Analysis And Research On Maintenance Strategy Of Reinforced Concrete Bridge Based On Life-cycle Design Theory

Under the traditional bridge design concept,people often only pay attention to the initial construction cost of the bridge and ignore the later maintenance.In the subsequent practice,it was found that a large number of bridges suffered serious damage during the late service.Even,the maintenance cost of some bridges exceeds their initial cost,resulting in a large amount of waste of funds.So on the basis of summing up experience,some scholars put forward the concept of life cycle design based on life cycle cost.This new design concept considers not only the initial construction cost but also the future maintenance cost at the beginning of bridge design.Because maintenance cost plays an important role in life cycle cost,it is necessary to study bridge maintenance scheme and its corresponding maintenance cost,which has a positive guiding significance for bridge management.On the basis of previous studies,this paper develops and enriches the high-order non-linear deterioration model of bridge structure,and derives the maintenance model of structure under different maintenance conditions.The feasibility of the deterioration model is verified by comparing with the theoretical calculation results.The main research work and conclusions of this paper include the following points:1.From the point of view of dynamic reliability,the performance of bridge structure is analyzed,and the variation rules of reliability indices of original design and life-cycle design under general and intensive operation conditions are calculated with engineering examples.The results show that the initial reliability index of the structure is larger than that of the original design,and the time to deteriorate to the target reliability index is longer than that of the original design.It shows that under the concept of life-cycle design,the performance of the structure has been improved,and the deterioration is slower,which is conducive to the later maintenance of the structure.2.This paper develops and enriches the dual-nonlinear deterioration model of structural reliability index and conditional state index,in which the research of reliability index deterioration model is the main one.Monte Carlo simulation method is used to simulate and analyze the deterioration model proposed.Compared with the theoretical calculation results,the analysis conclusion shows that the deterioration trend of the model is consistent with the theoretical calculation trend.According to different maintenance strategies and combined with the deterioration model in this paper,the calculation formulas of structural reliability index and state index at any time under each maintenance strategy are deduced,and the corresponding maintenance model is obtained.3.The simulation results of the non-linear degradation model in this paper are compared with the linear degradation model and the exponential degradation model.It shows that the high-order non-linear degradation model is more in line with the degradation in the actual work of bridges than the linear degradation model.The simulation results of the exponential deterioration model delay the time of reaching the target reliability index more than the theoretical calculation results,and then the simulation results delay the deterioration of the actual work of the structure,which is not conducive to the safety of the structure.The results of the high order nonlinear deterioration model in this paper reach the target reliability index earlier than the theoretical results,which shows that the model in this paper is more suitable for describing the deterioration law of structures than the linear deterioration model and the exponential deterioration model.4.Combined with actual maintenance activities,the effects of single maintenance activities and combined maintenance activities on structural reliability index and corresponding maintenance costs are studied.The results show that neither complete maintenance based on performance control nor preventive maintenance can meet the dual-objective requirements of structural reliability,performance safety and maintenance cost reduction.After adopting the combined maintenance scheme,the research results show that the dual-objective requirements of performance and cost have been achieved.