Analysis Of Temperature Field And Effects On Concrete Curved Box-girder Bridges

Curved girder bridges are widely used as connections for different types of roads.The curved girder bridge is also an important component of urban expressways.The analysis of temperature field and its effect on curved bridge is the theoretical basis for its long-term safely use,which can promote the stable and safe operation of the curved bridge in complex various temperature conditions.The high-quality development of China’s bridge industry also puts forward higher requirements for the design of curved bridges.This paper studied the temperature field and its effect on the curved concrete box girder bridge.The paper mainly develops and completed the work as below.(1)Firstly,the paper summarized the types,characteristics and existing problems of curved girder bridges.In addition,this chapter classified and summarized some of the conclusion from the studies about the temperature field and its effect on curved girder bridge.Also,this Chapter introduced the methods of temperature field calculation in domestic and foreign standards.In addition,the basic method of creating a temperature field by finite element software is introduced.(2)Secondly,the paper introduced a temperature experiment project.By comparing the stimulated temperature field data with measured data,this chapter verified the effectiveness of the method of simulating temperature field in using finite element software.What’s more,the method was used in a project of a three-span continuous curved girder bridge,which is established by C50 concrete.Box section is used in the curved girder bridge.Using ABAQUS to establish a solid finite element model with the experimental bridge.Using the measured temperature conditions of 14 hours and a temperature drop of 5°C as the control,ABAQUS was used to simulate the temperature field exactly the same as the real temperature conditions and calculate the vertical bearing reaction forces of the eight bearings of the curved girder bridge.By comparison,the bearing reaction forces of the eight bearings of the curved girder bridge simulated by ABAQUS is in good agreement with the measured data.Therefore,the effectiveness of temperature effect simulation is verified.(3)The study simulated the complete process of uniform temperature drop of 5°C.The variation of the reaction force of the curved girder bridge bearing was calculated in two horizontal constraint stiffness condition.One condition is that the 8 bearings of curved girder bridge have the horizontal constraint stiffness and another condition is that those bearings do not have the horizontal constraint stiffness.The study found that the effect of temperature field on curved girder bridge is subject to the temperature field conditions and the ability of releasing temperature deformation.When the horizontal constraint stiffness of all 8 bearings were set zero in finite element software,the temperature deformation could be released.At this condition,the vertical bearing reaction forces of 8 bearings of curved girder bridge would still show the trend of increasing first and then decreasing,though.In addition,the largest vertical reaction force occurred during the cooling process.When the process of temperature cooling was complete,the vertical bearing reaction forces of all 8 bearings were approaching zero.When the bearings had horizontal constraint stiffness,the vertical reaction force showed a trend of increasing as the process of temperature cooling and the largest reaction force appeared in the end of the cooling process.Therefore,the process analysis should be considered when the temperature deformation could be released,because the full effect of uniform temperature drop may be underestimated if we do not consider the process condition.(4)The study simulated the bearing reaction forces and displacements of 8 pot bearings of the model curved girder bridge and straight bridge in using ABAQUS.The straight girder bridge is consistent with the curved girder bridge except that it has no radius.The study found that the pot bearings could not release temperature deformation well and the largest reaction force would appear during the process of temperature cooling.When the cooling process was complete,the pot bearings of curved girder bridge still contained large reaction force,while the straight girder bridge could release the displacement better than the curved girder bridge by comparing the results of the two bridge model in ABAQUS.The largest reaction force of the straight girder bridge appeared in the process of the cooling and disappeared when the cooling is complete.The displacement of pot bearings got its largest value at the end of the cooling process.Therefore,the effect of uniform temperature drop of 5°C not only contains the displacement effects,also contains the bearing reaction forces of traditional bearings-layout which cannot disappear when cooling is done.In addition,the study found that the diaphragm beam improves the overall rigidity of the curved girder bridge and can make the bearing reaction force and the displacement of the curved girder bridge more balanced.What’s more,the study also found that the radius of the curved girder bridge tends to become smaller and the curved girder bridge will tend to twist inward when the temperature decreases.