| The existing railway ?-section RC beams have been in service for many years.Because of the influence of train load and environmental factors,the early low design standards,and the concept of vascular management is behind,with the aging of concrete and reinforcement materials of the beam body,resulting in frequent occurrence of disease.The structural resistance is constantly attenuated,leaving hidden dangers for the safe operation of the line.For this purpose,for the disease-prone cross-section beams currently in service,the disease characteristics are analyzed through field investigation,the failure mechanism is analyzed,the bearing capacity reserve is calculated,and the law of the bearing capacity degradation of the disease beam body is analyzed,thereby providing reliable maintenance,The reinforcement of technical means has become an urgent task.This article relies on the Lanzhou Railway Bureau's scientific research project "Ribbed Defects Bridge Assessment and Maintenance Technology Research",on the basis of field surveys on the part of the Lanzhou-administered bridge-shaped beam,combined with regional environmental characteristics,analysis of its disease characteristics and causes;The influence of the disease on the bearing capacity of the beam body was studied by means of calculation and finite element simulation.The main contents of the study are as follows:(1)Field surveys were conducted on the beam profile of some railway lines under the jurisdiction of the Lanzhou Railway Bureau;on the basis of the analysis of survey data and analysis of inspection data,the typical disease characteristics of existing beam beams were summed up;The environment,bridge microenvironment and structural characteristics of the site were analyzed,and the causes of various diseases were analyzed.(2)According to the relevant regulations,the load capacity of the existing truss girder during design is calculated and analyzed,and the force characteristics of the girder under the effect of the existing passenger and cargo collinear loads are also checked.At the same time,it is feasible to operate heavy-duty trains.Sexual analysis was performed.(3)The numerical simulation method was used to analyze the influence of concrete cracks between beams and beams,and the effect of vertical cracks in the beam body on the bearing capacity and stiffness of the beam.At the same time,combined with engineering examples,the beam was affected by corrosion of the main reinforcement.Force characteristics.(4)Combining domestic and foreign relevant specifications and literature,the influence of steel bar corrosion on the bearing capacity of the beam body was analyzed;and according to the requirements of the railway certification code and the characteristics of the multi-layered bar structure of the ?-shaped beam,the rust corrosion applicable to the existing railway was proposed.The calculation formula for the flexural capacity of shaped beams.(5)Discussed and analyzed the commonly used methods of repairing concrete beams.Combining with the characteristics of the load-bearing reinforcement of railway bridges,numerical simulation methods were used to analyze the main issues in the maintenance of beam bodies and the construction of paste reinforcement. |
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