| Structural health monitoring is one of the key technologies to ensure the safe operation of long-span Bridges.It can provide measured data and evaluate the response of bridge structures.But the bridge structural health monitoring data is often affected by many factors comprehensive results,especially the influence of temperature on long-span Bridges are particularly evident,day and night,short-term changes in temperature and temperature for a long time of the year will cause deformation of the structure of the bridge and the influence degree comparable to daily operation of the vehicle load,seriously affecting the reliability of the structure of bridge safety assessment.Arch has become the main form of long-span bridge in a long period of time because it can convert vertical load into pressure,and its shear value and bending moment are both smaller than those of beam with the same span.With the emergence of new ideas of structural construction and design,box bridge has become the most widely used bridge structure at present.Based on the long-term data of temperature and displacement in the structural health monitoring system of a long-span steel box girder arch bridge,the temperature field distribution of the longspan steel box girder arch bridge is studied,and the correlation between temperature and displacement is discussed.The main research contents of this paper are as follows:(1)Based on the long-term temperature monitoring data recorded by the structural health monitoring system,the variation of short-term and long-term temperature of long-span steel box girder arch bridge is studied.Taking 24 hours as the time scale,this paper selects the representative days of spring,summer,autumn and winter respectively to analyze the short-term temperature variation in detail.The results show that the short-term temperature variation law is similar to sine curve,and the short-term temperature variation law within and between components is analyzed.Using April-December of the year in 2013 long-term actual monitoring data of temperature,the temperature change rule has carried on the detailed analysis for a long time,summarizes the change law of temperature for a long time,and analyzes the components and components in long-term temperature difference between the change law of the long span steel box girder arch bridge by using probability statistical analysis it is concluded that the temperature effect of the model.(2)Based on the measured data of temperature and displacement,the image characteristics,generation mechanism and compensation method of time-delay effect of temperature and displacement of long-span steel box girder arch bridge are studied.Based on the characteristics of the measured temperature-displacement correlation images,the time-delay images are classified and their laws are discussed.Based on the synchronous characteristics of temperature variation of arch rib,hanger and steel box girder with vertical displacement and expansion joint displacement,the formation mechanism of temperature lag is discussed.Then,based on the time delay between temperature and temperature induced displacement,it is realized that there is a phase difference between them.By Fourier transform,the temperature and temperature induced displacement are transformed from time domain to frequency domain,so as to identify the phase difference between them and eliminate the delay effect by translation.(3)The feasibility of artificial neural network method for prediction of temperature induced displacement of long-span steel box girder arch bridge is discussed.Based on an example of a long-span steel box girder arch bridge,a suitable artificial neural network model is established by using MATLAB programming language and neural network algorithm to predict the temperature induced displacement.The results show that the prediction effect has high precision and reliability,and the program can be used to predict the temperature induced displacement of long-span Bridges. |
PDF Full Text Request