Plastic Analysis MCQ with answer and solution

Concept

Plastic Hinge Formation

Formula

N/A

Step-by-step solution

1. Read the question asking for what is NOT a requirement for plastic hinge formation. 2. Recall that plastic hinges can form in both statically determinate and indeterminate structures, making determinacy non-essential. 3. Compare the given choices and select Option (d).

Explanation

A plastic hinge can form in both statically determinate and statically indeterminate structures. In fact, the main advantage of plastic theory is used in statically indeterminate structures, where multiple plastic hinges can form to redistribute bending moments before the entire structure collapses. Therefore, being statically determinate is not a requirement for a plastic hinge to form.

Shortcut

To remember the actual requirements for a Plastic Hinge to form in a steel structure, use the mnemonic "DPS": - Ductile: The material must be sufficiently ductile to undergo plastic deformation without premature fracture. - Plastic/Compact Section: The cross-section must be compact or plastic to prevent local buckling. - Stress Yielded: The entire cross-section must reach the yield stress.Memory Tip: Determinacy is NOT required—plastic hinges can form in both statically determinate and indeterminate structures.

Common mistake

A common mistake is misreading the question and missing the word "NOT", leading students to select actual requirements like option A, B, or C. Another frequent mistake is assuming plastic hinges only form in statically determinate structures, whereas in reality, plastic analysis is primarily applied to statically indeterminate structures where plastic hinges allow moment redistribution.