Reliability And Sensitivity Analysis For Construction Control Of PC Continuous Rigid Frame Bridges Based On Stochastic Response Surface

During the construction of PC continuous rigid frame bridges,due to random variations of structural dimensions,material properties and loads,deflections and stresses of main girders are difficult to meet well with ideal design state.Therefore,to investigate the construction control of bridges,stochastic response surface is introduced to reliability and sensitivity analysis in this paper.Firstly,a method to establish stochastic response surfaces for construction control is proposed in this paper.And construction parameters whicn follow nonormal distributions are successfully inputted.The advantages and disadvantages of three collocation methods are compared by a numerical example of cantilever.The result indicates that compared to Latin Hypercubes Sampling and Monte Carlo Sampling,probabilistic collocation method based on linear independent criterion is of highest efficiency.And it's easy to improve the accuracy of stochastic response surface by raising order and increasing collocation points.Secondly,by combining stochastic response surface and high order moment method based on general Lambda distribution,the probability density functions of state variables are obtained.Thus,a method of reliability analysis for deflection control based on stochastic response surface is established.In addition,to avoid complicated integral operation and improve computational efficiency,the multiple stochastic response surface method is employed to compute the failure probability of whole construction process.Thirdly,quasi global sensitivity analysis method and ANOVA based on stochastic response surface are further investigated in this paper respectively.The result shows that the computational accuracy of these two methods depends on stochastic response surfaces and the same sensitivity sequence could be obtained.The interaction of construction parameters could be measured by ANOVA,while the quasi global sensitivity analysis method is of less computation.Finally,taking Lijiawa bridge as engineering background,on the basis of determined random distributions of consruction parameters,the reliability and sensitivity methods based on stochastic response surface are applied to this bridge.The result shows that the failure probability of deflection control increases with the increment of cantilever length and decline rapidly after closure.The variations of parameter sensitivities to deflections and stresses of main girder are also remarkable.The sensitivity of control stress in prestressed tendons decreases with the increment of cantilever length,while the sensitivity of dead load increases.In addition,the moduls and compressive strength of concrete only have smaller impact on deflections of main girder.