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1、第二部分英文翻译Reliability analysis :a structures management tool for concrete bridgesReinforced concrete structures are susceptible to a variety of deterioration mechanisms, including alkali-thaw action and chloride ingress. Substantial research has been undertaken in relation to these mechanisms and othe
2、r problems. This has particularly been the case over the last 20 years or so, where the objective has been to identify causes, consequences and develop remediation strategies. This has improved understanding of long-term behaviour of reinforced concrete and resulted in the development of techniques
3、to increase deterioration resistance.At present, the most common approach is to act after a problem has been identified, known as re-active maintenance. This may not be the most economic solution since, in many cases, maintenance is more costly than preventative treatments. However, owners are often
4、 reluctant to pay for preventative treatments before deterioration is apparent. Early application of treatments may not be the optimal solution in the long run. Integrated deterioration and performance prediction modeling is essential to pro-actively plan and prioritise inspection, testing and maint
5、enance. This becomes increasingly important as infrastructure ages and /* 彳、 彳、 *!*! *! justification for maintenance funding becomes increasingly critical.Performance assessment can be achieved through surveys, testing and formal calculations, ideally based on site data that represent, as accuratel
6、y as possible, the state of the structure. By integrating predictive deterioration models with assessment tools and performance criteria (at element, structure or group level) it becomes possible to base the maintenance regime on time-dependent performance profiles. This is particularly relevant in
7、the context of whole-wife costing procedures.Substantial research has been undertaken in relation to these mechanisms and other problems. This has particularly been the case overthe last 20 years or so, where the objective has been to identify causes, consequences and develop remediation strategies.
8、 This has improved understanding of long-term behaviour of reinforced concrete and resulted in the development of techniques to increase deterioration resistance.At present, the most common approach is to act after a problem has been identified, known as re-active maintenance. This may not be the mo
9、st economic solution since, in many cases, maintenance is more costly than preventative treatments. However, owners are often reluctant to pay for preventative treatments before deterioration is apparent. Early application of treatments may not be the optimal solution in the long run. Integrated det
10、erioration and performance prediction modeling is essential to pro-actively plan and prioritise inspection, testing and maintenance. This becomes increasingly important as infrastructure ages and /* 彳、 彳、 *!*! *!justification for maintenance funding becomes increasingly critical.Reliability analysis
11、 has emerged as an important tool in this multi-objective management process, which must take into account safety, functionality and sustainability criteria. In simple terms, the reliability of a structure or a system is the probability of achieving a particular performance level. Probability or lik
12、elihood is the appropriate measure, since all engineering systems are susceptible to uncertainties, arising from random phenomena and incomplete knowledge. Reliability analysis in structural engineering enables quantification of uncertainties associated with loading, materials, deterioration, modeli
13、ng and other factors. These are integrated into a method that estimates the probability of reaching the specified performance level during the service life of a structure. The method is increasingly being used in bridge engineering, both for calibration of safety levels in codes and standards and im
14、proving and refining assessment methodologies. The purpose of this article is to outline its application in managing bridges susceptible to deterioration.Although data for many deterioration variables can be derived from laboratory studies, there is an absence of similar data real structures. An imp
15、ortant feature of the model is the facility to modify initial predictions, based on published (known as prior) data, using information and data obtained directly from the actual structures. Reliability analysis is appropriate for this pursose as if it can readily incorporate additional data, updatin
16、g the probability of reaching a performance target. The concept is analogous to updating the probability of arriving on time whilst on a train, having just obtain some extra information regarding the operating conditions ahead.Typical results produced by the probabilistic deterioration model for a crossbeam chloride exposure zone, similar to the delaminated area shown in Figure 3,are shown in Figure 4.Assuming a threshold of 40% initiation
