to control vertical deflection of these slabs. I am trying to use compatibility equations to determine the accurate compression in the column when it's subjected to high temperature. I am able to successfully apply the force method when accounting for one slab's flexibility, and the other end as fixed, so only one degree of freedom. I am seeking insights as to how to apply force method when there are two unknown displacements.






RE: Force method for more than one unknown displacement
This problem could be solved with SAP2000. Perhaps your analysis program will allow you to apply the temperature change. You could do some easy problems to make sure it's doing what you want.
RE: Force method for more than one unknown displacement
http://www.engineering.uiowa.edu/~design1/Structur...
RE: Force method for more than one unknown displacement
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Force method for more than one unknown displacement
with one unknown, you remove the redundancy, calc the displacement; then determine the displacement for a unit redundant load; and so the redundant load = displacement/(unit load displacement).
with two unknowns, you remove both, calc displacements at both locations d1 and d2. now apply a unit load at 1, calc displacements at 1 and 2, u11 and u12. similarly unit load at 2, calc displacements at 1 and 2, u21 and u22. then ...
R1*u11+R2*u12 = d1 and
R1*u21+R2*u22 = d2
(assuming of cource that the unit directions oppose the d1 and d2 displacements).
clear as mud ?