Stability Analysis Of Ultra-high Pier Continuous Beam In Cantilever Pouring Construction

In this paper,it takes a multi-span continuous bridge as the engineering background to analyze the stability of the supertall pier continuous beam during cantilever construction.Midas finite element software is applied to analyze the structural stability under the most unfavorable conditions during cantilever construction,taking into account the most unfavorable loads such as wind load,dead weight,temperature effect and construction machinery load.(2)In this paper,the characteristics and solutions of general stability problems are introduced,and it shows the differences between the contents need to be considered and the general stability problems in the stability analysis of continuous bridges,and also put forward the relevant solution.The content and method of stability control of supertall pier continuous bridge during cantilever construction are studied,and also analyzed the most unfavorable state and the most unfavorable load combination during cantilever construction.(2)Finite element software is used to analyze the stability of three most unfavorable conditions that may be encountered during construction.The analysis results show that the linear stability of the structure is determined by the first mode under condition 2,with the critical load factor of 14.3 and the buckling direction along the bridge direction.The stability of the non-linear effect is determined by condition 2.The critical load factor is 8.1 and the buckling direction is along the bridge direction.However,the value decreases by 43.4%compared with the linear critical load coefficient,which indicates that non-linearity has a great influence on the stability of super-high pier.The influence of non-linearity on the structural stability should be fully considered in design and construction.(3)Taking the method of controlling variables,the sensitivity of each load to the stability of super high pier continuous beam bridge is analyzed,the final finite element analysis results show that the pier height is the most important factor affecting the stability of cantilever construction process of super-high pier whether linear or nonlinear.When the pier height is increased by 30 m,the linear stability decreases by 13%.Wind load has the least effect on the structure stability.Temperature difference has little effect on the stability.When the sunshine temperature difference is increased by 5C,the structure stability decreases by about 7%.The influence of temperature difference on stability is mainly reflected in the sunshine temperature difference of pier.The sunshine temperature difference and day-night temperature difference of box girder have little effect on structure,and the construction and calculation process can be neglected.When non-linearity is not considered,the pier height changes from 56 m to 176 m and the stability decreases by 75.6%;when non-linearity is considered,the stability decreases by 84.6%.It shows that non-linearity will reduce thestructural stability,but the reduction rate will increase with the increase of pier height,which can be met by other factors such as sunshine temperature difference.