Research On Temperature Effect Of The Main Girder Of Concrete Continuous Rigid Frame Bridge

In recent years,the socio-economic development of our country has continued,and concrete bridges,especially large-span bridges represented by prestressed concrete continuous rigid-frame bridges,have been widely used.With the engineering application of a large number of prestressed concrete continuous rigid frame bridges,there are many problems such as cracking under the effect of temperature during construction and operation.For large-span prestressed concrete rigid-frame bridges,the volume of concrete in the zero-block and other structural parts is large,and the local temperature difference is significant due to the hydration heat effect during the construction process.It may be subject to large temperature stress and may even lead to local cracking of the structural concrete,posing a structural safety hazard;In addition,the secondary stress produced by sunlight in the main beam of the structure cannot be ignored.It is necessary to deeply study the temperature effect of the main girder of concrete continuous rigid frame bridge.This paper uses a continuous rigid frame bridge as the engineering background,analyzes the hydration heat effect of the zero block and the structural effect of the main beam considering the vertical and lateral temperature gradients.The main research contents are as follows:(1)Review the relevant data,analyze the current research status of hydration heat and temperature gradient effects of concrete rigid frame bridges,and summarize existing researches on the theory of temperature effects of concrete bridges.(2)Taking the zero block of a rigid frame bridge as the research object,the physical model was established through finite element simulation to analyze the variation law of temperature field and temperature stress during the pouring process of the zero block,and the influencing factors in the process were analyzed in the hydration heat pouring.(3)Taking a continuous rigid frame bridge as the research object,the whole model and the zero block regional model were established by finite element software.The distribution patterns,considering the vertical and horizontal temperature gradient of he box girder sections were selected according to the norms and the fitting curves of the scholars at each stage of construction and at the operation stage.Considering the temperature gradient,the structural effects of the main girder and the distribution of spatial stress in the zero block area during the construction of the maximum cantilever completion phase,the completion phase of the side span closure,the completion phase of the midspan cross-section,and the completion phase of the completion of the bridge construction are analyzed.(4)In the normal operation stage of rigid bridge,considering the vehicle load,the variation law of the upper and lower edge stresses of the structural section and the displacement of the vertical bridge by considering the temperature gradient and the effect of the overall temperature increase are analyzed;and the spatial stress distribution state of the zero block superimposed with the effect of temperature is analyzed,when the area is considered to be affected by the most unfavorable car.