Time-varying Reliability Of Existing Prestressed Concrete Continuous Rigid Frame Bridge Bearing Capacity

In the course of Continuous rigid frame prestressed concrete bridge, not only towithstand the effects of vehicles, people, wind, snow, earthquakes and other externalforces, but also by the environment, the erosion of harmful chemicals, and materialsitself performance will continue to degenerate, such as concrete carbonation, crack, steelcorrosion, etc., along with time and traffics increasing, many continuous rigid framebridge suffered different degrees of diseases, embodied in web inclined cracks andlongitudinal cracks, and excessive midspan sag etc., which cause many continuous rigidframe bridge insufficient carrying capacity.Continuous rigid frame bridge after such problems arise, the security situation doesnot appear this kind of problem and how, and how to assess, and what kind of thecorresponding measures that we should take, which is we must solve the problem. Itrequires us to assess the in-service continuous rigid frame prestressed concrete bridge tocarry the reasonable assessment.Reliability of the bridge structure is relatively large on study both at home andabroad, and the relatively few studies on time-varying reliability of the bridge. In thispaper, the structural characteristics of continuous rigid frame prestressed concretebridge, at the conclusion on the basis of existing research, on the bearing capacity limitstate when the variant reliability issues in-depth research, the main tasks include thefollowing aspects:①The theoretical analysis of the structure of the basic the time-dependentreliability.Focuses on the basic principles of reliability theory, basic concepts, and introducesthe calculation method, calculating the component time-dependent reliability,calculating the system time-dependent reliability, and objectives reliability andevaluation criteria for reliability and so on.②ontinuous rigid frame bridge of common diseases and its main influencingfactorsThe main factors for continuous rigid frame bridge common diseases aresummarized, and works in conjunction with specific examples of the correspondinganalysis, then the impact of continuous rigid frame resistance were analyzed andsummarized. ③Aiable reliability calculation analysis of continuous rigid frame bridge beam flexuralcapacity.The first reference are summarized to the statistical parameters of load effect of thestandard, the resistance degradation problems, main influencing factors of concretestrength, against the force of prestressed tendons time-varying model are analyzed,especially for the corrosion of prestressing tendons after the remaining section area,mechanical properties, the effective prestress loss rate of bold innovation.④Variable reliability calculation analysis of continuous rigid frame bridge beamflexural capacity.First, the front binding norms and theory, time-varying resistance model, and thenrefer to the corresponding literature presented signs of structural failure and how to dealwith random variables in the process.⑤Continuous rigid frame bridge carrying capacity dependent reliability analysisexamples.Continuous rigid frame bridge Yunnan, for example, the use of software Midas/civil establish a finite element model, and according to the time dependent reliabilitytheory analysis of the various time-varying random variables using MATLAB uses asecond-order moment method (FORM method) and Monte Carlo methods (Monte Carlomethod) calculation principle, compile the time-varying reliability calculation program,and then calculate the continuous rigid frame prestressed concrete bridge carryingcapacity time dependent reliability, on this basis on the goal of reliability, predict theremaining life.