Research Of Thermal Effect On Box Girder Of Long Span Continuous Rigid Frame Bridge

With the comprehensive development of highway and urban tridimensional traffic, bridge construction has entered the unprecedented golden period with the rapid development. Box girder, by its unique merits, has long been the main beam section forms. But a great number of continuous box girder bridges and continuous rigid frame box girder bridges during both construction and business processes, some serious cracks which do fatal damage for the use of bridges have been discovered and been paid more and more attention by domestic and overseas scholars, experts, the thermal stresses contribute significantly to the cracking and consequent deterioration of the concrete bridge.The temperature field has a great influence on the calculation of the thermal effect, the results of temperature stress were often different when calculate the thermal effect by using different forms of temperature gradient.Therefore, it was necessary to obtain the distribution law of temperature field by theories and experiments, which could apply in our borders or one region.Taking the Longtanhe Bridge as the engineering background, vertical and transverse fitting curves of box beam and box pier were obtained with the way of curve fit, temperature field and its influencing factors were analyzed.The software used in this thesis is the Finite Element Analyze Software MIDAS/Civil. By using 3-dimension beam element, the bridge was divided into 452 units in accordance with section properties. The analytical model of Longtanhe Bridge (right line) was built up. thermal effect was analyzed, respectively according to the temperature gradient model of chinese highway bridge design general specification code JTG D60-2004,the vertical temperature gradient model of box girder, the vertical and transverse temperature gradient model of box girder, and the temperature gradient model of the bridge considering the temperature gradient of box girder and box pier. obtained the distribution law of stress and displacement under different temperature gradient model, analyzed the displacement and stress of the box girder, which been influenced by the temperature field of box pier, compared and analyzed the conclusion of the calculation, Obtained some beneficial conclusions, which provide reference for the design of long span continuous rigid frame bridge with high pier.