Skip to content
Queensferry

Module 06

Cross-section resistance

What a slice of steel can carry — in tension, compression, bending, shear and torsion, and in the combinations that actually occur.

What this module covers

  • Distinguish gross yielding from net-section fracture, and say why it matters
  • Calculate block tearing, and explain why it mixes a yield term with an ultimate term
  • Apply the section class to choose the right modulus
  • Derive the plastic shear resistance and say which part of it is code
  • Derive the N–M interaction of a rectangle, and see why an I section differs
  • Explain why an open section is so poor in torsion, and when warping takes over

Lessons

  1. 6.1

    Tension, compression, and the holes you drilled

    A tension member is the simplest thing in structural steel, right up to the point where you connect it.

    Start lesson →
  2. 6.2

    Bending, shear, and what happens when they combine

    One interaction in this subject falls out of mechanics. Every other one is fitted — and knowing which is which changes how much you trust them.

    Start lesson →

Module checkpoint

Check what you have taken in

6 questions

  1. Question 1

    A 6000 mm² tie in S355 has 5200 mm² net area. What is the gross yielding resistance, in kN? Take γM0 = 1.0.

  2. Question 2

    For that same tie, what is the net fracture resistance, in kN? Take fu = 510, γM2 = 1.25.

  3. Question 3

    A block has Ant = 750 mm² and Anv = 1800 mm², in S275 (fy = 275, fu = 430). What is the block tearing resistance, in kN?

  4. Question 4

    A rectangular section carries 60% of its squash load. What fraction of its plastic moment remains?

  5. Question 5

    A section has Wpl = 2000 × 10³ mm³ and Wel = 1750 × 10³ mm³. By what percentage does its bending resistance fall if it drops from Class 2 to Class 3?

  6. Question 6

    What is the shear yield stress of S460 steel, in N/mm², on the von Mises criterion?