Health Monitoring Technology Research Of Zhengzhou High-speed Railway Station Track Beam Structure

Zhengzhou high-speed railway station is located at Zhengzhou New District and is so far one of the largest transportation hubs in China. Its track beam adopts a structure with "combined steel and concrete column, bidirectional pre-stressed concrete frame box girder and cast-in-place concrete floor", which is employed in domestic high-speed railway supporting bridge for the first time and transcend the structure adopted in traditional single-track bridge.The essay would focus on researching the dynamic change rule of pre-stressed track beam under the force of moving train by taking the structural features of Zhengzhou high-speed railway station as a specific example. By installing fiber Bragg grating sensors at key positions on the track beam and constructing simultaneous dynamic monitoring sensor network, corresponding statistics when trains pull in or depart the station could be collected. Simultaneously monitor the corresponding changes of key sections under the force of different train loads, process statistics by writing MATLAB programs, then draw a time curve line and analyze the influence of moving train load on the structure when the train pulls in or depart the station. During one-year period, nine different load modes of trains were captured and some basic rules could be concluded after analyzing statistics recorded by installed sensors.(1) Distortions of structure are apparently symmetrical when the train pulls in or departs the station; the structure shows periodic distortion and the amplitude is determined by the total weight of train and passengers; the distortion period is in negative correlation with train speed and the statistics during the train’s arrival at station are determined by the position of train wheels.(2) Compression strain occurs at upper part of the section, tensile strain at lower part of the section while basically no distortion occurs in or near the middle area. Thus, it can be inferred that the middle area bears sagging moment while support section shows apparent symmetry with middle section.(3) Sensors on sections of girder, secondary beam and transverse girder all monitored corresponding changes. Thus, it can be deduced that train load is imposed on track board, part of which is transferred along girder to columns at both sides and part of which transferred to transverse girder. The transfer direction of force is clear and definite in the structure.(4) Pre-stressed box girder structure is adopted in transverse girder, whose ends near supporting columns are solid while middle area is hollow. Minor changes are monitored on its key section which means neighboring tracks have little influence on each other.Comparison is made between the modeling calculation by using ABAQUS software and the change rule of track beam structure when the train pulls in and departs the station. And the result indicates that FBG sensor can accurately monitor changes of every section on the track beam and actually makes the simultaneous and dynamic monitoring of the distortion of track beam under external forces at Zhengzhou high-speed station possible. The track beam shows preferable flexural behavior under the force of moving train load.