Research On Reliability Index Of Steel Main Girder Of Long-Span Cable-Stayed Bridge Based On Cost-Benefit Analysis

The basic task of structural design of cable-stayed bridges is to meet the structural and functional requirements with reasonable reliability.The reliability problem runs through the entire service period of the structure.To ensure the safety and reliability of the structure within the design life,it is necessary to make the structure in service period.The reliable index is not less than the target reliability index.Therefore,it is of great theoretical and practical significance to study the reasonable value of the reliability index of cable-stayed bridge structure design.Based on the existing theory and research,this paper makes a deep research on the reasonable value of the reliability index of steel main beam target of long-span cable-stayed bridge by cost effect analysis.The main results are as follows:(1)Based on the research of reliability index of structural target based on cost-benefit analysis method,the calculation and analysis process of determining the reliability index of steel main beam target of long-span cable-stayed bridge by cost-benefit analysis is proposed.(2)By comparing the cost calculation models of the bridge life cycle of the bridge structure at home and abroad,and converting the various expenses into the net present value according to the discount rate,the objective function of determining the target reliability index based on the cost benefit analysis method is determined,that is,the initial construction cost,The minimum of the sum of the maintenance and repair costs and the net present value of the cost of failure,and a calculation model for estimating the initial construction cost based on the percentage of the construction cost of the failure cost.(3)The ultimate bending capacity bearing capacity attenuation model and the time-varying live load effect of the main girder under the action of the load and environment of the steel girder of the cable-stayed bridge are determined.Based on this,the checkpoint method is used to solve the long-span cable-stayed Failure probability of bridge steel main beam under different service periods.(4)Taking a cable-stayed bridge as an example,when the discount rate is 0.08,the cost reliability analysis determines that the target reliability index of the main beam of the bridge steel in the industrial atmosphere is 6.602,and the main beam is calculated under different atmospheric conditions.The recommended value of the target reliability indicator when the discount rate is different.