Research On Monitor Parameters And Safety Index Of Composite Structure Bridge

In the twenty-first century,China has seized the opportunity of changes in the world'spattern and has developed rapidly.To meet the rapid economic growth needs for transportation,China strives to develop infrastructure construction.As a stride structure across the extreme terrain,the bridge has also become a very important part of the national infrastructure construction as well as the throat of the lifeline engineering.However,with the increasing number of bridges in China,dangerous bridges have become a problem that cannot be ignored.According to incomplete statistics in China,by the end of 2016,the number of highway bridges in danger has grown to 1/8 of the total number of highway bridges,and the bridge accidents have occurred repeatedly.Hence,it is obvious that grasping the health status of existing bridges accurately is very important for ensuring the safe operation of highway network system.This paper mainly analyzes the safety indexes of existing bridge structures.The existing bridge safety indexes mainly include structural target reliability index for bridge reliability evaluation and structural monitoring and warning index for bridge health monitoring.This paper analyzes and determines the two indexes respectively.The main achievements of this paper are as follows:(1)Analyze domestic and foreign regulations on the reliability index of existing bridges,and compare the merits,demerits and applicability of different recommended values.According to the ALARP principle and the 85% guarantee rate principle,the acceptable minimum target reliability index is determined.Then,the deterioration model of the bridge's reliability proposed by Markoff is applied to the target reliability index,and the target reliability index of the existing bridge with time variation is obtained.(2)The harms of different structural type bridges are counted,and the dangerous parameters corresponding to various bridge harms are analyzed.By comparing with the mainstream monitoring parameters in existing bridge health monitoring system and the dangerous parameters of the dangerous bridge,the existing bridge health monitoring parameters are supplemented.It is found that the monitoring of the interface relative slip of steel beam-concrete slab of composite structure bridge is not involved.(3)The interface relative slip of the steel beam-concrete slab of the composite bridge is proposed as a monitoring and warning index,and a combined structural bridge model isestablished by the finite element software ABAQUS CAE.The relationship between the interface relative slip and the number of the yield stud is calculated,and the regularilies between the number of yield stud and the different interface slip amounts is determined.At the same time,the health condition of the bridge is determined,and the composite structure bridge health monitoring system is established,which take the interface relative slip between the steel beam-concrete slab as the monitoring and warning index.