Research On Safety Evaluation System Of Lightweight Bridge Crane Structure On On-line Monitoring

In the long service process,bridge crane often causes dangerous accidents because of corrosion,fatigue and other structural damage,and even causes huge personal and property damage.This requires the establishment of structural safety assessment system for bridge crane,to real-time monitor structural status,early identify structural damage and give safety warning tips.With the extensive research and application of lightweight technology on bridge crane,considering the influence of lightweight design on the safety performance of crane,in order to better ensure the safe use of lightweight technology,the structure of lightweight bridge crane safety monitoring and evaluation are even more important.The paper uses lightweight bridge crane as a research object,abandons the traditional method of the strain gauge monitoring,and uses fiber grating sensing technology to build the structure on-line monitoring and safety assessment system.Through the processing and analysis of the collected monitoring data,time series prediction model and control chart damage identification algorithm of structural stress are established,which makes the safety evaluation system can carry out long-term on-line monitoring and effective early warning of the lightweight bridge crane.The main contents and achievements of this paper are as follows:(1)Through the comparative analysis of different online monitoring methods,the paper selects fiber grating sensor as online monitoring system's sensor component.Time series analysis method is introduced into the monitoring data analysis of lightweight bridge crane structure,which leads to the safety evaluation method based on timing prediction and control chart.(2)In order to determine the position of fiber grating sensor's measuring point,finite element analysis of the lightweight bridge crane is carried out,and the positions of measuring point are determined according to the finite element calculation results.According to the modeling step of time series model,the ARMA prediction model is established for a group of structural stress data of lightweight bridge cranes after pretreatment.The prediction result shows feasibility of forecasting method based on the time series analysis in the prediction of the lightweight bridge crane's structural state.(3)In the application of control chart to crane structure's damage identification,an optimized EWMA control chart is proposed as the algorithm of damage identification considering the autocorrelation between time series,and the effectiveness of the algorithm is proved by simulation.Under the premise of damage calibration criterion,structural early warning threshold early warning mechanism are set up by combining control limit of control chart,finite element analysis result of the most unfavorable condition and the structural allowable stress,and applies it to the studied lightweight bridge crane.(4)The overall framework of lightweight bridge crane safety assessment system is constructed,the key hardware equipment fiber grating sensor and fiber grating demodulator are selected and analyzed.In addition,based on C # programming language and SQL Server database,function module design and realization and application of the safety evaluation system software are carried out.