The key word is "expected". This makes the persons that:
- estimates usage of this bridge over the expected life, and
- updates usage (number of lanes) and refurbishment as responsible as the original designer. Do they have the same qualifications? Do they get called into court? No. From their armchair, everyone blames the engineer.
And fatigued parts also.
Untrue. You may have an unusal (but not uncommon) definition of "well designed". Any material (except steel and carbon-epoxy composite) has a finite fatigue life, for finite applied load. So what has to be done, is to estimate the load, design the various joints to deliver that service, apply a factor of safety, and pray that the people that allow loads on it, and maintain it, and (apparently) inspect it all do their jobs.
When these things are not done, especially the loading *estimation*, fatigue-to-failure can be the result.
.=2E.
Lets hope so.
At least one person would not have died had this "lane reduction" happened. One of them only ever took this bridge based on traffic, and this would both have extended the life of the span (but not the mode of failure), and kept that person off this bridge.
Why? Because bearings suffer fatigue and corrosion.
I agree with you. I am just not naive enough to believe there is no fatigue allowed in real structures.
This has not been shown to be the case. This bridge is similar to thousands of others that have not failed, and do not have "structurally deficient" reports on them... presumably because someone maintained them.
Given that ASHTOO may cover this, and be stated on the design drawings, an additional statement may not be any more necessary than the number of lanes the bridge is to carry, the design loading, the tons of black top added, teh number of strikes by speeding snow plows, and the numbers of strikes by (ships and) ice navigating the Mississippi.
But there would be no chance for fatigue. Are you saying that what is known to work should be a basis for future designs now? Because what works, are designs exactly like this now-failed bridge, only with maintenance.
Untrue. Cite the relevant paragraphs that require this ad hoc addition of yours.
Untrue. If you don't build it only from cast iron embedded in bedrock, it will both corrode and suffer fatigue.
You say that like it is a dirty word.
A bridge is like building a car. The engineer and contractor build the car, but it is up to the owner to carry it through its 100 year mission. It is not like a firing a howitzer, where all the brainwork and muscle power occur at the time of launch.
I understand you will disagree with some of this. Your words can be the last.
David A. Smith