Reinforced Concrete Structure Reliability Research And Application Based On Life-Cycle Design

With the development of design theory of engineering structures, the research on life-cycle reliability theory of concrete frame structure arouses wide concern since the design codes have not taken into account the effect of degrading of structure on its performance in great detail. This paper focuses on the life-cycle aseismic reliability of the concrete frame structure, the major tasks and related research findings are summarized as follows:(1) Due to the different load values used for different service life, the seismic intensity, acceleration, maximum value of horizontal earthquake influence coefficient and return period during different service periods were derived based on the seismic probabilistic model. Then with 50-year seismic action as the benchmark, correction factor of maximum value of horizontal earthquake influence coefficient, correction factor of peak acceleration and correction factor of intensity were proposed. Calculating formulas of these correction coefficients were also derived. Parameters in the formulas were fitted using SPSS software in order to facilitate the application of the formulas, and error analyses were also carried out to verify the formulas.(2) The incremental dynamic analysis (IDA) method for calculating seismic reliability of the frame structure was introduced. This method adopt the inter story drift as the performance index. In addition, it gave the idea to compute structure life-cycle seismic reliability with a minimum resistance model.(3) The bar corrosion degradation model, the constitutive model of damaged concrete and the node slip model were analyzed. According to the analysis results, the calculation parameters of the frame structure during the whole life cycle were proposed. By comparing the structural reliability at different service periods, it was concluded that the longer service life of the structure was, the lower structural reliability would be. It also indicated that the deteriorating effect was more significant as the service life increased and earthquake became stronger.(4) The full life-cycle seismic reliability was calculated by using the minimum resistance method, and compared with the result of the structure with non-degraded material. The results showed that the failure probability of the structure with degraded material was greater than that with non-degraded material, and the gap widened with the growth of service life.(5) It is suggested that the existing structure which does not meet performance requirements should be reinforced. The relationship between structural maintenance costs and the reinforcement reliability was summarized, and the calculation method for structural failure costs was concluded. The maintenance and dismantling criterion were provided in this paper. The decision-making model of maintenance scheme was also prescribed. This model was verified by the reinforcement optimization of a frame example.