Question

The most economical section of a beam to bear maximum bending moment is

• A. square
• B. circular
• C. rectangular
• D. I-section

Answer 1

Answer:

D. I-section

The section modulus determines the maximum stress for a given bending moment. I-sections have the highest section modulus and are the most economical among cross-sectional geometries with equivalent cross-sectional areas. Rectangular sections have a lower section modulus than I-sections. Square cross-sections have a lower section modulus than rectangular cross-sections of the same area. Circular cross-sections have the lowest section modulus. Therefore, I-sections are the most economical section of a beam to bear maximum bending moment.