Steuerung und Optimierung von Messprozessen durch die Berücksichtigung von Kostenfunktionen (Risk Minimization in Structural Safty Monitoring)
One main goal of structural safety monitoring is minimizing the risk of un-expected collapses of artificial objects and geologic hazards. Behind these activities in the DFG founded project, it is the need of the society in mini-mizing the negative environmental impacts. An optimal configuration for measurement setups and all other decisions shall therefore review and ra-te the risks of an individual monitoring project. Nowadays, the methodolo-gy in many engineering disciplines and mathematically founded decisions are usually based on probabilities and significance levels but not on the risk (consequences or costs) itself.
In the classical geodetic case, hy-pothesis testing in linear models is appliedto decide about a critical behavior of a structure. The two possible results of the test are the acceptance or the rejection of the predefined hypotheses, which are typically called null (stable struc-ture) and alternative hypothesis (instable structure), respectively. A typical example is to detect signifi-cant movements of a bridge. The choice of the null or alternative hy-pothesis is based on probabilities only, which have more or less no refe-rence to practical applications. E.g., when the same probabilities under acceptance or rejection region appear, wrong decisions can be made and each decision may lead to dramatically different consequences.
In this study, a new concept which is based on the utility theory is intro-duced to the current methodology. It allows the consideration of conse-quences or costs for decision making in order to meet the real require-ments. In this case, possible decisions are evaluated with cost functions for type I and II errors. Finally, the decision leading to the minimum costs or consequences is chosen as the most beneficial one. This procedure al-lows identifying the most beneficial additional measurements to reduce the risk of an individual structural monitoring process.
The theoretical concept is applied to an example in slope monitoring (see Figure). Based on the detailed information of point locations, the magnitu-des of possible damages can be determined. The risk of each individual point is then measured by the above mentioned strategy. Additional geo-detic measurements are carried out for the most endangered areas to re-duce the risk for the monitoring project.
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Zhang, Y.; Neumann, I. (2012): Risk Assessment for Slope Monitoring, Geodätische Woche. Hannover, 09.-11.10.2012.
Zhang, Y.; Neumann, I. (2013): Risk Assessment for Slope Monitoring, In: Journal of Applied Geodesy, Jg. 7, Nr. 3/2013, S. 159–171.
Zhang, Y.; Neumann, I. (2013): Minimising the Risk for Deformation Monitoring Projects, In: Proceedings of the 2nd Joint international Symposium on Deformation Monitoring. Nottingham, England.