I would like to find out if Hasofer-Lind's Reliability Index is important for the estimation of reliability of structures.
I've made some good predictions using a meta-heuristic algorithm and one question that I have is if the usage of this index helps an engineer in some way or is just an easiest way to calculate the reliability rather than using the integral of the probability function.
Yes, it does. It has to do with the right programming of the algorithm. There are multiple ways of take into account many objectives.
But my question remains: does this calculation provides value to a decision maker? If I calculate a reliable design point very fast, does it mean that someone (e.g. political engineer) has a useful tool?
The mean value first order second moment (MVFOSM) reliability method needs to be improved for the following reasons:
Firstly, if g(.) is a nonlinear limit state function and the linearization takes place for the mean values of xi, errors will be introduced at increasing distances from the points at which linearization has taken place if higher order terms are disregarded.
Secondly, the results are not invariant with respect to the limit state function. That is, the value of the safety index depends on the limit state equation. For example if the nonlinear limit equation Μ=S2-Ζ2 is used, then pf=FM(0). If however the mean value and standard deviation are calculated and are substituted in
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The safety index is then
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This expression differs to that which corresponds to Μ=S-Ζ, despite the fact that the same failure criterion is used in both cases.
These problems can be superseded by use of the Hasofer-Lind procedure. In this, instead of selecting the linearization point on the basis of the coordinates of the mean values, linearization is performed at some suitable position on the failure surface. In this way the method becomes invariant with respect to the type of distributions used. On the failure surface the limit state function g(.) and its gradients are independent of the problem formulation.
Dear Prof Caridis,
I've send you a personal message about your answer. Please, take a look.
I'm looking forward for your response.
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