Project Field E: Service Life and Safety

The proper assessment of the service life and of the safety of textile-strengthened constructions significantly decides on the application of textile-reinforced strengthenings. In the first two research periods, it has been proven that new safety concepts accounting for data and model uncertainty are required for textile-strengthened constructions. The uncertainty model fuzzy randomness has been enhanced to represent the basis for a new safety concept. As randomness (stochastics) and fuzziness are special cases of the generalized uncertainty model fuzzy randomness, all uncertainty characteristics that are present at textile-strengthened structures are taken into acccount. In contrast to the safety concepts on the code level, the developed new safety concept enables a much more comprehensive assessment of the safety. The safety concept has been coupled with the fuzzy stochastic structural analysis. On this basis uncertain limit states may be evaluated. The fuzzy stochastic structural analysis – as an enhancement of the deterministic structural analysis – also allows for a consideration of data uncertainty in the bond, in the roving strength, and in the finegrained concrete strength. The achieved state of development in project field E enables the assessment of the service life and of the safety under a broader variety of aspects in the third research period.

In subproject E3 the safety goal oriented design is developed. That is, the inverse problem to the safety assessment is to be solved. The envisaged solution strategy enables the determination of design parameters and also the derivation of statements regarding robustness and sensitivity of constructions with textile strengthening. Moreover, the theory for the numerical simulation of the time-dependent safety level is enhanced to additionally consider uncertain time-dependent changes of mechanical properties of textile reinforcement and of the bond.

subproject E4 has additionally been integrated into the project field. Its goal is the prognosis of changes at textile-strengthened constructions via numerical simulation. As long-term experiments cannot be performed within the time frame of the collaborative research center, the numerical simulation of long-term changes represents an alternative to obtain information regarding changes with impact on the service life on the basis of measurement series that are only moderate in length. Prognosis procedures are developed for real-time data – measured over a limited time period – and time-condensed data – measured under accelerating (time-condensing) environmental conditions.