Research On Displacement Measurement Method Of Railroad Bridge Piers Based On Fusion Of Multiple Acceleration Sensors

With the early bridge construction climax of the retraction part of the existing structure is gradually reaching the service life and,and the railway freight volume continues to increase and the transport speed continues to improve,the bridge pier stiffness can’t match the current safety of the railway operation problem is becoming more and more prominent.Therefore,under the condition of limited railway maintenance cost,how to improve the structural health monitoring(SHM)technology conveniently and effectively is a problem that every bridge engineer must consider.The displacement of bridge piers under the train crossing event can directly and effectively reflect the performance state of bridge piers and is an important basis for the railway management department to evaluate the health state of the structure However Bridges because of its geographical environment and the height of piers has restricted the traditional displacement sensor is difficult to set up,and don’t have access to stable reference point,reduce the bulk of the displacement measurement method is practical,that for some new technology based on reference point sensor displacement evaluation method put forward more requirements Bridge researchers have been working to develop new technologies that do not depend on good weather conditions and are not limited to short-term monitoring.These technologies need to be able to monitor the condition of Bridges in real time to provide continuous,real-time and reliable data for the bridge health monitoring network.This paper discusses a multi-degree-of-freedom and reference of free displacement estimation method based on the acceleration sensor fusion technology,which is mainly aimed at the transverse total displacement of the pier top of railroad bridge piers with low stiffness.In this reference of free displacement estimation method,the total lateral displacement of pier roof is decompose into two parts:(a)the high-frequency dynamic displacement component generated by the train wheel-rail interaction,whose frequency range is mainly concentrated above 0.5Hz;(b)The low-frequency pseudo static displacement component generated by the stress and deformation of bridge piers mainly concentrates in the frequency range of 0～0.5Hz.Finite impulse response(FIR)filter is used to extract dynamic displacement acceleration data with frequency above 0.5Hz.The dynamic mean(SMA)filter is used to extract the pseudo static displacement components with frequencies ranging from 0 to 0.5Hz.In this paper,the method was verified by a shaking table experiment,and two quantitative parameters were proposed to evaluate the accuracy of the proposed method in both the peak displacement estimation and the overall displacement estimation.The accelerometers used in the experiments were both models produced by PCB Piezotronics.Shaking table experiment of 3711E1110G DC response accelerometer is divided into two parts:one is to use the accelerometer to estimate the displacement of the two-degree-of-freedom model,the other is to use the accelerometer to estimate the displacement of the four-degree-of-freedom model.By comparing the experimental results of quantitative parameters under multi degree of freedom displacement estimation in both the peak displacement estimation and displacement on the estimate of the overall error of displacement estimation method is much smaller than the single degree of freedom,this means considering asymmetric boundary conditions and displacement of pier damage after many degrees of freedom without reference to estimate method has a certain practical significance,and can effectively reduce the displacement estimation error In the multi-degree-of-freedom model,there are many sensors,but only at the beginning and end of the displacement time-history curve,the noise of sensors and other electronic components is significantly affected.Due to the low noise,the displacement estimation error of the train crossing the bridge is not significantly affected.The multi-degree-of-freedom non-reference displacement estimation method based on acceleration sensor fusion technology proposed in this paper can realize real-time displacement monitoring of light railroad piers within a certain error range.This method can be used as a potential alternative to the traditional displacement meter.It does not need a fixed reference point and can be used to monitor the displacement of the structure in a wide range of frequency domain for a long time without the influence of weather and climate conditions.