PROBLEM STATEMENT

Hints and Discussion Thread

Follow the four-step plan:

1. Equilibrium: FBDs and equilibrium equations for both member COK and  joint H. Assume all members in tension in your FBD. You should recognize that the problem is INDETERMINATE.
2. Force/elongation equations:  Write down the e = FL/EA + αΔTL equation for each of the three members (1), (2) and (3).
3. Compatibility equations: This step requires the most thought. Draw COK in a rotated position, either CCW or CW (your choice). For the sake of the discussion here, let’s assume CW.  A couple observations:
   • The downward vertical displacement of node K is v_K = e₂ + e₃. 
   • The horizontal displacement of node C to the left is u_C = -e₁. Use trig to relate  v_K and u_C to the angle of rotation of  bar COK.
4. Solve: At this point, you should have a sufficient number of equations to solve for the load in the three rod members.

Any questions? Ask (and answer) questions here.