Reliability Analysis And Safety Evaluation Of Construction Support Based On Online Monitoring

With the development of Bridges in China,the bridge system has more complex,stress,more crossing roads and more navigable rivers.As a result,the temporary structural system has been rapidly developed.Bailey-beam bracket has the advantages of large bearing capacity and no influence on traffic and navigation,which is keen on the majority of construction personnel.Although bracket support serves the permanent structure,the investment in construction occupies a large proportion.In recent years,the damage of temporary structures had caused huge losses to the whole society.Therefore,the quality of temporary structure is designed will affect the investment and construction safety of the whole project,and even affect the quality of permanent structures.Based on the continuous beam tied arch bridge of Bei jing-Xiong an Intercity Railway across Da guang Expressway,The reliability analysis and safety evaluation of Bailey-beam bracket are carried out.The main research contents and research results are as follows:（1）Accidents of temporary structures have been collected and listed in resent years,Through the analysis of a large number of cases,the causes of accidents in temporary structures are summarized.（2）The finite element model of the Bailey-beam bracket was established to analyze the safety of the bracket structure under adverse load conditions,and the safety of the bracket system design was verified.The finite element results show that the weak position of the stent is at the web bar,and it is proposed to adopt[10reinforcement treatment at the web bar.the results of the structure simulation model and the measured data was analyzed,it shows that the construction quality of support meets the safety requirements.（3）The S_AFmethod for sensitivity calculation is improved by using the first order matrix method.The improved S_AFmethod is more in line with the engineering requirements,has a wider application range and is more convenient.The improved sensitivity factor is used to analyze the sensitivity of the material and geometric factors of the Bailey-beam bracket support system.The results show that the sensitivity factors of the bracket support include the thickness of the flanges of the inclined flanges,the thickness of the web of the inclined flanges and the width of the inclined flanges.（4）The common calculation methods of reliability are summarized,and the bearing capacity of the sensitive factors of the support structure is fitted by response surface method.The failure probability of the structure calculated by Monte Carlo method is 6.486 7×10^-4,and the structural reliability is 3.216 6.The results show that the Bailey-beam bracket support meets the reliability requirements.（5）The risk identification method was adopted to analyze the controlling factors of the trestle in monitoring.The coefficient of variation method of AHP is put forward to determine the weight of evaluation indexes.The Euclidean distance method and safety grade of the Bailey-beam bracket are calculated by the Euclidean distance method as 0.094 9 and 1.05.The calculated results show that the Bailey-beam bracket is very safe.