Application Of Multi-failure Mode Probabilistic-non-probabilistic Mixed Reliability Model In Bridge Strengthening And Evaluation

There are many uncertain variables and failure modes in the bridge system,and there is a high correlation between failure modes,the existing single uncorrelated failure mode reliability calculation can not meet the reliability evaluation of bridge system.Therefore,it is necessary to establish a hybrid reliability model which can analyze multiple failure modes and apply it to bridge evaluation and reinforcement.This paper takes a continuous rigid frame bridge as the research object,studies the application of the mixed reliability model of multiple failure modes in practical engineering,and obtains the system reliability of the continuous rigid frame bridge.First of all,based on the field measured parameters,combined with the construction drawings and other data,using the finite element software MIDAS to model the bridge,using the global critical strength branch approximate bound method to carry out the finite element analysis of the model,to find the main failure mode.Secondly,the sensitivity of the measured parameters is analyzed,the key parameters are selected,and the quadratic polynomial response surface without cross term is constructed to solve the failure mode function.Finally,the reliability of the existing continuous rigid frame bridge system is calculated by using the probability interval mixed reliability analysis method with multiple failure modes and considering the correlation of each failure mode,and compared with the reliability obtained by the probability reliability method.The results show that the method adopted in this paper has fewer calculation times and is more conservative than the probability reliability method,which can ensure the safety of the structural system.Based on the above results of reliability calculation of continuous rigid frame bridge system,an improved grey correlation failure tree analysis method is proposed by combining it with the grey correlation fault tree analysis method.The results show that this method can effectively reduce the analysis error caused by human factors.At last,the dynamic early warning system of assessment and reinforcement of existing bridges is put forward,so as to achieve the purpose of dynamic maintenance of "continuous monitoring,safety analysis,risk early warning,reinforcement and renovation,and continuous service" of existing bridges.According to the example verification,the main conclusions are as follows: it is feasible and effective to introduce the mixed reliability analysis method of multi failure mode system into the evaluation system of bridge system,which enriches the evaluation system of bridge;he correlation among failure modes of bridge system is very high,so it is very important to consider the correlation of failure modes in hybrid reliability analysis.