Reliability Research Of Fabricated Hollow Slab Bridge Considering Lateral Connection Damage Under Random Traffic Flow

As the throat node of transportation,highway bridges play an irreplaceable role in the development of social economy.Prefabricated hollow slab bridges are widely used in small and medium-span bridges due to their light structure,simple structure,convenient transportation,quick construction,and ease of standardization and integration.However,with the rapid advancement of my country’s industrialization process,the traffic load is constantly changing and increasing.At the same time,as the service time of the bridge increases,the materials are constantly deteriorating,Under the influence of these two factors,the key parts of the existing prefabricated hollow slab bridges,especially the joints where the cast-in-situ concrete longitudinal tongue and groove joints are used as the structural transverse connections,are frequently damaged and diseased.In severe cases,"single beam stress" may occur.Extreme situations have serious hidden dangers to driving safety.In order to study and analyze the influence of lateral connection damage on the structural reliability of prefabricated hollow slab bridges under the current vehicle load,First,based on the theory of vehicle-bridge coupled vibration,a vehicle-bridge coupled vibration analysis system was established;Secondly,relying on the measured vehicle load information obtained by the Xuan-Da Expressway WIM dynamic weighing system and the linear CCD traffic information acquisition system,the characteristic parameters of the vehicle load are counted,and a random traffic flow model that conforms to the current actual operating conditions is established;Subsequently,based on the random traffic flow model,using the vehicle-bridge coupled vibration analysis system as the calculation platform,the probability distribution of the maximum traffic load effect under different damage positions and degrees of the hollow slab hinges in the design basis was analyzed and calculated;Finally,based on the reliability theory,the Monte Carlo method is used to calculate the reliability index of the hollow slab structure under various damage conditions,and the influence of different damage positions and degrees of hinge joints on the reliability of the hollow slab structure is analyzed and evaluated according to the specifications.The main research work is as follows:(1)Summarizes the transverse connection methods and characteristics of fabricated reinforced concrete hollow slabs and common diseases,and analyzes the causes of common diseases in detail from the aspects of design,construction,operation and maintenance;The commonly used method of simulating hinge joints—the grid method of virtual beam simulating joint joints is introduced.Based on the analysis of references,the rationality of simulating the joint damage of hollow slabs by using the virtual beam stiffness reduction method is deduced.(2)Based on the bridge finite element analysis software BDANS(Bridge Dynamic ANalysis System)under the effect of random traffic flow in the normal operation stage developed by the research group,the model correction technology was introduced to establish the assembled hollow slab bridge vehicle-bridge coupling vibration analysis system.(3)Based on the measured vehicle load data obtained by the WIM dynamic weighing system and the linear CCD traffic information acquisition system of Xuan-Da Expressway,the vehicle load model,total vehicle weight,axle load,vehicle speed,driving time span,and lateral position are analyzed and counted.According to the statistical distribution law of the parameters,a random traffic flow model conforming to the actual traffic vehicle load characteristics is established.(4)By analyzing the vulnerable position of the hollow slab hinge joints,delimiting different damage levels,designing different loading conditions,using the established random traffic flow model,through the vehicle-bridge coupling analysis,the bridge structure response under the random traffic flow is obtained.Subsequently,non-parametric kernel density estimation is used to analyze the section distribution of the vehicle load effect of the hollow slab bridge under different working conditions.According to the section distribution of the extreme value of the vehicle load effect,based on the calculation and analysis of Generalized Extreme Value(GEV)theory,the maximum distribution of vehicle load effects under different damage conditions within 100 years of the design reference period.(5)Based on the Monte Carlo method,the structural reliability index of the hollow slab bridge under different damage conditions within 100 years of the design reference period was calculated based on the Monte Carlo method.The influence of different damage positions and degrees of hinge joints on the structural reliability index was analyzed.The reliability performance of the slab bridge structure was analyzed and evaluated.