Study On Early Temperature Stressand Crack Resistance Of Prestressed Concrete Box Girder

With its good crossing ability and the overall structure of mechanicalperformance,prestressed concrete thin-walled box girder bridge is widely used in modernlarge span bridges. However, the cracking problem has become a major problem hindering thedevelopment and application of box beam, which will not only influence the appearance ofthe structure, but also impact the safety and durability of the bridge. Studying on box girderanti-crack and crack prevention measures has become a hot issue in engineering field.Causes of cracks of box girder is complex, mainly attributed to the cause of force anddeformation effect. The early temperature stress and shrinkage are the main reasons of boxgirder cracking, and the influence of temperature cracks of box girder is maximum, which isthe early crack of box girder control point. Therefore, studying on the concrete earlyhydration heat temperature field and temperature on stress distribution, making thetemperature control measures,can effectively control the crack damage.With the theory and method of this reference to previous research on concrete crack, theauthor collect early water temperature field measurement data of a highway bridge,s30metersbox girder, and analysis of box girder in different parts of concrete early hydrationtemperature distribution and change rule of time. Differential method is used for the test ofthe box girder temperature, and the two results are in good agreement. ANSYS analysissoftware is used to carry out physical simulation calculation on the temperature stress of boxgirder bridge, and compare the results with the beam body early temperature test resultsanalysis and comparison: the hydration heat temperature and stress of end and diaphragm ofthe box beam is higher; In the same section, the temperature and stress in the webs and roof orfloor over parts is higher than other parts, which are the weak parts of key control; In theconcrete box girder of the distribution of temperature field and temperature stress research theexperimental measurement and numerical simulation method have feasibility and goodconsistency.Finally, based on the results of the study, combined with the engineering practice, makethe anti-crack measures of box beam crack from raw materials, design, construction,maintenance and other aspects, and put forward the corresponding control methods according to the characteristics of box beam crack, provide theoretical guidance for the construction ofbox girder cracking.