- Title
- Spatial time-dependent reliability analysis of carbonation induced corrosion damage to RC structures under a changing climate and cost-benefit analysis of climate adaptation strategies
- Creator
- Peng, Lizhengli
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2015
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- The long term performance of infrastructure is an important consideration for asset owners, particularly in relation to reinforced concrete (RC) structures subject to corrosion. This thesis focuses on management of RC structures subject to carbonation induced corrosion under a changing climate. A changing climate may lead to increases in atmospheric CO₂concentration, and changes in temperature and relative humidity (RH), especially in the longer term, will accelerate the deterioration processes and consequently decline the safety, serviceability and durability of RC infrastructure. Therefore, modelling the deterioration process of RC structures under a changing climate and estimating cost effectiveness of climate adaption strategies can provide very useful information in decision making for the management of RC structures in corrosive environments. While there is much research on corrosion-induced deterioration of concrete structures, there is relatively little research on how deterioration can be affected by a changing climate. In this thesis, an improved carbonation induced corrosion model is developed by considering time-dependent atmospheric CO₂concentration, local temperature and RH effects. A new parameter ksite is introduced to take account local differences in CO₂concentration based on recorded data from various observation sites around the world. Future climates may be influenced by various factors which make projections difficult. Therefore, high and medium emission scenarios (i.e. RCP 8.5 and RCP 4.5), as well as a reference scenario, are used to cover the full range of possible outcomes. Many corrosion parameters and concrete properties governing the corrosion process are uncertain. Moreover, due to the spatial variability of workmanship, and environmental and other factors, it is recognised that the material and dimensional properties of concrete structures will not be homogeneous. So, it is necessary to model the spatial variability of the parameters in order to be able to characterise not only the probability of degradation, but also the extent of damage. This information is useful in optimising maintenance strategies. Random field is used in this thesis to model the spatial variability of corrosion damage. The method of discretisation and the random field parameters of element size, scale of fluctuation and correlation function are fully discussed in here. In addition, a cost-benefit analysis of climate adaptation strategies is developed based on spatial time-dependent reliability analysis described above. Climate adaptation strategies such as increasing concrete cover and upgrading concrete strength, as well as a maintenance strategy are defined. The cost-effectiveness of an adaptation strategy is measured in terms of Net Present Value (NPV). Both the mean NPV and the probability of NPV exceeds zero can be calculated to provide useful information for decision makers. RC beams and slabs for bridges and buildings in two Australian cities and three Chinese cities are investigated in the thesis. Durability design requirements, climate projections of specific locations and statistics of real structures’ parameters (such as concrete cover and concrete compressive strength) of RC structures in Australia and China are considered in order to make practical predictions. Cost data for adaptation and corrosion damages are based on local market prices of the two countries. Monte-Carlo simulation is used as the computational method to do the spatial time-dependent reliability analysis which includes the time-dependent climate scenarios and deterioration processes, as well as a large number of random variables and spatial random fields of material properties and dimensions. Sensitivity analysis is performed in this thesis to estimate the relative influences of the considered random variables. Break-even analysis is also conducted to provide a straight forward measure for decision makers to quickly determine if an adaptation strategy is cost effective or not. The overall results indicate that the reliability framework is well suited to predict carbonation induced corrosion damage of RC structures under a changing climate and assessing the cost-effectiveness of climate adaptation strategies. Moreover, the framework can easily adapt to updates or adjustments of information. The results and analysis can greatly assist designers and asset owner or operators in improving and optimising the management of RC structures in corrosive environments.
- Subject
- reinfoced concrete structures; climate change; reliability; carbonation induced corrosion; adaptation; cost-benefit analysis; spatial variability
- Identifier
- http://hdl.handle.net/1959.13/1296459
- Identifier
- uon:19266
- Rights
- Copyright 2015 Lizhengli Peng
- Language
- eng
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