Research On Spatial Temperature Effect And Creep Mechanism Of Steel Box Concrete Composite Curved Girder Bridge

In recent years,with the development of urban traffic,steel box concrete curved composite girder bridge is widely used in urban interchange and expressway interchange.However,curved girder bridges are prone to creep.In order to prevent and control the creep of curved girder bridges,it is necessary to study the creep development law of steel box-concrete curved composite girder bridges.The existing research shows that temperature load is the main factor causing creep of curved girder bridge.However,there is no analysis on temperature field distribution and law of long-term creep of steel box-concrete composite girder bridge.In view of this,based on the bridge sunshine temperature field simulation method,this paper carries out fine temperature field analysis for steel box-concrete composite beam bridge and long-term creep analysis for steel box-concrete curved composite beam bridge.The main work of this paper is as follows:1.Relevant theories of bridge sunshine temperature field simulation are systematically elaborated,including heat conduction principle of bridge structure,various types of radiation such as direct solar radiation,scattering radiation,atmospheric inverse radiation and their calculation formulas under natural environment,convection heat exchange principle between bridge structure and external environment,and three-dimensional solar radiation shielding theory proposed in previous research of the subject team.The realization method of bridge sunshine temperature field simulation in finite element software is explained.2.Taking a 72 m simply supported steel box-concrete composite beam bridge under construction as an example,the temperature distribution characteristics of the composite beam under typical weather conditions in all seasons are analyzed by using the simulation method of sunshine temperature field of the bridge.The vertical temperature gradient of the composite girder bridge with two modes is proposed.Four temperature difference bases and three position bases are used to simplify the vertical temperature gradient of the two modes.The influencing factors of temperature distribution of the composite girder bridge are summarized and the influencing laws of each influencing factor on the vertical temperature gradient are analyzed.The accuracy of this method is verified by the temperature field test of steel box concrete curved composite girder bridge.3.In view of the lack of long-term creep analysis of curved girder bridges in current research and the insufficiency of neglecting the influence of friction slip of bearing in creep analysis,long term fine temperature load simulation method and bilinear support simulation method are applied to analyze the temperature load,short-term temperature effect under vehicle load and long-term creep of a steel box-concrete curved composite girder bridge under construction.The influences of design speed,support arrangement and curve radius on the creepage of curved girder bridge are analyzed.