To optimise the strategy for maintaining structures in the national road network, a software program that assists with the planning of interventions is necessary. The financial resources allocated for maintenance must be employed in an optimal manner in order to assure maximal use of the network. The results of the software program depend on the quality of the technical and economic models used. As of today the economic models have been well studied. The technical models, however, have not yet been treated in a satisfactory manner.
A synthesis of different studies on damage types, their mechanisms and their evolution, will be used to obtain degradation curves with respect to time and to determine the dominant parameters that describe the condition state of various structural elements. While studying the interaction between these elements, a model of the condition state of the complete structures will be developed. This model will be formulated so that it can be integrated into a software program.
The model developed will be tested by applying it to existing structures, conducting a sensitivity analysis of the parameters and comparing the actual condition state of the structures, based on reliable past data, with the condition state evolution predicted by the model.
The objective of this research is to create a complete model to predict the condition of concrete highway bridges based on solid technical considerations.
The developed model will be integrated into a software program that determines intervention times.
In this research, the condition development model is established, based physical and chemical phenomena involved in chloride induced corrosion.
Firstly, non-destructive testing methods are used in addition to visual observations, tu determine quantitative values of parameters governing the segment deterioration. It is proposed to divide structural elements into segments based on three concrete cover permeability classes, concrete cover thickness and three types of surface exposures to chloride contaminated water.
Secondly, two non-destructive testing methods are studied and applied - the measure of air permeability with the Torrent method and the measure of the rebar location.
Thirdly, a chloride transport model is developed to simulate a real exposure of reinforcement to chloride contaminated water, taking into account the transport mechanisms of water and chloride ions.
Fourthly, a relation is established between the free chloride ion content and the corrosion initiation probability.
Fifthly, the corrosion rate, i.e. loss of steel cross-section, is then determined according to the concrete cover permeability and the exposure to chloride contaminated water.
Finally, the results of the model are mapped to conditions states as defined in the BMSs.