14.3.1.3. Probability of Failure

Try these first

1. 1.

   What does safety provisions refer to?

   Hint

   Think about protection factors in engineering designs.

2. 2.

   Name one factor that affects variability in resistance.

   Hint

   Consider where and how materials are sourced and applied.

3. 3.

   What is the primary goal of safety provisions in structural engineering?

   • To minimize costs
   • To limit probability of failure
   • To increase loads

   Hint

   Think about what ensures buildings are secure.

4. 4.

   True or False: A reliability index of 3.5 indicates a higher risk of failure.

   • True
   • False

   Hint

   Recall our discussion on reliability indices.

5. 5.

   Calculate the reliability index for a structural member given its load-carrying capacity and the expected load. If the load-carrying capacity is 9,000 lbs and expected loads vary but average at 8,500 lbs, can you assume it’s sufficient based on P = 1 - social concern?

   Hint

   Think about how normal distribution defines safety in margins.

6. 6.

   Discuss what changes would need to occur if a structure was found to have a low reliability index after completion. What steps should an engineer take?

   Hint

   Consider all alternatives engineers utilize to enhance structural integrity.