Rearch On Creeping Problem Of Full Torsion-supported Curved Beam Bridge Based On Finite Element Model Updating

Due to the influence of the radius of curvature,curved beam bridges are in the bending-torsional coupling,unbalanced supporting force of internal and external side,and other complex strenuous condition.Coupled with the lack of relevant design specifications,lack of understanding of the difference between the bending and straight bridge,and the subjectivity of empirical design,the curved beam bridges of early designed and even new structures appear creeping phenomenon in varying degrees,and often induce the pier body cracking,bearing empty,the main beam overturned and many other diseases,which affect the appearance of beauty,reduced comfort of driving or lead to serious collapse of the bridge and other security incidents.Based on the Panjiawan EK0 + 138.873 Ramp Bridge,considering the dynamic accumulation process of the main beam creeping,the paper introduces the idea of finite element dynamic updating in the analysis of full torsion-supported curved beam bridge,and puts forward the reasonable control standard of displacement of main beam and bearing and the shear deformation of bearing,meanwhile proposes the effective prevention and mitigation measures of creeping on the basis of detailed analysis of supporting factors.This paper mainly includes the following research contents and conclusions:(1)Based on the dynamic and static load test of bridge,the joint static and dynamic finite element updating method based on dynamic coefficient is put forward by considering the“joint“ effect of static and dynamic response,and the initial beam grid model is applied.The results show that the finite element updating technique of combined static and dynamic can reduce the error of each target response value and the measured value by half.Compared with the conventional joint static and dynamic updating method,the method is more accurate and perfect,with significant advantages and promote the application of value.(2)Based on the modified finite element model,the influence of the overall creeping of the main girder and slippaget and shear deformation of its bearing on the structure is analyzed.The results show that the radial displacement of the main beam is consistent with the influence of the longitudinal offset on the response values,but the influence degree is about several times or more,which should be controlled by the radial effect control.The creeping and the joint disease,which is represented by shear deformation,makes the structural response multiplied by a few times or even several times,and the influence on the edge of the pier and its bearing is the most unfavorable.It is necessary to determine the single-index limit of the radial displacement of the main girder,the bearing offset and the shear deformation,and put forward the reasonable control recommendations.Based on the above analysis,the mechanism of creeping is further refined and perfected,and the detailed explanation is given.(3)The contribution of centrifugal displacement and temperature load to the radial force of the structure is calculated by using the finite element model.,which shows the centrifugal force and the temperature load are the main external factors.Based on the principle of force method and virtual work,the formula of radial displacement of arbitrary section considering the effect of shear under the centrifugal force and uniform temperature is deduced.The correctness and validity of the proposed formula are verified by an example.Furthermore,the characteristics of the radial displacement analysis formula are analyzed,and the key influencing factors of the creeping are the radius of curvature,the center angle,the section characteristics,the supporting method and the bearing arrangement.The prevention of the creeping disease should focus on the reasonable value of the four factors.(4)Through the analysis of the supporting arrangement factors,the influence rule of the bearing spacing,the pre-eccentricity of the intermediate bearing,the form of the support and the bearing on the structure are obtained,and the relative optimal setting scheme of each project is determined.And the effective mitigation measures such as increasing the spacing of the bearing,pier-beam consolidation or double-pier layout,plate-type bearing replacement for the basin-type bearing,the set of limit devices and other effective mitigation measures between pier and main beam are proposed,also the detailed layout requirements and recommendation of each set are given.