Module 17
Checking, review and design assurance
The only module whose subject is judgement rather than calculation: how to find out whether a design is right, and how to say honestly what it still does not know.
What this module covers
- Explain why repeating a calculation is not checking it
- Use an order-of-magnitude check to find the errors that actually matter
- Use equilibrium as an independent audit of the whole load path
- Judge what each level of checking can and cannot find
- Classify a finding by its consequence rather than its size
- Keep a register of what a design has taken on trust, and say what may be issued
Lessons
A second pass down the same road finds arithmetic slips and nothing else. What finds the errors that matter is a different road.
Start lesson →Every level of checking has a blind spot it cannot remove. And every design relies on things nobody has verified — which is only dangerous when it is not written down.
Start lesson →
Module checkpoint
Check what you have taken in
6 questions
Question 1
A concrete floor is estimated at 15 kN/m² factored, on beams at 5.0 m centres. Estimate the line load on a beam, in kN/m.
Question 2
A take-down says 3500 kN is applied and 3000 kN arrives at the foundations. What percentage of the applied load is unaccounted for?
Question 3
A beam has 3217 mm² of tension steel in a 350 × 650 section with d = 589 mm. What is the steel ratio As/(b d), as a percentage?
Question 4
A finding increases demand by 15% on a member whose utilisation was 0.50. What is the utilisation afterwards?
Question 5
A beam's self-weight is taken on its full 650 mm depth rather than its 450 mm downstand, on a 350 wide section. By how much is the line load overstated, in kN/m?
Question 6
How many of the 17 design values in this course's active standards profile are still NOT verified against their published source?