Study On The Cause Of Longitudinal Deviation Of Double Column Piers For Large Longitudinal Simply Supported Continuous Beam Bridge And Effect On The Mechanical Performance Of The Structure

During the thirteenth Five-Year Plan period,the highway traffic construction in the central and western regions is becoming more and more prosperous,the simply supported continuous beam bridges are widely used in mountainous expressway.The topography has a great influence on the horizontal and vertical shape of the bridge in mountainous area,and the topographic fluctuation of the cross section is very large at the bridge position,the height of adjacent piers and the height of piers in the same pier may be very large.The longitudinal slopes of bridges in many mountain highways are close to or even exceed 4% of the standard limit,pier deviation is a common disease in the later operation of this kind of bridge.In order to study the causes of longitudinal deviation of double-column piers and its influence on the structure of girder bridge with large longitudinal slope,firstly,the load transfer between the superstructure and the substructure of a large longitudinal slope bridge is analyzed in combination with the supporting engineering,and the load characteristics of the pier top of the double-column pier are clarified;secondly,considering the pile-soil interaction,the causes of the pier column deviation are analyzed based on the actual pier top load and limit factors;finally,according to the change of the mechanical properties of the upper and lower structures,the effect of pier deviation on the structure of the bridge is analyzed.The main tasks are as follows:1 Expound the research background of bridge pier deviation,collect the main research results of the simply supported continuous beam bridge and pier longitudinal deviation at home and abroad,summarize the existing problems and shortcomings,and clarify the research content of this paper;2 By changing the size of the longitudinal slope,the pier top load of superstructure under the design of live load,constant load,temperature load,shrinkage and creep are analyzed;according to the characteristics of the bridge with large longitudinal slope,based on the bimodal distribution probability model of vehicle load of highway bridge,the evaluation value of main and heavy vehicle load in the design reference period is determined,and the pier top load of vehicle under general and dense operation conditions is obtained when climbing or downhill accelerating and braking,at the same time,the influence on the pier top load is considered when bearing separation and the main beam and the support contact inequality limit factor appears;3 The ABAQUS finite element method is described in terms of the basic theory of finite element calculation,the constitutive and element properties of materials,the theory of contact analysis and the in-situ stress balance,the effect of pile and soil on the longitudinal displacement of pier is analyzed by comparing the difference between pile and soil when considering the action between pile and soil and without considering the action between pile and soil;4 The displacement of pier top is analyzed on the basis of actual pier top load from the aspects of design function,acceleration and braking of vehicle climbing or downslope,the main beam and the support contact inequality and bearing separation,and the effects of initial geometric defects,pier bias and sunshine temperature difference on the displacement of pier top are studied.In combination with the development of plastic strain of soil under unidirectional and bi-directional cyclic loads,the mechanism of pier deflection is discussed;5 On the basis of the above research,study on the safety and degradation of bridge structure after pier deflection,the moment effect of the bridge superstructure,the stability and stress performance of the substructure are analyzed quantitatively,the safety and performance of the bridge structure are evaluated after the pier column is deviated.