Practical Calculation Method About Stability And Displacement On The Top Of High Pier Considering Influence Of The Foundation

This dissertation is in the background of the sub-topic Pier Form Comparison andStability Research of Mountionous Bridges, which is one of the R&D projects taken byCCCG The Key Technologies of Resource-saving Research in Mountainous HighwayConstruction. The high pier stability analysis and horizontal displacement theory is mainlyused to seek the sensitivity parameters and their regular pattern of impact on high pier stability.Taking the influence of foundation on the high pier stability into consideration, by the meansof horizontal displacement calculation method, and relying on the data collected by innermodel test and monitoring at the project site, the method of the stability analysis, piercalculated length and horizontal displacement calculations is verified.Based on the domestic and foreign presdent situation and development of stabilityanalysis theory and horizontal displacement calculation method on bridges, the calculation ofstability calculation and horizontal displacements in the high pier bridge has importantsignificance. Especially the length factor has great impact on increasing eccentricitycoefficient. Compared with British and American norms, the existing bridge specification inChina is not only sketchy, and the value of the safety factor is not included. Designers oftenuse their experience to calculate, so that it is easily to be radical or conservative in designinghigh pier; while pier top horizontal displacement calculations have big differences among thevarious calculation methods.This paper reviews the development and research statust of the pier stability, horizontaldisplacement and the pier type on selected bridges, and sort out different types and cablesystem bridge combed on12kinds of pylon pier bridges. Investigation of the practicalapplication of high bridge pier6highway completed in recent years in our country is taken,and based on a statistical analysis of817samples of high pier213bridges, summarize thesuitable height interval of4common pier type.In this paper, energy method is used to derive the solving the equation of high pierconstruction stage and operation stage of the pier top weight concentrated vertical loads ofcritical buckling load. Through four types of pier type in different parameters, different heightof pier under the conditions of the stability analysis, the pier one order stability coefficient in50to60meters range decreases quickly, the height between60tand90meters is in flat region.The pier under the action of a concentrated load, the same height distribution under different pier stability coefficient size is dispersing; thin-walled hollow pier stability coefficient ishigher than other three kinds of pier type, especially between the60and90meters. Based onthe project, two kinds of stability analysis is taken and results showes that considering twokinds of nonlinear effects, the calculation results are lower than the values, the linear stabilityanalysis result is not conservative, the ultimate bearing capacity is limit; nonlinear stabilityanalysis of the steady line number is greater than1.58, which meets the safety requirements;and the number of beams in double column pier in-plane stability is monotone increasing.This paper studies that under different boundary conditions, calculated length of highpier methods are put forward under different conditions of high pier calculation lengthcoefficient. Considering the geometric nonlinear pier, pier under different boundaryconditionsare derived first order calculation equation for destabilization critical force, usingEuler formulacalculation length coefficient. Under the elastic foundation, pier pier conditionscalculated length andstandard deviation is0.65%; under the bridge into a rigid foundationpiers calculatedlength and standard deviation is less than1%; elastic foundation pier bridgestatecalculation length and standard length, deviation is less than0.5%, and this formula isverified.The shape function is given in this paper, a method to calculate the horizontaldisplacement of high pier is set up. Based on the principle of potential energy, thedisplacement of pier top are analyzed. Different boundary conditions of high pierdeformation,a method to calculate the horizontal displacement of high pier is also given.According to the given different mechanical models of boundary conditions of the pier shape,fThe method is derived for elastic constraint conditions, no formula for calculating the piertopconstraints under various conditions such as the horizontal displacement of the top of pier.And on the basis of rigid foundation,a practical formula for calculating the horizontaldisplacement of high pier is proposed for a constraint pier on the top.The research achievements not only provide technical support to determine thereasonable range, high pier bridge form and stress state in the stage of bridge designing, butalso provide the basis for the revision of the relevant sections for specification.