Rearch On Probabilistic Method Of Construction Monitoirng And Control Of Prestressed Concrete Cable-stayed Bridges

Prestressed concrete cable-stayed bridge is a type of large-span bridge used widely. Withcomplicated construction technology, numerous influencing factors and various methods ofconstruction adjustment, the construction monitoring of this type of bridge is complexrelatively and also most significant. The traditional theoretical system of constructionmonitoring of large-span prestressed concrete cable-stayed bridge has been widely applied inengineering practices. But for the influence mechanisms of uncertainty of various influencingfactors in construction monitoring, the present theoretical system cannot provide a scientificand rational explanation in terms of probabilistic reliability. It results in lacks of recognition onthe variability of structural responses in practical construction and the measuring accuracies ofdifferent measuring items, which leads that the reliability of parameter identification as well asthe efficiency of measures taken in construction adjustment cannot grasped exactly.Therefore, it is urgently needed to establish a theoretical system based on probabilisticreliability theory for uncertainty analysis of construction monitoring. Stochastic analysis andreliability theory will be applied throughout every link of construction monitoring, whichmakes the links of construction monitoring linked each other and being an organic whole, andSo as to establish scientific and reasonable accuracies of construction control in engineeringpractices of construction monitoring, judge and measure the measuring accuracies of variousmeasuring items as well as the identification precisions of main design parameters. Eventually,the goal of the construction errors adjusted safely and effectively can be achieved, then thecomplex and heavy work of construction monitoring can be conducted with high quality andefficiency.In this dissertation, on the basis of the present traditional theoretical system ofconstruction monitoring of prestressed concrete cable-stayed bridge, and combined withprobability theory and mathematical statistics theory, the study on the probability analysismethods for each links of construction monitoring is developed. The following research resultsare achieved in this dissertation:(1) Current theoretical systems of construction monitoring of prestressed concretecable-stayed bridge are reviewed comprehensively. The uncertainty factors existing in the construction of prestressed concrete cable-stayed bridge, as well as structural stochasticanalysis methods and the related concepts of structural reliability are presented. The difficultiesfaced in the construction monitoring of prestressed concrete cable-stayed bridge withinfluences of uncertainty factor, as well as the current status of probability analysis for theconstruction monitoring of prestressed concrete cable-stayed bridge are summarized.(2) Measurement methods for internal forces and concrete stress are presented. On thebasis of the methods, and combined with probability theory and mathematical statistics theory,the probability analysis method for the internal force measurement of prestressed concretecable-stayed bridge is proposed, so as to provide an effective method for determining thestatistical characteristics of measured internal forces and obtaining the probabilities of internalforce measurement within different measuring accuracies. With the probability analysis of theinternal forces of Ganzhuxi Bridge, the type of probability distribution and statisticalcharacteristics of the measured internal forces of Ganzhuxi Bridge are determined, and theprobability information with different measuring accuracies are acquired too. That proves thatthe probability analysis method for internal force measurement is feasible.(3) The contents and objective of construction control, as well as the simulation method ofconstruction, are discussed. On the basis of that, and combined with probability theory andmathematical statistics theory, the probability analysis method for construction control ofprestressed concrete cable-stayed bridge is proposed, so as to provide an effective method fordetermining the statistical characteristics of structural responses in the process of constructionand obtaining the probability of the construction control within different control accuracies ofconstruction. With the probability analysis of the internal forces of Ganzhuxi Bridge, the typeof probability distribution and statistical characteristics of structural responses in the idealconstruction process of Ganzhuxi Bridge are determined, and the probability information withdifferent accuracies of construction control are acquired too. That proves that the probabilityanalysis method for construction control is feasible.(4) The least squares method for girder self-weight identification is presented. On the basisof the least squares method, and combined with probability theory and mathematical statisticstheory, the probability analysis method for girder self-weight identification of prestressedconcrete cable-stayed bridge is proposed, so as to provide an effective method for determining the statistical characteristics of the result of girder self-weight identification and obtaining theprobability of the girder self-weight identification within different identification accuracies.With the probability analysis of the girder self-weight identification of Ganzhuxi Bridge, thetype of probability distribution and statistical characteristics of the girder self-weightidentification result of Ganzhuxi Bridge are determined, and the probability information withdifferent identification accuracies are acquired too. That proves that the probability analysismethod for girder self-weight identification is feasible.(5) Several common methods for optimization design are presented in detail. Andcombined with the characteristic of construction error adjustment, an analysis method for cableforce adjustment in the process of construction, which based on the constrained nonlinearprogramming method, is proposed. Based on that and the thought of probability reliabilitydesign method, the analysis method for cable force adjustment which based on reliabilityconstrained optimization is proposed, to provide an scientific and effective method forsearching a construction error adjustment plan meet the given structural safety reliability. Thesafety reliability of girder is taken as the constraint condition, the adjustment analysis for cableforces in the process of the construction of Ganzhuxi Bridge is developed according to theassumed construction error state. Then the adjustment plan of cable forces, which meet thereliability constrained condition and can rapidly reduce the errors of the deflexion of tower andthe elevation of girder, is obtained. It proves the method feasible.(6) According to the inner relations among the various modules of probability analysis forconstruction monitoring of prestressed concrete cable-stayed bridge, the law of data flowamong different analysis modules is explicit, thus the general framework of the probabilityanalysis of construction monitoring is established. With the example of the constructionmonitoring of17#segment of Ganzhuxi Bridge, according to the proposed general frameworkof the probability analysis of construction monitoring, the probability analysis for the wholeprocess of construction monitoring of the segment is realized.