Module 03
Analysis of reinforced-concrete structures
Idealisation, effective spans, load patterns and moment redistribution — the decisions made before any section is designed, and the ones that quietly govern the answer.
What this module covers
- Measure a span correctly, and say why the choice matters
- Enumerate the load patterns that must be examined, and what each maximises
- Take a support moment at the face rather than the centreline, and justify it
- Explain moment redistribution as a trade of moment for rotation
- Apply the x/d restriction that redistribution imposes
- Judge when the simplified coefficients may and may not be used
Lessons
The decisions made before the analysis starts, which affect the answer more than the analysis does.
Start lesson →Moving moment away from a congested support — and the rotation you must pay for it.
Start lesson →
Module checkpoint
Check what you have taken in
6 questions
Question 1
A 300 mm deep beam frames into 500 mm columns with a clear span of 6.2 m. What is the effective span, in m?
Question 2
Why must the span moment be increased when a support moment is redistributed down?
Question 3
A support moment of 240 kNm is redistributed by 15%. What is the redistributed moment, in kNm?
Question 4
A 350 kN reaction acts on a 450 mm wide monolithic column. By how much may the centreline support moment be reduced, in kNm?
Question 5
The simplified moment coefficients for continuous beams may be used when:
Question 6
A beam is designed with x/d = 0.28 at a support. What is the maximum redistribution permitted, expressed as a percentage?