DISCUSSION THREAD
This is an INDETERMINATE problem. Follow the procedure outlined in the lecture book for using Castigliano's method for determining the reactions on an indeterminate structure:
- Equilibrium: Draw an FBD of joint C. Write down the x- and y-components of the equilibrium equation for C. Determine the order of the determinancy (i.e., how many redundant loads are there?) Choose your redundant load(s), and write the non-redundant load(s) in terms of the redundant load(s).
- Internal resultants: Write down the force=elongation equations for the three elements.
- Strain energy: Write down the strain energy function U for the truss. Be sure that this function is written in terms of ONLY the redundant and applied loads. It should not contain any of the non-redundant loads.
- Castigliano's 2nd theorem: Apply Castigliano's 2nd theorem for indeterminate structures for each redundant load, R: ∂U/∂R = 0. Solve the Castigliano equation(s) along with the equilibrium equations above.
Please note that a detailed outline of the solution for this problem is found on the lecture video for July 10. You may want to review that before you start your solution.
Any questions? Ask (and answer) questions here.