Random Loads
We must design structures for random loads. In such circumstances
there can be no absolute guarantee of safety. The best we can do is to
create a structure with a known and acceptable probability of failure.
We define failure as any circumstance in which load>strength.
This would be true for any internal (load effect) as well as any external
load.
Both load and strength are random quantities (random variables).
The probability of failure is thus the probability that load exceeds
strength. We have a system of two random variables, and failure will
occur for every cases in which load>strength.
Typically we use open-tail probability density functions (eg Normal) so
that values theoretically go to ±∞.
The total probability of failure must cover all possible values of load and
strength. Failure can occur for any strength level, because it is always
possible that the load is even higher.
there can be no absolute guarantee of safety. The best we can do is to
create a structure with a known and acceptable probability of failure.
We define failure as any circumstance in which load>strength.
This would be true for any internal (load effect) as well as any external
load.
Both load and strength are random quantities (random variables).
The probability of failure is thus the probability that load exceeds
strength. We have a system of two random variables, and failure will
occur for every cases in which load>strength.
Typically we use open-tail probability density functions (eg Normal) so
that values theoretically go to ±∞.
The total probability of failure must cover all possible values of load and
strength. Failure can occur for any strength level, because it is always
possible that the load is even higher.
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