Research On Construction Monitoring Technology Of Long Span Prestressed Continuous Rigid Frame

With the vigorous development of China’s infrastructure,more and more areas need to build bridges with large spans.The application of long-span prestressed continuous rigid frame bridges in highway and railway construction is very extensive.Large-span continuous rigid frame bridges usually use large-volume concrete structures,and large-volume concrete hydration heat often causes crack problems.Therefore,for structural safety and durability,effective temperature monitoring of the construction of the caps is required.Long-span continuous rigid frame bridge construction,the main bridge adopts the hanging basket cantilever construction process,and the structural stress and displacement are more complicated.In order to ensure that the force and line performance of the main bridge after the bridge meets the design requirements,the construction process is strictly monitored.The actual engineering(70+130+70)m long-span prestressed continuous rigid frame bridge is the research object.The main research contents and conclusions are as follows:(1)Summarize the research status of large-scale concrete hydration heat monitoring and construction monitoring technology of long-span continuous rigid frame bridge,and determine the construction monitoring method and research content.The values and calculation formulas of the relevant parameters of the temperature control technology are described.(2)The model is established by the finite element software MIDAS/Civil,and the temperature curve of the theoretical value is consistent with the temperature curve of the measured value.The influence of the cooling pipe on the hydration heat temperature is mainly studied.The necessity of using the cooling pipe is explained by comparing the presence or absence of the cooling pipe.The influence of each parameter on the temperature monitoring is obtained by changing the different parameters of the cooling pipe,thereby improving the cooling.The cooling effect of the tube.The maximum internal temperature of the cap,the maximum temperature difference between the inner and outer surfaces,the cooling rate of the cooling pipe,and the temperature difference between the inlet and outlet of each layer of the cooling water pipe are in compliance with the specifications.(3)Summarizing the basic theory content and method of construction monitoring,combining with the actual engineering characteristics,establishing MIDAS/Civil finite element model,emphatically calculating and analyzing the stress distribution results of several key construction stages,and calculating the pre-arch results of the whole bridge.The sensitivity analysis of the main design parameters of continuous rigid frame bridge is carried out,and the least square method is used to identify and modify the main sensitive parameters.The field measured stress,deflection and theoretical calculation results of each construction stage are compared and analyzed.The actual elevation of the bridge basically coincides with the design elevation.The alignment of the bridge is ideal.The stress of the structural control section also meets the requirements.The whole monitoring effect of the bridge is very good.