A Performance Inspection Method Based On Probability For Precast Concrete Flexural Members

Currently the performance inspection method of precast concrete members is mainly derived from national standard TJ 321-1976?Standard of quality inspection and evaluating of construction and installation project: Reinforced concrete precast members?published in 1976 in China.In the past 40 years,approximate probability limit state design method has taken place of traditional empirical design method for concrete structure design.At the same time,building industrialization constantly propelled at domestic and overseas has greatly expanded the types of precast members,which resulted in the increase of risk for members social supplement.Therefore it is necessary to pay close attention to performance inspection for precast members,which is still experimental and not changed in essence.It means the current inspection method falls behind the development of the design method and the demand of building industrialization in the basic judgement method,judgement standard and application scope.Aiming at eliminating defects in the current inspection method,this dissertation developed a performance inspection method based on probability for precast concrete flexural members,which is based on the reliability control mode of the current design method and depends on structural reliability theory and statistics.The method maintains the uniformity with the current design method in reliability control,meets the demand of building industrialization in the application scope,and provides a more reliable technical support for building industrialization.The research contents and work include:1.Expressions of performance inspection method based on probability for concrete flexural members were proposed.After systematically reviewing the performance inspection method of concrete members in China and the statistical inference methods at home and abroad,the dissertation established a small sample inference method of design value for concrete members under the corresponding guarantee rate,which was obtained by reliability control mode of the current design method.On the basis of this,the paper proposed performance inspection method based on probability for concrete members.Based on the structural reliability theory and statistical basis,the probability method overcomes the defects of the current method.Furthermore,the same expressions form with the current inspection method is conducive for inspectors to accept and use the probability method.2.The probability characteristics of concrete flexural members performance were determined.According to the probability method,the probability characteristics of performance for concrete flexural members were evaluated in the dissertation,which solved the problems in establishing the probability characteristics analysis method of the bearing capacity under different failure modes,crack resistance,deflection and crack width.The work laid the foundation of the small sample inference method of design value and the performance inspection method based on probability for concrete flexural members.3.The risk control criterion of concrete flexural members performance were determined.The dissertation analyzed the guarantee rate of design value for concrete flexural members in current design code and calculated the lowest guarantee rate of bearing capacity,crack capacity,deflection and crack width.By calibrating and analyzing the confidence level implied in current inspection method,the dissertation put forward the recommended value of confidence level in performance inspection.In this way,the risk control criterion of concrete flexural members performance were determined,which is the key question in establishing the performance inspection method based on probability for concrete flexural members.4.The performance inspection method based on probability for concrete flexural members was proposed.On the basis of previous research work,the probability method was applied on performance inspection for precast concrete flexural members,including the bearing capacity,cracking capacity,deflection and crack width.The results of comparative analysis between the probability method and the current method revealed that the probability method for concrete flexural members could sufficiently and precisely assess the influence of probability characteristics and guarantee rate of members performance.Compared with the current inspection method,the probability method was developed on a steady theoretical foundation,maintained the uniformity with the current design method in the control of reliability,reflected the influence of probability characteristics and guarantee rate,and overcame the defects of the current method fundamentally.In addition,the inspection results were in accordance with the current method,which kept the risk control level verified by long-term engineering practice.