Ultra-high Pier Verticality Prediction And Control Method Based On Unscented Kalman Filter

At present,the ultra-high pier continuous rigid frame bridge is not uncommon in the southwestern mountainous areas of China.The verticality control of ultra-high piers during construction is a key link in the construction of the entire bridge.The verticality control directly affects the stress state of the pier and even affects the internal force distribution of the entire bridge structure.At present,the research on the factors affecting the verticality of ultra-high piers is relatively simple.Most of them only theoretically analyze one or two influencing factors,and lack comprehensive consideration of factors such as initial defects,sunshine temperature difference and wind load,It is difficult to accurately control the verticality of the pier.The commonly used pre-bias method and other verticality control methods are relatively simple.The vertical model index is not clear in the control process,and there are problems such as insufficient correction amount or excessive correction amount,which leads to poor construction quality of the pier and even fails to meet the specification requirements.Aiming at the above problems,a new super-high pier verticality construction control method is proposed.Based on the principle of unscented Kalman filter,the theoretical formula of ultra-high pier deflection is established.This method can greatly reduce the influence of human error and measurement error on the vertical mold coordinates of the pier section,so as to accurately control the verticality of the ultra-high pier,and provide new technical methods and means for the construction control of the ultra-high pier of the continuous rigid frame bridge.The main research contents and conclusions of this paper are as follows:(1)The effects of initial geometric imperfections,wind loads and sunshine temperature loads on the deviation of ultra-high piers are analyzed.Firstly,under the premise of considering geometric nonlinearity,the finite element software MIDAS is used to analyze the influence of initial defects on the verticality of ultra-high piers and make qualitative judgment results.Secondly,the equilibrium differential equation is established by the equivalent static wind load method,and the formula of ultra-high pier deviation under the influence of wind load is derived,and the measured data is used for quantitative analysis.Finally,the influence law of the cross-section temperature difference on the ultra-high pier deviation is studied.For the two different temperature difference gradient modes,linear temperature difference and nonlinear temperature difference,the formula of ultra-high pier deviation is deduced and compared.(2)Deducing the theoretical formula of the ultra-high pier deviation under the influence of comprehensive factors.In order to comprehensively consider the effects of initial defects,wind loads and cross-section temperature differences,the wind load is statically equivalent,and the linear shape of the pier formed by the linear solar temperature difference is combined with the initial defects.Based on the mechanical principle,the formula of the deviation of the ultra-high pier under the influence of comprehensive factors is derived,which lays a theoretical foundation for the super-high pier vertical construction control.(3)An ultra-high pier verticality control method is established based on unscented Kalman filter.Establishing a state space equation based on the formula of the ultra-high pier deviation theory,The height of the pier is regarded as the state quantity,and the deviation of the pier is regarded as the observation measurement.The construction height of each stage is regarded as the control quantity,temperature,wind speed,etc.as the input quantity.Therefore,the ultra-high pier construction process is given the concept of a nonlinear dynamic system.The unscented Kalman filter technique is introduced to construct the super-high pier verticality construction control method.(4)The proposed verticality construction control method is applied to the construction of an ultra-high bridge pier.Practice shows that the maximum deviation of the pier body is only 6mm,which is three times lower than the traditional control method.