Statically determinate structure can be analysed by (i). Equilibrium equations (ii). Stress-strain consideration (iii). Compatibility considerations
- AOnly (i)Correct
- B(i) and (ii)
- C(ii) and (iii)
- D(i), (ii) and (iii)
Solution
Concept
A statically determinate structure is one where all unknown support reactions and internal forces can be found using equilibrium equations alone.
Formula
ΣFx = 0, ΣFy = 0, ΣM = 0
Step-by-step solution
1. In a statically determinate structure, the number of unknown reactions equals the number of available equilibrium equations. 2. Therefore, equilibrium equations alone are sufficient to find all internal forces and reactions. 3. Compatibility conditions and stress-strain relationships are only needed when analyzing statically indeterminate structures. Answer: (A) Only (i)
Explanation
A structure is statically determinate if equilibrium equations alone can find all reactions and internal forces. Stress-strain and compatibility conditions are required only for statically indeterminate structures.
Why the other options are wrong
B: Stress-strain considerations are not needed to find internal forces in determinate structures. C: Compatibility conditions are only required for indeterminate structures. D: All three conditions are required for statically indeterminate structures, not determinate ones.
Shortcut
Determinate = Equilibrium equations only. Indeterminate = Equilibrium + Compatibility + Stress-strain.
Common mistake
Students often confuse determinate with indeterminate structures and select all three options.
Correct answer: A) Only (i)